Frequently Asked Questions About about Vaccines and Vaccination
FREQUENTLY ASKED QUESTIONS ABOUT VACCINES & VACCINATION AGAINS COVID-19
There is still no definitive answer to this question, as more time is needed to monitor the vaccinated in order for the analyses to be more accurate and the conclusions to be more definite. Data from studies published in The New England Journal of Medicine (NEJM) show that in all participants who received the Moderna vaccine during the phase I trial, protection remained high for at least six months after the second dose of the vaccine. The data for the Pfizer Biontech vaccine are similar. The Johnson & Johnson vaccine was introduced later, and researchers are still collecting data on the duration of protection after vaccination. Data on information-based RNA (mRNA) vaccines are promising – they show a gradual and slow decrease in serum levels of protective antibodies. The slow decline in antibodies predicts that protection against mRNA vaccines will be effective for at least a year. In addition to circulating antibodies, post-vaccination lymphocytes of cellular immunity (B- and T-lymphocytes) can respond quickly and control infection. Protective antibodies in humans are a key focus, in part because these proteins are easily measured by blood samples. Studies of T-lymphocytes in their ability to kill virus-infected cells in the context of COVID-19 have shown that T-lymphocytes can also provide important protection, although this is more difficult to measure.
No one knows for sure whether one vaccine will lead to a longer duration of immunity than other vaccines. Information RNA-based vaccines (from Pfizer and Moderna) that have shown a strong response (up to 95% efficacy in clinical trials) are thought to have the potential to elicit the longest-lasting immunity. Both vaccines use relatively new technology that delivers a small portion of the genetic code of the SARS CoV-2 virus to the body to provide instructions for making copies of the spike protein that will stimulate the immune response. Vaccines from the pharmaceutical companies Astra Zeneka and Johnson & Johnson use a different and more traditional approach, which includes an inactive adenovirus (a common virus that can cause respiratory infections and other diseases when active). The duration of immunity also depends to some extent on the patient – there may be variations in immune responses in different people, depending on factors such as age, concomitant diseases and medications they take. There is growing evidence that people who have been vaccinated against COVID-19 are less likely to become infected with SARS-CoV-2 and that if they become infected they are less likely to have symptoms of a serious illness. However, there is also evidence that existing vaccines may offer less protection against new variants of SARS-CoV-2, such as the delta variant. The Israeli Ministry of Health provided data that the effectiveness of the Pfizer-BioNTech vaccine in preventing symptomatic COVID-19 dropped to 64% in the 6 months following vaccination. An important fact, however, is that two doses of Pfizer are still able to prevent serious illness in 93% of cases. The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) said in a joint statement that they would recommend booster doses of vaccines if and when science proves necessary. Vaccine boosters are additional doses of vaccine that should provide additional protection against the infectious disease for which the vaccine is intended, as the effects of some vaccines may diminish over time. Boosters are common in well-known vaccines – for example, the flu vaccine, which requires a booster every year; the tetanus, diphtheria and pertussis vaccine (DTaP) – which requires a booster every 10 years. For some vaccines, getting lower doses is more often more effective than getting a single higher dose of vaccine. This approach allows the immune system to build its immune response sustainably. When the immune system remembers certain antigens that have previously activated it, it can react much faster the next time it encounters them. Although many vaccine boosters are identical to previous doses, some have been modified to improve their efficacy. For example, the flu vaccine is changed every year to respond more effectively to new mutations in the flu virus.
