Israelis Getting Their Second Vaccine Shot Experience More Side Effects. Here's Why

Experts explain that the side effects Israelis are experiencing after their second dose of Pfizer's coronavirus vaccine – such as fatigue, headaches and muscle aches – are our immune system at work

Ido Efrati
Ido Efrati
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Ido Efrati
Ido Efrati

As Israelis begin receiving their second dose of Pfizer's coronavirus vaccine, they have been reporting more frequent, and sometimes more severe, side effects compared to the first dose.

According to Pfizer’s findings in clinical trials, the second “booster” dose causes physiological reactions more frequently. This is not unexpected: it is the second stage of developing an immune defense against the virus, which is intended to further hone and focuse the immune system and deepen its “memory” of the virus.