Why Experts Are Concerned About Pregnant People Taking Merck’s Antiviral Pill for COVID-19

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  • While the FDA authorized a new pill to treat COVID-19, the organization remains concerned it could impact pregnant people.
  • One of the major concerns is that it has the potential to cause mutations in human DNA in developing fetuses.
  • The drug creates compounds that are similar to one of the building blocks of RNA, which is the genetic code inside the novel coronavirus.

As the Omicron variant of the coronavirus continues to spread, a COVID-19 pill to treat symptoms offers hope.

The Food and Drug Administration (FDA) narrowly authorized the use of a new COVID-19 pill from Merck. But the FDA has gone so far as to say it is hesitant to recommend the pill during pregnancy, citing that it may not be safe for developing fetuses.

While nothing has been definitively determined at this point, experts are leaning toward agreeing with the FDA’s hesitancy, adding that the safest way for pregnant people to stay safe is to get the COVID-19 vaccine.

“Certainly, the Merck pill has raised a lot of concerns, including from a number of the FDA advisory committee, concerning reproductive health and whether women who are pregnant, or thinking of becoming pregnant, should take it,” said Dr. William Schaffner, professor of preventive medicine in the department of health policy as well as professor of medicine in the division of infectious diseases at the Vanderbilt University School of Medicine in Nashville, Tennessee.

Why is the FDA concerned about the Merck pill and pregnant people?

The pill, called molnupiravir, performed well in clinical trials — so well, in fact, that the trial stopped early to expedite FDA approval.

But since the flurry of excitement, new reports have curbed enthusiasm and expectations, as published research reports that the pill may not be as effective as originally thought.

Initially, molnupiravir was thought to decrease COVID-19 hospitalizations by 50 percent, though that figure has recently been decreased to 30 percent.

While it is still very early to know hard facts about the Merck pill, one of the major concerns is that it has the potential to cause mutations in human DNA in developing fetuses.

The drug creates compounds that are similar to one of the building blocks of RNA, which is the genetic code inside the coronavirus.

“There are several [members of the FDA advisory committee] outspoken saying [the Merck pill] should not be available for pregnant women because of the uncertainty,” said Schaffner.

The pill is meant to be taken after experiencing COVID-19 symptoms. The clinical trial was given to participants in four capsules, twice a day for 5 days.

Once the pill is in the bloodstream, it blocks the ability of the virus to replicate. The drug incorporates itself into the viral RNA, which causes mutations to the RNA genetic code and thus stops the virus’s ability to function.

Experts are concerned that because the drug works by confusing the coronavirus RNA, it could have a similar effect on human DNA.

But experts stress more information is needed.

“It’s not that [the FDA] is convinced that the pill will interfere with the reproductive DNA, but they are sufficiently concerned to say that it is prudent that it not be given to pregnant women,” said Schaffner.

How antiviral pills can help fight COVID-19

While not necessarily the miracle drug it was thought to be, the molnupiravir pill may still be a turning point for COVID-19 treatment.

In addition to this pill from Merck, Pfizer has been developing its own antiviral pill for COVID-19.

That treatment is called Paxlovid and, so far, it has been found to decrease the severity COVID-19 and is also likely to work against the Omicron variant.

Pfizer said in its trial of unvaccinated people, those taking the antiviral pill had 89 percent reduced risk of hospitalization and death when taken within 3 days of symptoms.

Whether or not the Pfizer pill interferes with human DNA is also yet to be determined.

“Pfizer’s pill does not have the same concern [as Merck’s] — at least not yet, as far as we know. Other manufacturers are working on antivirals as well,” said Schaffner.

How should pregnant people protect themselves against COVID-19? 

One of the current treatments for COVID-19 uses the injection or infusion of monoclonal antibodies.

In November, the FDA authorized the use of monoclonal antibodies to be administered for the treatment of mild to moderate COVID-19 in people ages 12 and older. These laboratory-made proteins work by mimicking the immune system’s ability to fight off viruses.

According to cancer research center Fred Hutch, monoclonal antibodies have been shown to reduce the risk of hospitalization by 85 percent.

“Bottom line, the Merck drug is not ready for prime time when it comes to pregnancy,” said Dr. Ashley Roman, vice chair for clinical affairs–obstetrics and service chief of obstetrics in the department of obstetrics and gynecology at NYU Langone Health. “The Merck product specifically has raised a couple of concerns about efficacy. It does not appear to be as efficacious as monoclonal antibodies.”

Of course, the number one way to stay protected from COVID-19 is to get vaccinated.

Roman added, “From what we know over the past year of experience with the various vaccines to prevent COVID, the vaccine is safe to be administered during pregnancy, regardless of trimester. What we’re recommending for our patients, and the most effective thing women can do to prevent severe illness in COVID, is to be vaccinated and boosted if the timing is appropriate.”

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