Analyses to date have shown that those with COVID-19 can maintain immunity to the virus for at least 8 months. Immune cells and antibodies that circulate in the body can recognize and kill the virus when it comes in contact with it again, preventing disease or reducing the severity of the disease. The components of the immune defense include: antibodies, which are proteins circulating in the blood that recognize viruses and neutralize them; T-lymphocytes, respectively helpers (T-helpers), which help to identify pathogens and T-killers (T-killers), which kill pathogens; B – lymphocytes that produce new antibodies when the body needs them. Investigations into cases of reinfection and the factors that lead to it are ongoing. Re-exposure monitoring of a significant number of people is required. According to a study published in the journal Science, immunity after COVID-19 can last more than 8 months. According to Dr. Shane Croti, a professor at the La Jolla Institute of Immunology in California who led the study, his team measured all four components of immune memory in nearly 200 people who were exposed to SARS-CoV-2 and restored. Their research also suggests that immunity can last much longer. In another study, published in The New England Journal of Medicine, researchers in Iceland followed 1,107 people who recovered from COVID-19 and gave positive serological tests for antibodies. For a period of 4 months, these antibodies against COVID-19 did not decrease. A study published in the journal Immunity found that people who recovered from even mild cases of COVID-19 produced antibodies for at least 5 to 7 months and could stay in the serum for much longer. Their team tested nearly 30,000 people in Arizona. Two recent studies show that immunity can last for at least a year. The first study, conducted by researchers at the Medical School in Washington, found that antibodies to the virus were detected at least 11 months after infection. A second study by researchers at Rockefeller University in New York found that people who recovered from COVID-19 could be protected up to 12 months later. The body’s immune response to COVID-19 is likely to last much longer, according to the researchers, but studies have continued for 11 to 12 months, respectively. Data from another study showed that people who were infected and then vaccinated developed very strong immune responses and had a much higher capacity to neutralize the virus, including the various variants of the virus. This means that those who have had COVID-19 should also be vaccinated. Vaccination will only increase the natural immunity that has already been developed, offering stronger protection
In general, an influenza vaccine is highly recommended, especially in at-risk patients. Vaccination against coronavirus infection does not change vaccination prophylaxis policies for other infectious diseases. Recommendations regarding the application schedule cannot be given. Co-administration has been described in a single study of the as yet unauthorized Novavax vaccine, with data showing that this administration protocol did not reduce the efficacy of the Covid-19 vaccine. On a theoretical basis, however, more pronounced local irritation and acute side effects can be expected with both vaccines. In this sense, although both vaccines are recommended, administration at intervals may be considered.
At this stage, regulatory agencies and expert councils do not make such recommendations. Manufacturers of some vaccines have submitted a tertiary “booster” dose for approval, but at this stage it is considered that the full vaccination campaign with one or two doses, depending on the type of vaccine provided, provides significant protection in terms of morbidity, risk of hospitalization. and death. A recently published study of data from the Health System in the UK shows that the full course of vaccines provides a significant protective effect, including and in the delta variant of SARS-CoV-2.
With regard to contraindications for vaccination in people with allergies, this only applies to patients allergic to some of the components of the vaccine or patients who have had an allergic reaction to the first dose of vaccine.
Patients with rheumatic and other autoimmune diseases should not have any concerns about vaccination against COVID-19. Studies available to date indicate that if a patient has rheumatic disease, it is preferable to be vaccinated against COVID-19 than to be infected with SARS-CoV-2. The specific question for patients with autoimmune diseases is not whether they should be vaccinated, but how to be vaccinated against their medicines in order for the vaccine to be most effective.
This may include stopping for a week or two a drug that the patient is taking for an autoimmune disease – it can be done without risking an adverse event or exacerbation of the disease, or vaccination just before the next dose of therapeutic treatment, so that the immunosuppressive aspect of therapy should be minimal.
COVID-19 infection is a very complex immune process in which there is growing evidence of the development of certain types of autoimmune problems, especially those associated with blood clotting and interference with normal cytokine production. SARS-CoV-2 has many ways in which it can alter the immune response and lead to autoimmune syndrome. How long this syndrome lasts, whether it is fixed or varies over time, and whether we will see the development of autoimmune diseases, is not yet fully understood.
Certain studies are certainly being done in this direction, as well as with regard to the ‘long’ COVID syndrome. It is not yet clear whether this complication is associated with a long-term viral infection or an autoimmune response. The vaccine, on the other hand, encodes only a portion of a single protein of the virus. It has adjuvants that stimulate the immune response. There is no evidence that the vaccine will cause autoimmune syndrome in the same way as the disease. So the vaccine is a far better option than the actual COVID-19 infection.
Data from another study show that 1 in 10 people with autoimmune diseases such as psoriasis, rheumatoid arthritis and inflammatory bowel disease may fail to develop an immune response after being vaccinated against COVID-19. Patients taking Methotrexate and Rituximab are the least responsive to the vaccine, but even if there is a reduced response due to autoimmune disease or taking these drugs, patients are still more likely to be protected against hospitalization and death than if not at all. receive the vaccine. In a study published on May 25, researchers analyzed the vaccine response in three groups of people from New York and Erlangen, Germany.
The researchers found that two groups responded well to the COVID-19 vaccine, with more than 90% showing a “strong” response: 208 healthy people and 37 people with immune disorders taking mostly “biological” drugs. However, only 62% of patients with autoimmune disease who took Methotrexate achieved an “adequate response”.
