accine side effects.
Much of the vaccine hoopla is focused on the December 10 FDA meeting and subsequent vaccine distribution. Much less attention has focused on informing, and preparing, the public on what to expect once you actually get the vaccine. I think this is a mistake. We must be transparent about what people should expect.
After vaccination, close to 100% of people will experience a local symptom. This includes pain at injection site, redness, and some swelling. I don’t think any of us are surprised about these, considering the vaccination comes with a needle.
A much smaller amount of people will experience intense (defined as preventing daily activities) side effects. In the Moderna trial, these included fatigue in 9.7% of participants, muscle pain in 8.9%, joint pain in 5.2%, and headache in 4.5%. Pfizer/BioNTech vaccine trial, side effects included fatigue (3.8%) and headache (2%). Some participants described that they “felt similar to a severe hangover” or “slight flu symptoms”. Together, 2% of participants got a fever. Chances of side effects are higher when you get the second dose (30 days after the first dose). No other severe systemic events were reported. In other words, 19,000 people did not have a severe event from the Pfizer/BioNTech vaccination.
Why the more intense side effects? The Pfizer vaccination is made up of small strands of mRNA. Basically, it’s a bunch of instruction manuals that need to be sent to your cells. However, in order for them to get there they must be transported in tiny fat bubbles (see picture labeled "lipid nanoparticle"). Some people may have some intense side effects from the fat bubbles.
The higher rate of intense reactions is more than people are typically accustomed to. However, the side effects are temporary. The side effects are normal. And, actually, side effects are a good sign that your immune system is working.
With COVID19 killing 1 in 200 people infected and the possibility of returning to a normal life, this is a small sacrifice to pay. We know that these vaccines are 95% effective. So, if you’re one of the unlucky few with side effects, have confidence in knowing that the vaccine will work.
As one immunologist said, “take Tylenol and suck it up for a day”.