Pfizer Inc. and BioNTech SE and another from Moderna Inc., have experienced fever, headache and pain at the site of the injection.
These side effects generally disappear quickly. As many as 10 people have had a serious allergic reaction, called anaphylaxis, to the vaccines.Also Read | The march of 2020 in 10 key long reads1.
What is anaphylaxis?The body fights foreign invaders through a variety of mechanisms that include making protective proteins called antibodies, releasing toxins that kill microbes, and marshaling guardian cells to battle the infection.
As in any conflict, sometimes the effort to repel an infection can itself be damaging. In rare cases, it can produce runaway inflammation and swelling of tissues in a serious allergic.