The explanation may lie in the overactivity of the immune system in patients with diseases such as rheumatoid arthritis. In another study published on May 11, U.S. researchers followed 89 patients at a rheumatology clinic who received at least one dose of COVID-19 vaccine. Of these, 21 patients did not develop antibodies, 20 of whom received Rituximab and one received Belimumab. However, another 10 patients taking Rituximab developed an antibody response.
Testing the immune response to vaccination is important for patients with autoimmune disease, as some of these patients may need a booster dose of the vaccine.
According to an interim analysis published in MedRxiv, approximately 84% of patients with autoimmune diseases developed an antibody response to the COVID-19 vaccine, compared with 98.1% of healthy healthcare professionals. The data show broad heterogeneity in response in immunocompromised patients. One in five participants in the lung transplant study developed an antibody response, and almost all patients with well-controlled HIV infection had a good antibody response.
From April 2021, a study began on the effect of vaccination against COVID-19 in immunocompromised patients (CoVICS). This ongoing, observational, prospective, cohort study included 107 healthy health workers from the University of Pittsburgh Medical Center and 489 immunocompromised adult patients who had completed their COVID-19 vaccination.
The researchers collected sera from all participants to measure the presence of IgG against the “spike” protein of SARS-CoV-2, based on a semi-quantitative analysis. The seropositivity rate was 37.2% in patients with solid organ transplantation, 83.8% in those with autoimmune disease, 54.7% in those with hematological malignancies, and 82.4% in those with solid tumors.
94.6% of patients with HIV infection have an antibody response. Among seropositive patients, antibody levels are much lower in those with a solid organ transplant. This study highlights the urgent need to optimize and individualize the prevention of COVID-19 in patients with immunocompromising conditions.
For patients with diabetes – COVID-19 is more severe and has a worse prognosis. A significant step in primary prevention is timely vaccination. Routine vaccination against pneumococcal pneumonia, influenza and hepatitis B is recommended in patients with diabetes mellitus who have good efficacy and a reasonable safety profile.
With clinical data supporting a strong neutralizing antibody response in patients with COVID-19, vaccination in individuals with diabetes mellitus should be a priority. There are still many unresolved issues regarding the preferred type of vaccine, the efficacy and durability of the vaccine, the frequency of administration, vaccination in children (<18 years) and pregnant / lactating women and should be investigated in more detail in future studies. Whether the patient has type 1 or type 2 diabetes, prediabetes or gestational diabetes, COVID-19 vaccines are safe.
There is no known interaction between vaccines and diabetes medicines, so it is important to continue taking medication or insulin. Some patients with diabetes have higher blood sugar levels for 1-7 days or more after the vaccine, so post-vaccination blood sugar monitoring is necessary. Children over the age of 12 can get the vaccine and it is recommended that they do so – especially if they have diabetes.
For patients with chronic lung disease, the benefits of vaccination far outweigh any potential risks. The vaccine protects not only against infection with COVID-19, but also against the complications of respiratory failure and death, and they are becoming much more important for patients with chronic obstructive pulmonary disease (COPD).
Patients with COPD, including emphysema and chronic bronchitis, are considered at higher risk of developing severe disease than COVID-19, according to the Centers for Disease Control and Prevention (CDC). Also people with other chronic lung diseases, such as moderate to severe asthma, cystic fibrosis, pulmonary hypertension and interstitial lung disease, or other conditions involving lung damage.
Patients with COPD, including emphysema and chronic bronchitis, are considered at higher risk of developing severe disease than COVID-19, according to the Centers for Disease Control and Prevention (CDC). Also people with other chronic lung diseases, such as moderate to severe asthma, cystic fibrosis, pulmonary hypertension and interstitial lung disease, or other conditions involving lung damage.
Patients with COPD are not at higher risk of becoming infected with COVID-19. Unfortunately, the same study found a link between COPD and a higher risk of death in people hospitalized with COVID-19. Discontinuation of medication before vaccination, even oral or inhaled corticosteroids, is not recommended, although this may potentially reduce the effectiveness of the vaccine.
Most SARS-CoV-2 vaccines should be given in two doses, but data from some studies already support the idea that mixing the Oxford-AstraZeneca vaccine with the Pfizer-BioNTech vaccine elicits an immune response similar to or even stronger. from one that develops after two doses of either vaccine.
The results, announced a week ago by a British research group, show that the combination sometimes exceeds two doses of the same vaccine, and similar data have been reported by German researchers.
The results reassure researchers that combining other vaccines against COVID-19 that have not yet been tested together may also be effective. At least 16 vaccines have been approved for use in one or more countries, and studies on blending vaccines have so far been few, so more extensive studies and long-term monitoring of side effects are needed.
