The Pfizer / BioHTech vaccine: benefits and risks

The US Food and Drug Administration (FDA) is about to give a “green light” for use in the US for the first vaccine against Covid-19, developed by Pfizer and its German partner BioNTech. A preliminary report from the institution claims that the vaccine “meets the prescribed criteria” for success during clinical trials.

It provides, for the first time, public information on the known and unknown benefits and risks of the vaccine, identified in a clinical trial between July 27 and November 14 of this year. (see below, p.). It started with nearly 44,000 participants, about half vaccinated and the other half receiving placebo.

A group of outside experts will consider the report from the Food and Drug Administration (FDA) on Thursday, December 10. On Tuesday, the agency also released a second report, from vaccine maker Pfizer and its German partner BioNTech.

In 95% of cases, the vaccine, after dose 2, reduced the risk of Covid-19.

The FDA briefing document describes the main benefits of the vaccine, namely the reduction of the risk of Covid-19 and the severe course of the disease. It is recommended that the vaccine be given in two doses at 21-day intervals to ensure long-lasting immunity. The average efficacy of the vaccine is 95%, which is achieved after the seventh day of dose 2. Between dose 1 and dose 2, the efficacy is 52.4%.

Initial criticism of the vaccine was that it would affect only mild to moderate disease, but now it appears to reduce the risk of a severe course.

Dr. Anna Durbin, a vaccine researcher at Johns Hopkins University, told the Wall Street Journal that it was promising that the vaccine would provide protection as early as day 10 after the first dose.

The most common side effects of the injection are a reaction at the injection site, tiredness, headache, muscle aches, chills, joint pain, and fever.

Serious side effects are very rare, usually occurring after the second dose, and paradoxically less common in adults over 55 and slightly more common in younger people, according to the agency report. However, it has not been shown that they are directly related to the vaccine, since in most cases they are in the same proportion as in the general population.

Data are limited to assess the effect of the vaccine against transmission of (Covid-19) by people who are infected despite vaccination, according to the report.

6 deaths, but no evidence of association with the vaccine

Six people died during the vaccine trial. Two of them are from the vaccinated group and four from the placebo group. None of the deaths were assessed by the researchers as vaccine-related, according to the document.

In the group of people who died from the vaccine, one person had atherosclerosis and obesity. He died three days after the first dose of the drug, and the other participant suffered a heart attack 60 days after the second dose, registering his death three days later.

In the placebo group, two people died of stroke and heart attack, and the cause of death for two more participants has not been established.

Half of the dead in both groups are over 55 years old.

Among the disputes during Thursday’s meeting of the group of experts is expected to be the demographic profile of the people included in the clinical trial, as it turns out that 80% of them are white.

Vaccine efficacy by population groups. Pfizer data

THE BENEFITS AND RISKS IN BRIEF *

1. The known benefits of the vaccine

Reduction of the risk of Covid-19 infection at least 7 days after the second dose;

Reduce the risk of Covid-19 infection between the first and second doses;

Reduce the risk of severe Covid-19 anytime after the first dose.

These data on the effectiveness of the vaccine are confirmed among different racial and ethnic groups, among people over 65 years of age, and among people with any of the following conditions: obesity, diabetes, hypertension, and chronic heart and lung disease.

2. The unknown about the vaccine

The efficacy of the vaccine after 2 months of dosing 2 is unknown, since the clinical trial has so far lasted 2 months;

It is not clear how effective the vaccine is among certain groups at increased risk for severe Covid-19, such as people with compromised immunity (HIV carriers, for example);

It is not clear how effective the vaccine is in people who have had Covid-19, as not enough people have been studied in this group. There is limited evidence that the vaccine is more beneficial for this group due to the risk of reinfection;

Efficacy in children is unknown: very few children under 16 have been tested to see if the vaccine is effective for them;

It is not clear how the efficacy of the vaccine will be affected in the future due to possible changes in the nature of the pandemic and in the virus itself;

The efficacy of the vaccine in asymptomatic infection is also unknown; the data are too limited to conclude whether the antibodies are an immune response elicited by the vaccine or a reaction to the infection itself.

The efficacy of the vaccine against the long-term effects of Covid-19 affecting certain organs is unknown;

The effectiveness of the vaccine in reducing mortality is unknown; To study this indicator, it is necessary to test the effect of the vaccine in a much larger number of people at high risk of Covid-19. However, other vaccines (such as the flu) that are effective against the disease also prevent disease-related mortality.

The effectiveness of the vaccine against the spread of the coronavirus is unclear; there are insufficient data to establish effectiveness against the spread of the virus in people who are infected despite vaccination. However, the established high efficacy against people with Covid-19 symptoms can lead to the prevention of general spread among a population with a sufficiently high range of vaccinated.

3. Known risks

The vaccine can cause a reaction, which usually lasts several days.

The best known side effects are: reaction at the site of infection (84.1%), fatigue (62.9%), headache (55.1%), muscle pain (38.3%), tingling ( 31.9%), joint pain (23.6%). , temperature (14.2%).

Adverse reactions are usually mild to moderate.

Among the people who reported any reaction, there were more people vaccinated than those who had been injected with placebo (137 people – 0.63% of those vaccinated vs. 111 people – 0.51% of those taking placebo).

Serious adverse reactions were documented in 0.0 – 4.6% of the participants. They were more common after dosing 2 in people younger than 55 years (4.6%) than in those older than 55 years (less than 2.8%).

There is evidence that the vaccine may be associated with some cases of lymphadenopathy (swollen lymph nodes), which also occurs with other vaccines, as well as the common cold.

Very rare cases of serious adverse events (less than 1%) have been documented, but are equally frequent in both the vaccinated group and the general population. These include shoulder injury (1 case), ventricular arrhythmia (1 case per patient with heart disease), and lymphadenopathy.

4. Unknown dangers / lack of data

The safety of the vaccine in children under 16 years of age, pregnant women, nursing mothers, and immunosuppressed individuals is unknown.

Cases of adverse reactions are very rare or require a longer period to register.

In particular, more cases of appendicitis were reported in the vaccinated group than in the placebo group, but their number corresponded to the proportion in the general population and a causal relationship between the vaccine and cases of appendicitis has not been found.

The same was true of the 4 reported cases of so-called Bell’s palsy (paralysis or muscle weakness of the middle of the face) compared to 0 cases in the placebo group. However, these 4 cases do not have a frequency higher than the standard in the population according to age groups.

The data obtained does not show a risk of complications of the disease due to the vaccine, on the contrary, they speak of effectiveness against a severe course of Covid-19. However, the risk in question must continue to be monitored in the future and remain unknown for longer periods of time.

* Information is presented as announced in the Pfizer / BioNTech Vaccine Information Document to the US Food and Drug Administration.