How do you spot an adverse reaction following a COVID-19 vaccine? Experts explain

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Fact or Fiction: How do you spot an adverse reaction following COVID-19 vaccine? Experts explain.
WATCH: Should you be alarmed if you develop a fever? What about unexplained bruises? Experts break it down. – May 18, 2021

Many of us know someone who has no intention of taking the COVID-19 vaccine.

Controversy surrounding the drug that was manufactured in record speed continues to balloon as the pandemic continues.

While some say the emerging mRNA technology is the reason behind their hesitancy, others stress it’s the potential side effects they’re worried about.

“Most of the side effects are a nuisance at most,” says Dr. Ali Abdul-Sater, professor and immunologist at York University.

Abdul-Sater says there are two most common types of side effects that you should expect, and not be alarmed by, following the COVID-19 vaccine.

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The first set of side effects are ‘local’, presenting themselves near the injection site within 24-48 hours. These include:

  • pain
  • redness
  • swelling

The second kind of side effects are “systemic,” says Abdul-Sater, or ones that affect the whole body. You can expect:

  • headaches
  • fatigue
  • muscle pains, joint pains, and aches
  • chills (more common after second dose)
  • mild fever (more common after second dose)
  • nausea (more common after second dose)

Numerous reports have surfaced of a few additional symptoms following the AstraZeneca shot, including vomiting or enlarged lymph nodes. These are not very common, but are still not alarming, according to Abdul-Sater.

“Everyone’s immune system is a little bit different,” said Stacey Smith?, professor at the School of Epidemiology and Public Health and the Department of Mathematics and Statistics at the University of Ottawa.

“Some people are healthier than others,” she said. “Some people have different genetic histories than others. We’re all going to react [to the vaccine] a little bit differently.”
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However, those fully inoculated may be alarmed by the severity of their symptoms.

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“There tends to be a little bit of a difference between when you get your first dose and when you get your second dose,” said Dr. Gerald Evans, infectious disease specialist at Queen’s University.

“The second dose inevitably produces, in some people at least… more intense local and sometimes systemic symptoms.”

These are very short-lived symptoms that happen both in the mRNA and viral vector vaccines, but are still not concerning, according to Evans.

In fact, they’re a sign your immune system recognizes the spike protein it saw the first dose, and is robustly reacting to it.

“Its a reflection that the vaccines are doing their job, that they’re actually working,” said Evans.

Because the side effects are very similar between one vaccine brand to the next, Adul-Sater and Evans say shopping for a different vaccine won’t make much of a difference.

So when should you be concerned?

As the vaccine continues to get administered to masses of people everyday, experts have gradually learned more about adverse reactions.

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So far, there are two known adverse events following the COVID-19 vaccine. The first is an allergic reaction that first emerged after Moderna and Pfizer inoculations.
Absul-Sater says worrying side effects will present themselves within 15 minutes, and they include:

  • hives
  • mouth swelling
  • difficulty breathing
  • hoarse voice
  • wheezing

Those most at risk, according to Abdul-Sater, are individuals who are allergic to Polyethylene glycol or Polysorbate 80, which are used commonly in things like toothpaste and cosmetics.

But whether you know if you’re allergic or not, this reaction can be robustly treated on site, according to Evans.

The other known adverse event is blood clotting, which presents itself more commonly following AstraZeneca shots, and a bit more rarely following the Johnson & Johnson vaccine.

Alarming side effects may appear anytime over the course of three weeks, according to Evans, and include:

  • blurred vision
  • severe headaches that don’t go away
  • unexplained bruises
  • swelling in legs
  • shortness of breath

It is still unclear who is most at risk of blood clots.  But Evans says, at first, it seemed to affect younger people, which is why an age threshold of 55+, and then 40+, was put up. The overall risk in that category seems to be 1 in 50,000.

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There is a theory as to why this is happening, though, which Evans says appeared in viral vector vaccine studies 15 years ago and is being considered in Denmark.

Evans says vaccines are supposed to be injected into the muscle, not the vein. However, the studies suggest that if the needle were to accidentally poke a blood vessel and deposit some vaccine inside, a blood clot might form.

Evans says a remedy for this could potentially be sticking the needle in the arm, pulling it back slightly, and then administering the dose. This makes sure that the needle isn’t inside a blood vessel when the dose is moving out of the syringe.

It is still unclear whether this could actually work. Either way, Evans says medical experts have figured out an effective treatment plan when someone presents symptoms of a blood clot post-vaccine.

The individual is taken for some common blood tests and then given special blood thinners as a treatment option.

Smith? stresses the large scale at which these vaccines are being administered is what gives the public the impression that these adverse events are common.

“Your chance of getting blood clots from COVID-19 is way higher than from the vaccine,” Smith? reassures.

“I think also, we as humans, are not very good at risk assessment. We sort of think something is new and scary, and therefore I’ll avoid it, even if the chances are really, really tiny of something going bad. But then we do things that are completely risky, like drive a car…because its familiar.”

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“So we’re not good at assessing risk, we’re good at assessing what’s comfortable,” she noted.

Smith? stressed the importance of getting the COVID-19 vaccine far outweighs any risk of adverse event.

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