Vaccine mixing studies have been largely driven by safety concerns about a vaccine developed by Oxford University and the pharmaceutical company AstraZeneca. There have been reports of rare cases of thrombosis with thrombocytopenia, as a result of which in March 2021, some European countries decided to discontinue the use of this vaccine in certain groups of people.
This left many people partially vaccinated, so they had to switch to another type of vaccine for their second dose. In May 2021, researchers from the Carlos III Health Institute in Madrid announced the results of the CombiVacS study. The study found a strong immune response in people who received a second dose of Pfizer BioNTech vaccine, 8-12 weeks after receiving one dose of the Oxford vaccine – AstraZeneca.
There was no direct comparison with people who received two doses of the same vaccine, but the authors found that in laboratory tests, those who received the combination produced 37 times more SARS-CoV-2 neutralizing antibodies and 4 times more SARS -CoV-2-specific immune T cells than people who had only one dose of the Oxford vaccine – AstraZeneca. By the end of June, more results appeared showing a similar effect. Sander and colleagues presented data from a study involving 340 health workers who received either two doses of the Pfizer-BioNTech vaccine or one dose of the Oxford-AstraZeneca vaccine, followed by a dose of Pfizer-BioNTech.
Both regimens elicit an immune response that includes neutralizing antibodies and T cells. A third study by researchers at the University of Saarland in Homburg, Germany, found that the mixed regimen elicited a better immune response than two doses of the Oxford vaccine, AstraZeneca. It is also similar or better than two doses of Pfizer vaccine – BioNTech. Combinations that provoke a good T-cell response may be better for people who have had an organ transplant and are taking drugs to suppress the immune system.
Safety issues remain. In the Com-COV study, mixing vaccines caused more side effects than administering two doses of the same vaccine, according to preliminary data published in May 2021. However, this was not the case in the Charité and Saarland or CombiVacS studies, where side effects did not occur. are more severe than with two doses of the same vaccine. This is probably due to the interval between doses.
Participants in the Com-COV study received their second dose four weeks after the initial dose, while participants in the German studies had at least nine weeks between the two doses. Some participants in Com-COV received doses at longer intervals; their data are expected by the end of July. The long-term possibility of rare side effects is one of the reasons why some researchers recommend that people currently adhere to the standard two doses of one vaccine. The vaccine mix can be used for vaccine supply problems.
The Com-COV study has already begun testing other vaccines in people who have received an initial dose of Oxford – AstraZeneca or Pfizer-BioNTech. One combination includes a protein vaccine developed by the pharmaceutical company Novavax. The other uses Moderna’s mRNA vaccine. A study is being conducted in the Philippines combining the inactivated CoronaVac virus vaccine, developed by Sinovac in Beijing, with the six other vaccines approved in the country and running until November 2022.
There is no consensus on this issue. COVID-19 infection helps the body build naturally defined protective antibodies. However, it may be advisable to take the second dose of the vaccine after recovery. In such a scenario, patients may need to reconsider their dosing schedule, but the completion of the vaccination course may be discussed with the treating physician. What is certain is that it is completely pointless to do serological tests for antibody titers before vaccination, between doses, or afterwards, except in the range of acute academic curiosity.
People may be offered vaccination, regardless of their history of symptomatic or asymptomatic SARS-CoV-2 infection; this includes people with prolonged symptoms after COVID-19. Data from clinical trials indicate that currently permitted vaccines against COVID-19 can be safely administered to people with a proven history of SARS-CoV-2 infection. Serological tests to assess the immune status of a previous infection are not recommended.
Vaccination of people with a known current SARS-CoV-2 infection should be delayed until the person has recovered from the acute illness (if the person has had symptoms) and they have met the criteria for termination of quarantine. This recommendation applies to people who have been infected with SARS-CoV-2 before receiving any vaccine dose, as well as to those who have been infected with SARS-CoV-2 infection after the first dose of mRNA vaccine, but before receiving the second dose.
Although there is no recommended minimum interval between infection and vaccination, current data suggest that the risk of reinfection of SARS-CoV-2 is low in the months after initial infection, but may increase over time.
Absolutely not. In large-scale studies of Moderna and Pfizer vaccines, the number of successful births in the vaccinated groups did not differ statistically from that in the placebo-treated group. A study from an assisted reproduction clinic in Israel shows that vaccination does not alter ovarian function, the synthesis of female sex hormones and ovum.
