Michelle Chester, director of employee health services at Northwell Health, prepares the Moderna COVID-19 vaccine at Northwell Health's Long Island Jewish Valley Stream hospital in Valley Stream, N.Y., on Monday, Dec. 21, 2020. (Eduardo Munoz/Pool via AP)

Two patients who had previously had dermal fillers experienced some swelling after receiving the first dose of the Moderna vaccine.

The U.S. Food and Drug Administration reported the reactions at a meeting on Dec. 17.

A dermal filler – not to be confused with Botox, which essentially freezes muscles – is an injectable implant such as collagen or hyaluronic acid used in cosmetic procedures.

Both patients – one 46-year-old and one 51-year-old – had dermal fillers, which the FDA said was a "potential contribution" and presented this as a "possible SAE," or a serious adverse effect, to the vaccine.

But Dr. Julia Carroll, a dermatologist at Compass Dermatology and a lecturer at the University of Toronto's Division of Dermatology, told CTVNews.ca that these kinds of reactions are "so rare."

"Even though they're serious to the individual patient, they're relatively minor," Carroll said. "It's scary when you're in the middle of it as a patient, but it's something that we're well aware of, we have protocols on how to treat them, and everyone gets through it. And many go on to get fillers again."

Carroll adds that this swelling, called delayed filler reaction, is known to dermatologists and can occur after other routine medical events such as a dental procedure, or even by contracting a virus.

While the exact cause of this kind of reaction isn't known, Carroll said dermatologists "try to apply what we know about fillers, what we know about vaccines and viruses and try to make a logical conclusion. So I think it would be an immune trigger. The vaccine is trying to target the immune system, trying to encourage the immune system toward that particular virus, but it's possible that it triggers other immune reactions within your body."

The Government of Canada's website page for the Moderna vaccine does not currently include any mention of dermal fillers or possible related reactions.

In the absence of official guidance from the government, Carroll recommends people hold off on getting fillers prior to getting the vaccine, in between the first and second dose, and for at least two weeks following the second dose.

Some dermatology clinics have reported upticks in cosmetic procedures amid lockdown measures, including Carroll's clinic in Toronto.

"June, July, August was an extremely busy time for us compared to the year before," Carroll said, something she attributes in part to the amount of time people spend video conferencing from home.

"Most people get up in the morning, do their hair, put some makeup on, walk out the door – they probably aren't looking at themselves throughout the rest of the day," Carroll said. "But now you're faced with looking at yourself – and not just a quick, instant shot, but watching yourself emoting and animating throughout the day. And it reveals different things than those quick looks you see in the bathroom."

Despite the fact that some people may have gotten dermal fillers in lockdown, "I wouldn't want anyone to choose to not get the vaccine because they've had a filler in the past," Carroll said. 

"They can always reach out to their dermatologist for advice on how to time things between vaccines and fillers, and we can always figure out a solution for the patient that keeps them safe."