Are irregular periods a side effect of COVID-19 vaccines? Irregular periods include heavier bleeding than normal, early periods, late periods and similar changes.
Right now, there’s no scientific evidence that suggests COVID-19 vaccines are making periods irregular.
“Some women have reported on social media that the period after a COVID-19 vaccine was different, or changed in some way from what they usually expect,” says OB-GYN Jennifer Griffin Miller, MD, MPH. “This was not identified in the clinical trials of the vaccines. There’s also no biological mechanism, based on how the vaccines work, that would explain these occurrences.”
Your period can fluctuate for many reasons, including diet, stress, exercise, illness and pregnancy. Nebraska Medicine OB-GYN Karen Carlson, MD, writes about how pandemic stress can affect periods. Oral contraceptives and other medications can also change periods, especially if they change hormone levels.
Abnormal periods will also happen by chance after people receive the COVID-19 vaccine. That doesn’t necessarily mean the vaccine caused the abnormal period. They could be related, but it’s too soon to say for sure.
“It’s not uncommon for women to experience an atypical cycle over the course of a year,” says Dr. Griffin-Miller. “When millions of menstruating women are receiving the vaccine, the timing could certainly be coincidence.”
Vaccines sometimes do create an immune response that you can feel. Often people report fevers, body aches, headaches and pain at the site of injection. These side effects often go away in a few days. See why it helps to schedule your mammogram around a vaccine.
If you’re experiencing persistently abnormal periods, seek care. Call 800.922.0000 to schedule an appointment with an OB-GYN who can help.
Can “vaccine shedding” cause side effects in unvaccinated people?
There have been reports of “vaccine shedding” causing side effects to people who have not been vaccinated. The idea is that someone who has been vaccinated is shedding spike protein to those around them who have not been vaccinated.
“We have no data to indicate that contact with somebody who has been vaccinated affects menstrual cycles,” says infectious diseases expert James Lawler, MD, MPH.
The vaccines can’t give you COVID-19. Vaccines do not contain SARS-CoV-2, the virus that causes COVID-19. And the spike protein itself can’t shed.
“Recipients of the vaccines do not ‘shed’ significant amounts of coronavirus spike protein after vaccination,” says Dr. Lawler. “Spike protein is primarily made locally in muscle where the vaccine is administered and may possibly be seen in low levels in the blood. But it should not be shed in significant quantity in respiratory or other secretions.”
If someone is actively infected with COVID-19, though, they are shedding and contagious. “We know that people with COVID-19 shed large amounts of virus from respiratory secretions,” says Dr. Lawler.
Shedding can’t happen without a live vaccine. The mRNA vaccines – Pfizer and Moderna – are not live vaccines and do not replicate. Even in live vaccines, vaccine shedding is limited. Both the Johnson & Johnson and AstraZeneca vaccines can’t replicate, so there’s no way they can shed.