Based on the mechanisms by which these vaccines work in the body, experts believe that they are unlikely to pose a risk to pregnant women. However, there are currently limited data on the safety of COVID-19 vaccines in pregnant women. Clinical trials are currently being conducted and planned to investigate the safety of COVID-19 vaccines and the benefit-risk balance in pregnant women. Vaccine manufacturers also collect and review case data from completed clinical trials in which patients have been vaccinated and become pregnant. Studies in animals treated with Moderna, Pfizer-BioNTech or J & J / Janssen vaccines before or during pregnancy do not give rise to safety concerns during pregnancy. Regulatory agencies have safety monitoring systems in place to collect information on COVID-19 vaccination during pregnancy and will closely monitor this information. The early data of these systems are encouraging. These data do not identify any safety concerns for pregnant women who have been vaccinated or for their babies. However, more data is needed to formulate a credible recommendation.
The vaccine, developed by the Gamalea Institute, is not approved for use in the EU. It is important to note that according to facts provided by Reuters, in their communications with the European Medicines Agency, the manufacturers of the Russian vaccine Sputnik V have repeatedly failed to provide data that regulators consider to be standard required in the drug approval process. The review of the safety and efficacy data of the European Medicines Agency (EMA) has been postponed as the deadline for submitting data on clinical trials of the vaccine has been missed. At the beginning of June, the EMA had received almost no production data and the clinical data provided were incomplete. Separately, an evaluation of Sputnik V by a French delegation of scientists before the EMA review found that producers were unable to document that biotechnology production complied with the specific EU regulation on disease prevention. The EMA launched its official review of the Russian vaccine in March, and before that delay was expected to decide in May or June whether to approve the use of the drug in the EU.
A particular problem for the EMA is the lack of any evidence of adverse reactions. It is standard practice in the EU for manufacturers and developers to submit such forms. On this basis, the review of efficacy and safety data by the European regulator is unlikely to be completed by the end of the summer. The MAH had similar problems with the regulatory agencies in Slovakia and Brazil. The vaccine is currently being monitored by the WHO. Post-marketing data from Argentina, the UAE, Russia and San Marino are encouraging, but given the European market for four highly effective and safe vaccines, postponing vaccination pending the Russian vaccine is, to put it mildly, unreasonable.
The detection of antibodies and, accordingly, the determination of their titer depends on the sensitivity of the applied test. Tests determining antibodies can be divided into two groups: (1) fast (10-15 min) quality immunochromatographic tests and (2) slower (several hours) semi-quantitative enzyme-linked (ELISA) and chemiluminescent (CLIA) serological tests. Tests in both groups detect IgM, IgG or both, and some detect IgA. However, not all antibodies have activity that neutralizes the infectious properties of the virus. The neutralizing activity of antibodies is determined by a virus-neutralizing reaction, which in the case of SARS-CoV-2 is performed in specialized laboratories operating in the 3rd level of biosafety. Recently, surrogate virus-neutralizing tests have been developed that allow work in the lower 2nd level of biosafety.
It should always be borne in mind that the reactivity and binding activity of antibodies do not correlate with their neutralizing activity and their neutralizing activity is not equal to immunity. Also, the humoral immune response is not the only level of protection in SARS-CoV-2 infection.
At present, the scientific community is united around the following opinion: the minimum level of anti-SARS-CoV-2 antibodies providing protection against infection is unknown, and it is not known what proportion of the detected antibodies have virus-neutralizing activity.
There is currently no recommendation to determine an antibody titer before starting post-mortem vaccination, nor a requirement for a minimum titer to effect immunization. Currently, the scientific community is united around the following recommendation: after illness, the first dose of the vaccine should be given within 3 to 6 months after complete recovery from COVID-19. According to experts, this application of the vaccine plays the role of a booster dose, because the infection itself played the role of the first dose.
There is currently no consensus or recommendation for a minimum protective antibody titer after vaccination. Not all antibodies identified with commercially available kits have neutralizing activity. Moreover, it should always be borne in mind that the reactivity and binding activity of antibodies do not correlate with their neutralizing activity and their neutralizing activity is not equal to immunity. Also, the humoral immune response elicited by antibodies is not the only level of protection against SARS-CoV-2 infection. At present, it is not recommended to draw conclusions about the degree of protective post-vaccination immunity depending on the amount of antibodies determined by commercial kits.
