One of the two COVID-19 vaccines approved for use in the United States has caused facial swelling for people with cosmetic facial fillers.

According to information presented during this month’s meeting of a Food and Drug Administration (FDA) panel on Moderna’s COVID-19 vaccine, two of four serious adverse events related to the vaccine in a phase three clinical trial happened to patients with the fillers, which are gel-like substances injected beneath the skin to help create a smoother or fuller appearance in the face.

One trial participant received the injection two weeks prior to being vaccinated. The other received it six months prior to the shot. Both experienced facial swelling. The swelling was related to the vaccine, according to Moderna and an investigator.

“It is possible the localized swelling in these cases is due to an inflammatory reaction from interaction between the immune response after vaccination and the dermal filler. This phenomenon has been reported after natural infection (e.g., after an influenza-like illness),” the administration said in its briefing document to the Vaccines and Related Biological Products Advisory Committee.

Dr. Shirley Chi, a dermatologist, told ABC 7 that the reaction to the vaccine was immunological.

“Your immune system which causes inflammation is revved up when you get a vaccine, that’s how it’s supposed to work. So it makes sense that you would see an immune response in certain areas where they see some substance that is not a naturally occurring substance in your body,” she said.

Chi is recommending that people who have the fillers still get the vaccine, since both patients who experienced swelling were successfully treated for the side effect.

The committee recommended the FDA issue emergency use authorization for Moderna’s vaccine after hearing about the trial and other matters. The FDA issued the authorization on Dec. 18.

No dermal filler-related side effect was noted in the briefing document for the other vaccine, from Pfizer and BioNTech, although officials have said anyone who is allergic to components of either vaccine shouldn’t get them. Moderna advises the same on its website, along with noting that adverse reactions reported in its clinical trial include pain at the injection site, fatigue, headache, and chills.

“Additional adverse reactions, some of which may be serious, may become apparent with more widespread use of the Moderna COVID-19 vaccine,” it states, noting that vaccine providers must complete and submit reports to the Vaccine Adverse Event Reporting System, which tracks adverse vaccine events.Follow Zachary on Twitter: @zackstieber