As anyone who has received a COVID vaccine provided by Pfizer or Moderna can attest, flu-like symptoms that can occur after the injection usually appear after the second dose. Most of the time, the only symptoms that people experience after their first injection are limited to a small swelling and pain at the point of injection.
At first glance, it is a little curious why the first dose of the vaccine produces minor symptoms, while the second dose can sometimes leave people completely passed out for an entire 24 hours. In fact, a volunteer who participated in the Pfizer clinical trial compared the side effects of the second dose to a “strong hangover” that caused headache, fever, chills and severe fatigue.
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There is, of course, a perfectly convincing and scientific explanation of why people tend to react more strongly to the second dose than to the first.
As Dr. William B. Greenough III of Johns Hopkins explains, the first dose of the vaccine begins to accelerate the body’s immune system. And seeing how Pfizer and Moderna’s COVID vaccines are built around messenger RNA (mRNA) technology, the first dose essentially tells the body how to prepare for and defend against the coronavirus.
That being the case, Greenough notes that by the time the second dose is administered, the immune system is already prepared to react and reveal “the big guns”.
Stanford professor Dr. Grace Lee adds:
The first injection teaches your immune cells to recognize the virus; is accelerating. With the second shot, there are more immune cells ready and waiting to launch a major defense. Muscle pain and fever come from inflammation; your immune cells are sending an alarm in the form of chemicals called cytokines.
“Your immune system is ‘primed’ with dose one. You are being “boosted” with dose two. This reflects your body’s quick response. … Your body is seeing it a second time and remembering it, and it is developing the powerful immune response it needs to respond to infection. “
Notably, not everyone experiences side effects after the second dose of the vaccine. This, however, should not mean that the vaccine is not working. People react differently to the COVID-19 vaccine and some people are fortunate not to experience any serious symptoms. Suffice it to say that if you don’t experience any side effects, you can rest easy knowing that your body is still developing a strong immune response to the virus.
If you have a vaccination appointment coming up, the CDC notes that people should avoid taking pain medications like Tylenol or Motrin in advance, as this could affect the vaccine’s effectiveness. And while it is not an official CDC directive, some health professionals are warning people to avoid drinking alcohol before injections.
“Most of the available data on how alcohol affects the immune system and responses to vaccines suggests that, in general, people should avoid excessive alcohol consumption at the time of vaccination,” said Professor Christopher Thompson of Loyola University Maryland Healthline recently. “Ideally, this would be avoided for at least a week before the first dose and a month after the second dose.”
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A longtime Mac user and Apple enthusiast, Yoni Heisler has been writing about Apple and the technology industry in general for over 6 years. His writings were published in Edible Apple, Network World, MacLife, Macworld UK and, more recently, TUAW. When not writing and analyzing the latest happenings with Apple, Yoni enjoys watching Improv shows in Chicago, playing football and cultivating new addictions to TV shows, the most recent examples being The Walking Dead and Broad City.