Cellular immunity contributes to the rapid clearance of the virus (viral clearance) upon re-infection, but the longevity and differentiation of SARS-CoV-2-specific memory cells remain unclear. Data from a study analyzing SARS-CoV-2 CD4 + and CD8 + T-cell responses in patients with a convalescent (recovery) period of COVID-19 up to 317 days after the onset of symptoms found that memory T-cell responses maintained during the study period, regardless of the severity of COVID-19. Assays show persistent polyfunctionality and ability to proliferate T-cells specific for SARS-CoV-2. Among SARS-CoV-2, CD4 +, and CD8 + T-specific cells, the proportion of memory stem cell-like T cells (TSCM) increases, reaching a maximum of approximately 120 days after the onset of disease symptoms. Data from this study indicate that SARS-CoV-2-specific T cells are long-lasting after recovery from COVID-19, thus supporting the feasibility of effective vaccination programs as a measure of COVID-19 control.
In 2020, data from a study published in Nature showed that people with severe acute respiratory syndrome (SARS) (caused by coronavirus in 2003) maintained T-cell immunity for 17 years after recovering from the disease.
No. There is no such data.
All drugs have side effects. After new vaccines, many people experience local irritation and redness, sometimes soreness at the site, and less often general malaise and fever. These effects disappear very quickly and it is rare to miss more than one working day. Severe side effects are extremely rare and life-threatening events occur at a frequency of several cases per million doses administered. The risk of autoimmune thrombocytopenia with an increased risk of thrombosis in one of the vector vaccines is about and below 1: 100,000, and in the other significantly lower. The risk with the Russian vector vaccine is unknown because no post-authorization safety data have been provided. By comparison, widely used nonsteroidal anti-inflammatory drugs, some of which are available over-the-counter, are associated with about 2,000 deaths a year in the United Kingdom and more than 16,000 a year in the United States.
When making a motivated decision for or against vaccination, we should pay attention to the disease itself. The risk of complications and hospitalizations with Kovid-19 is over 10%, and in our country the mortality is about 4% (4: 100).
Vaccines approved for use in the EU have an excellent safety profile. Conversely, the risk of complications, hospitalization and death against the background of concomitant diseases is significant, and it should be recalled that the mortality rate in our country is about 4%. The risk of severe, life-threatening side effects with vaccines is very low.
Unfortunately, there are still medical professionals who are not convinced of the efficacy and safety of vaccines, which is why they give conflicting messages to their patients. This leads to mistrust of vaccines and a lack of awareness of their importance in controlling the epidemic. To be approved, vaccines must undergo a careful multi-phase test process for safety and efficacy analysis. Clinical trials of COVID-19 vaccines have done just that, involving thousands of participants. Vaccines were produced so quickly, not because the process was hasty and incomplete, but because scientists had significant previous experience with other coronaviruses, such as the causative agents of SARS (severe acute respiratory syndrome) and MERS (Middle Eastern respiratory syndrome). Clinical trials of the vaccines have shown high efficacy against COVID-19, but similar data are available from a large real-life study.
This study confirms that Pfizer-BioNTech and Moderna vaccines are more than 95% effective in preventing infection. The study, published in the Annals of Internal Medicine, included 54,360 people who were tested for SARS-CoV-2 infection in the U.S. Department of Veterans’ Health System and 54,360 participants in the control group. The overall effectiveness of the vaccines 7 or more days after the second dose was 97.1% (95% CI, 96.6% – 97.5%). The efficacy was 96.2% (CI, 95.5% – 96.9%) for the Pfizer-BioNTech vaccine and 98.2% (CI, 97.5% – 98.6%) for the Moderna vaccine. The effectiveness remains over 95%, regardless of age group, gender, race or comorbidities. The average age is 61 years, 83.6% are men and 62% are white. This is a large-scale study done in an older male population with an increased risk of serious illness. And the results fully confirm what clinical trials have shown us, that these are extremely effective vaccines. The group studied has significant comorbidities, including diabetes, heart and lung disease. And these results are confirmed by analyzes of the subgroups. At the same time, COVID 19 infection is associated with a high risk of complications in patients. A study of patients hospitalized in the UK with SARS-CoV-2 infection showed that approximately half of the patients developed at least one complication. The degree of complications is high among all age groups with and without pre-existing comorbidities. Renal, pulmonary and systemic complications are the most common.
