Most people who have been vaccinated against Covid-19 experience some side effects, but most are mild or very mild, according to a study published Wednesday in the medical journal JAMA Open Network. Serious side effects are very rare.
After a second dose of Pfizer/BioNTech or Moderna vaccine or one dose of Johnson & Johnson vaccine, about 80% of people reported some side effects – the most common being fatigue, muscle aches, pain headache and chills. But only 0.2% of people reported having an allergic reaction or anaphylaxis after being fully vaccinated – a total of 27 out of more than 11,000 responses.
For this study, researchers from the University of California, San Francisco, conducted daily, weekly, and monthly surveys of Covid-19-related health and events in a pure group of people. online session of adults from March 26 to May 19, 2021. The survey included nearly 20,000 participants, although not all participants answered all questions.
The study also found that there was a “strong association” with adverse reactions to the Covid-19 vaccine among people who reported being infected with Covid-19 prior to being vaccinated.
People who received the Moderna vaccine were twice as likely to have side effects as those who received the Pfizer/BioNTech vaccine, as were women. People who get the J&J vaccine have lower rates of side effects, along with older adults and people with asthma.
More about research: The researchers noted that although the surveyed group was diverse, rural residents and those with subjectively lower social status were underrepresented. Also, not all participants responded to all surveys, which could affect the results.