Despite Paxlovid’s safety and efficacy proven through clinical trials, the drug’s use in pregnant people has not been previously studied with a significant sample size. Last month, Johns Hopkins University School of Medicine published the results of a study showing Paxlovid to be safe for use in pregnancy, for both the fetus and the pregnant person. “It’s the largest study that’s ever been done [on the topic],” says study lead author William Garneau, MD, MPH, an assistant professor of medicine at the Johns Hopkins University School of Medicine. “If there was more use of Paxlovid and more acceptance and more understanding of the drug, women who are pregnant can ask for treatment and prevent complications of COVID.”
What is Paxlovid?
Paxlovid is an antiviral medication made up of two components, nirmatrelvir and ritonavir. Both work together to help reduce the symptoms of a COVID infection in the body. “The nirmatrelvir component is an inhibitor that binds to the Coronavirus protease (enzyme) to stop it from working and preventing the virus from replicating,” explains Mei Chang, PharmD, a clinical pharmacy manager of infectious diseases at Montefiore. “Whereas ritonavir is an HIV protease inhibitor. Although it’s not active against COVID, it does help prevent the breakdown of nirmatrelvir and to allows for that drug level to be a lot higher in the blood for longer without the need for more, sort of like a booster.” Though Paxlovid was initially limited in supply when it was first approved for emergency use, it has since become more easily available to those who are COVID-positive and are a part of a vulnerable population. Since pregnancy is considered an underlying condition, pregnant people are able to receive Paxlovid treatment. The effects of Paxlovid are generally better when taken early in the course of an infection. While there is not a set time period during which Paxlovid can be prescribed, Dr. Garneau explains it’s best to get the medication as soon as possible. “The earlier the better,” Dr. Garneau says. “You’re interfering with the virus and the earlier you intervene, the better your outcome, so it’s not necessarily like it won’t work on day 11 or it will work on day 12. It’s just that you probably missed your window when it’s going to be most effective.”
Paxlovid To Treat COVID During Pregnancy
Before getting emergency use authorization from the FDA, Paxlovid had to go through clinical trials to test its safety and efficacy. As part of the clinical trials, pregnant people were not specifically studied. Researchers at Johns Hopkins University School of Medicine utilized a retrospective approach to study Paxlovid and pregnant people, meaning they weren’t conducting randomized trials but analyzing past information from their database instead. They looked at data from 3,442 people who were diagnosed with mild-to-moderate COVID and seen at one of the hospital’s health systems between March 15, 2020 and Aug. 20, 2022. Of that cohort, 47 pregnant people met the study criteria and were prescribed Paxlovid while also being monitored. The ages of the pregnant people studied hovered around 34 with the median age of their pregnancy being 28 weeks. Most of the participants had received at least their initial COVID vaccine doses and started the Paxlovid treatment within one day of their symptoms starting. “We saw that there was no signal or higher number of miscarriages or women who were having an adverse event either to themselves or their children,” Dr. Garneau says of the results. Dr. Chang says the results of the Johns Hopkins study are promising but more research is needed. “It’s difficult to get some type of data published quickly but many institutions have already been using Paxlovid in pregnant populations with favorable outcomes and minimal side effects,” she says. While the findings were positive in terms of safety, Dr. Garneau says there still must be a risk-benefit analysis when deciding to take Paxlovid while pregnant because nothing is ever 100% safe. “We know that COVID in pregnant women is especially bad,” Dr. Garneau explains. “And so you’re balancing risks. You have to say well, could there be an effect we don’t know about? Sure. Is that worth the risk for me to not get really severe COVID and be hospitalized and lose my pregnancy or end up on a ventilator? That’s another risk.”
Risks of Taking Paxlovid During Pregnancy
While the little research available shows Paxlovid poses minimal risk to pregnant people compared to people who are not pregnant, there are still many questions about the long-term effects of taking the drug while carrying a fetus. In the Johns Hopkins study, some of the participants experienced abnormalities in their pregnancies which Dr. Garneau says were probably not related to their use of Paxlovid. “When you look at 50 pregnancies, some are going to have other things happen during the pregnancy,” Dr. Garneau explains. “It would be abnormal if you just looked at the differences and there were no fetal anomalies or things like gestational hypertension.” Still, it’s hard for researchers to know for sure how much impact Paxlovid had on the outcomes of these pregnancies, though they say it was probably minimal. It’s also important to consider that more research needs to be done on COVID’s long-term effects on pregnancy just the same. Taking Paxlovid also poses a general risk of experiencing side effects, regardless of whether or not you are pregnant, as Chang explains. “Most of the side effects that we see in pregnant patients who are prescribed Paxlovid are very similar to those individuals who are not pregnant,” Dr. Chang says. “Things including diarrhea, maybe some metallic taste has been recorded and a little bit of GI discomfort.”
More Study Needed on Paxlovid and Pregnancy
While the Johns Hopkins study is novel and provides valuable information for pregnant people and their doctors making a decision about treatment for a COVID diagnosis, more research needs to be done on the topic. Dr. Garneau says while their study looked at a significant sample population, one of their most notable drawbacks is that it’s still relatively small at 47. Other limitations include the fact that the information was derived from only the Johns Hopkins Health System and the ethnic and racial make-up of the cohort was not incredibly diverse. “The signals for these things could emerge with more time and numbers of patients,” Dr. Garneau says. “We’re feeling like at this point that the tide is turning and Paxlovid is something we can use. And if there is a signal that is negative, or shows that there is harm, we need to have studies that are continuing to evaluate it.”