Neurological, gastrointestinal, liver and cardiovascular complications have also been described. About 27% of those recovered have a reduced ability to take care of themselves after hospitalization, which can affect long-term health care. Complications associated with damage to blood vessels, kidneys, eyes, brain, skin, heart, and gastrointestinal tract can result from severe SARS-CoV-2 infection. Current data, focused on COVID-19 mortality in the United Kingdom, show that 26% of patients admitted to hospital with COVID-19 die from the disease. Of the patients included in the final analysis, the study reported that about 32% died during the study and approximately 44% of survivors had at least one complication. The incidence of at least one complication varies from 27% in patients aged 19–29 years without comorbidities to 58% in patients aged 60–69 years with two or more comorbidities. The incidence of complications increases with age and is higher in patients with pre-existing comorbidities and in men. Patients with complications had a 2.4-fold higher risk of poorer self-care after discharge, with neurological complications most strongly associated with the worst functional outcomes. About 27% of survivors with a complication had a reduced ability to take care of themselves.
The long-term effects of COVID-19 are still unknown. Healthcare professionals are investigating long-term complications of SARS-CoV-2 infections, including symptoms that persist for months after the person’s initial infection with the virus. A recent study published in the journal PLOS OneTrusted Source reported that a quarter of study participants had long-term symptoms of COVID-19 between 6 and 8 months after the initial infection. Some of the common long-term symptoms of SARS-CoV-2 infection include dyspnea, fatigue, cough, cognitive impairment and pain. The long-term symptoms of COVID-19 and how SARS-CoV-2 causes these symptoms are areas that are still being studied.
The qualitative and quantitative composition of the vaccines, as well as the full list of excipients, are described in the Summary of Product Characteristics, respectively 2 and 6.1. from them.
Hypersensitivity to the active substance or to any of the excipients is an absolute contraindication to the use of the products. Other allergic conditions are not contraindicated for immunizations. People who are currently at an exacerbation of their allergic disease should postpone their immunization. The recommendations of the Clinical Allergology Expert Council regarding the vaccination against COVID-19 are publicly available.
The US Food and Drug Administration likes to say, “In God we trust, the others should provide data.” Our beliefs have little to do with successfully dealing with this crisis.
Vaccines for Covid-19 have been studied in a large population in controlled clinical trials, covering more than 100,000 people for all registered vaccines. More importantly, more than a billion doses have already been given worldwide, making some of the vaccines one of the most widely used drugs ever. The data from the actual use are infinitely convincing – the comparison of the frequency of symptomatic disease, hospitalization and death in vaccinated versus unvaccinated shows an efficiency that in some of the products is close to 90%.
The data from the Israeli Ministry of Health are indicative. During the follow-up period described in this publication (January 24 to April 3, 2021), 232,268 SARS-CoV-2 infections were identified, 7,694 COVID-19 hospitalizations, of which 4,481 were in severe or critical condition, and 1113 deaths from COVID-19 in persons over 16 years of age. As of April 3, 2021, 4,714,932 (72 · 1%) of the country’s population over the age of 16 (6,538,911 people) had been fully vaccinated with two doses of the Pfizer BNT162b2 vaccine. Data on morbidity, hospitalization and mortality in vaccinated versus unvaccinated showed that the efficacy of the vaccine 7 or more days after the second dose was 95.3% against SARS-CoV-2 infection, 91.5% against asymptomatic SARS-CoV-2 infection , 97.0% versus symptomatic COVID-19, 97.2% versus hospitalization associated with COVID-19; 97.5% against hospitalization with severe or critical COVID-19 and 96.7% against death associated with COVID-19.
Recently published data from the United Kingdom show that although at one dose the efficacy against the delta variant of SARS-CoV-2 is reduced at the end of the vaccination course, the protective effect is comparable to that against the alpha variant of coronavirus. In the BNT162b2 vaccine, the two-dose efficacy was 93.7% for infection with the alpha variant of the virus and 88.0% for the delta variant. With the ChAdOx1 nCoV-19 vaccine, the efficacy of both doses was 74.5% in the alpha variant and 67.0% in the highly contagious delta variant.
It takes time to build immunity and respectively an effective immune response. The protective response does not begin to appear until about 2 weeks after the first dose of two-dose vaccines, after which it continues to increase over time. After a few weeks, however (the length of this period is still being studied), the protective response begins to fade. Therefore, a second, “booster” dose is given, which consolidates the immune response over a much longer period.
The enhancing effect of the second booster application also appears after about 1-2 weeks. In short, after the first application of the vaccine, it takes time to build immunity. During this period, if the virus circulates in the population, the vaccinated person is at risk of infection and disease. Moreover, the human population is heterogeneous. As there are variations between different individuals, so there are variations in the immune response to infection or vaccination. There are healthy individuals who simply do not build a tense immune response. According to various studies, the relative share of these individuals is between 1 and 10% of the population. Moreover, with age, the quality of the immune response weakens.
