A new study - safety of the Pfizer Covid-19 vaccine in a nationwide setting

A new study – safety of the Pfizer Covid-19 vaccine in a nationwide setting

A recent (August 2021) article from the most powerful clinical medical journal, the NEJM, PMID 34432976.

This article aimed to assess the safety of the Pfizer mRNA vaccine in a very big population study in people aged more than 16 years. Moreover, they also assessed the incidence of the same potential vaccine adverse events in people who were infected with Covid-19.

Important, isn’t it?

Methods – data was taken from the largest health care organization in Israel. For every potential adverse reaction, a matched vaccinated persons to unvaccinated persons was done according to sociodemographic and clinical variables for a period of 21 days after each vaccine dose. Also, the authors did the same comparison between people who got infected with COVID-19 to uninfected people.

Results – vaccinated vs non-vaccinated people – almost 900 thousand people in each group (!), myocarditis was found more often in the vaccinated group of people (risk ratio of 3.2), lymphadenopathy (2.4), appendicitis (1.4) and herpes zoster infection (1.4).

Infected vs non-infected – almost 180 thousand people in each group, myocarditis in the infected group in a risk factor of 18.3. They also found many more complications in those who got infected.

Unfortunately, an age divided adverse event was not given for these two comparison.

Discussion – I am not sure this article main impact was to show us that the vaccine is safe, but it is to show us that it is better to get vaccinated than to get infected (or as the authors state “place these risk in context”). The risk of many adverse events is much higher in infected persons than in those wo got vaccinated.

Off Couse this is a very powerful study which supports the importance of the Covid-19 vaccine.

My only remark is that while there is no argue of the safety and importance of the vaccine, I wanted more from this study. I wanted the same comparison for specific age group.

We know, that previously healthy young males aged up to 30 years tend to have myocarditis after the vaccine. And we know that the same population in not in the risk group of severe disease when infected. So, I believe, the same results should have been given for each age group. I am not sure that the risk of having myocarditis in infected previously healthy young males is higher than the after the second dose of the vaccine…

Nevertheless, this important study put rare adverse event following vaccine in the context of getting infected and prove again, that avoiding Covid-19 by vaccination is a good decision.

Hope you got the message.

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