How long after the second Pfizer vaccine is it effective?

Stock image. Karolina Grabowska
Stock image. Karolina Grabowska (Pexels)

As distribution and administered shots continue, here are some key questions and answers surrounding the Pfizer vaccine.


How long until a second dose is proven effective?

A study in the New England Journal of Medicine found that after a second dose of the Pfizer vaccine, efficiency rose to 95% after seven or more days.

Are side effects more intense after a second shot?

Possibly, but that isn’t necessarily a bad thing, according to the Centers for Disease Control and Prevention. That means the body is building protection, and those side effects should go away in days.

What are some common side effects?

In the arm where you get the shot, common side effects can be pain, redness and swelling, according to the CDC. In the rest of the body, it can be fatigue, headache, muscle pain, chills, fever and nausea.


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