There are also medications whose long-term use as maintenance therapy also weakens the immune response. At the first encounter with the antigen (as a result of the first application of the vaccine), only about 50% of those vaccinated develop a sufficiently good immunity that is able to prevent disease. After the second application, however, this percentage increases significantly and reaches values of 80-90%. Both post-infectious and post-vaccine immunity provide different levels of protection – protection against death, protection against hospitalization due to severe disease, protection against disease, protection against infection. A distinction must be made between infection and disease. A positive PCR result for SARS-CoV-2 means infection with the virus, but not yet disease. As a result of the infection, only some individuals will develop symptoms of COVID-19 disease. Vaccines are very good, but not perfect. No vaccine works 100% for everyone. Although rare, infection or illness after vaccination is possible, but even less likely to be seriously ill and hospitalized. The disease is much more likely to be mild after vaccination.
Cases of illness after completion of an immunization course are referred to as “breakthrough cases”. The occurrence of breakthroughs depends on three main factors:
- From the virus – the pandemic virus SARS-CoV-2, continuing to circulate among the human population, mutates to variants of public health (alpha, beta, gamma, delta, etc.), which are both more infectious and more better adapted to avoid the host’s immune response.
- From the administered vaccine – in order to fully manifest the protective effect of vaccines, it takes time to develop a protective immune response. This usually happens about 2 weeks after completing the vaccination course.
- From the individual immune response – in the human population there are healthy individuals who do not build enough intense immunity after vaccination. There are also clinically healthy individuals who, due to concomitant disease or genetic predisposition, do not build a quality immune response. Moreover, with age, the quality of the immune response also weakens. Prolonged use of certain medications as maintenance therapy for certain diseases may also weaken the development of a full immune response. And even in individuals who have developed a good enough and intense immune response, there is a possibility of fading post-vaccination immunity.
Recent data from studies show that vaccinated people are likely to develop a better immune response, especially with new variants of the virus. Data from these studies indicate that the neutralizing antibodies generated in response to the mRNA vaccine target a wider range of SARS-CoV-2 variants that carry one-letter changes in the key portion of the spike protein compared to with antibodies derived from infection.
These latest analyzes are reported by Jesse Bloom, Alison Green and their team at the Fred Hutchinson Cancer Research Center in Seattle. In an earlier study, this same team focused on the receptor-binding domain (RBD), a key region of the spike protein that binds SARS-CoV-2. This RBD is especially important because the virus uses this part of its protein to attach to another protein called ACE2 on human cells. This makes RBD a major target for both naturally occurring antibodies and those generated by vaccines. The group’s previous study in Seattle outlined any possible mutations in RBD that would alter the virus’s ability to bind ACE2 and / or RBD-targeted antibodies to block the virus. In their new study, published in the journal Science Translational Medicine – Bloom, Greaney and colleagues revisited the thousands of possible variants of RBD to understand how antibodies can block this domain.
All vaccinated individuals included in the study received two doses of Moderna’s mRNA vaccine. Through careful study of the results, the researchers found important differences between acquired immunity in people who have been vaccinated and unvaccinated people who have previously been infected with SARS-CoV-2. In particular, antibodies derived from the mRNA vaccine are more focused on RBD than antibodies caused by infection, which are more often directed to other parts of the spike protein. Importantly, vaccine-induced antibodies target a wider range of sites in RBD than those caused by natural infection. These findings suggest that innate immunity and vaccine-generated immunity to SARS-CoV-2 will differ in the way they recognize new viral variants. Moreover, antibodies acquired with the vaccine may be more likely to successfully block new variants of SARS-CoV-2, even when the variants carry new mutations in RBD. It is not entirely clear why these differences exist in the reactions caused by vaccines and infections. In both cases, RBD-targeted antibodies are derived from the recognition and response of the immune system to the viral spike protein.
The Seattle team suggests that these differences may occur because the vaccine presents the viral protein in slightly different configurations. It is also possible that the administration of the mRNA vaccine may alter the way antigens are presented to the immune system, leading to differences in the antibodies produced. A third difference is that the natural infection only exposes the body to the virus in the airways (unless the disease is very severe), while the vaccine is given intramuscularly, where the immune system may have an even better chance of responding vigorously. Evidence continues to show that acquired immunity from vaccines still offers significant protection against new options that are now circulating around the world. It is hoped that the immunity acquired through vaccines will indeed provide long-term protection against SARS-CoV-2 and end the pandemic.