Omicron Brings New Risks to Unvaccinated Pregnant Women

Left out of early vaccine trials and faced with confusing messages and misinformation on the dangers to their unborn children, a disproportionately large number of pregnant women have steered clear of Covid shots. About 75% of expectant mothers in the U.K. and about 65% in the U.S. remain unvaccinated, making them among the groups most at risk of getting infected and being exposed to severe forms of the disease as the fast-spreading omicron strain sweeps across the globe.

At least 17 pregnant women and four babies have died from Covid-19 in England between May and October, figures published last week show. Over that period, 98% of pregnant women admitted to intensive care were unvaccinated. Also, since July, one in five Covid patients receiving treatment in England through a special lung-bypass machine was an unvaccinated expectant mother.

"The uptake of vaccination in pregnant women is depressingly low and significant numbers of women have come to serious harm as a result of this," Chris Whitty, the U.K.'s chief medical adviser, told lawmakers Dec. 16. "Pregnancy's a period of vulnerability. We really should have made that point even clearer earlier on."

Information on this group remains sparse across much of Europe. While real-world data over the spring and summer showed the shots are safe and effective for them, the absence of pregnant women in early vaccine tests resulted in hesitancy that's hard to shake off.

Take Antonia, for instance. The London lawyer, who's seven months pregnant, got her first jab before she was pregnant but struggled over her second, post-pregnancy inoculation. Vaccine centers didn't have reassuring answers to her questions, and she got the shot with a lot of trepidation.

"I was so nervous I booked the vaccination so many times and canceled it," said Antonia, 38, who's having her second child and didn't want to reveal her last name. "I just thought 'it's not my life here, it's somebody else's life I'm making decisions about.'"

Vaccine hesitancy compounds the immuno-compromised state brought on in pregnant women by their bodies' efforts to grow the foetus. The risk of severe Covid-19 is particularly acute in the third trimester and increases the prospect of premature and still birth. It also raises the possibility of long-term health issues for the expectant mother.

Many maternal-care specialists saw this coming, said Pat O'Brien, vice president of the Royal College of Obstetricians and Gynaecologists.

"We were worried from day one that it might be worse in pregnant women than other people because other respiratory viruses have been, like SARS and flu," said O'Brien. "We must learn the lesson that pregnant women should be included when it's safe to do so at an early stage in all new drug and vaccine trials."

At least one drugmaker tried. In February, Pfizer initiated a mid-stage trial in pregnant women before moving to advanced-stage testing in June. But low enrollment and the ethical dilemma of giving placebos to expectant mothers when vaccines were already recommended saw the trial halted with less than 10% of its target 4,000 volunteers.

While the company still plans to publish the data, the low participation may limit any takeaways.

"I think this has opened the eyes and the potential for regulators and manufacturers to initiate pregnancy studies earlier," said Alejandra Gurtman, vice president of vaccine research and development at Pfizer.

The problem is deciding when it's alright to include pregnant women. Vaccines must be shown to be safe in the general population before authorities can expose unborn children.

"If we weren't in such a pandemic 'all-out' mode, we probably could have started a trial early on in pregnant women," Peter Marks, head of the U.S. Food and Drug Administration's vaccine program, said in a Bloomberg interview. "If I were drawing this up from scratch again, probably within a few months after we had safety data flowing in from the phase 3 clinical trials we probably could have initiated a trial in pregnant women."

Some of the reticence stems from history. Although not a vaccine, in the 1950s a drug called thalidomide was prescribed for early-pregnancy nausea. It severely impacted limb development in children and affected more than 10,000 babies, half of whom died.

A lack of information on the vaccine's safety in the first trimester and a surfeit of misinformation on social media, especially on the impact vaccines could have on a growing baby and on fertility, haven't helped. Over the summer, a "news" item went so far as to suggest vaccines provoked miscarriages.

Laura Magee, an obstetric physician in the U.K., said the similarity between a protein in placental development and the spike protein on the virus raised concerns antibodies from the vaccine could attack the placenta, though studies have shown this isn't the case.

"There's no basis whatsoever for any concern that the antibodies that you make as a result of accepting the vaccination will interfere with placental development," she said.

Clinical trials have also shown that the shots had no impact on fertility. The same is true for birth outcomes, stillbirths or low birth-weights, data from the U.K. Health Security Agency showed.

Such assurances have failed to make a big difference, suggesting the need for better communication and an earlier involvement of expecting mothers.

The U.K. drugs regulator says it's looking into "how developers of new medicines and vaccines could improve inclusion of pregnant women in studies." One way would be to start trials when early tests have established safety and advanced trials are underway, as Pfizer did with adolescents.

For Ruth Faden, a bioethicist at Johns Hopkins who's involved in the working group PREVENT -- which drafted guidance on vaccines in epidemics and pregnant women in 2019 -- Covid-19 shows why some serious rethinking is critical.

"The experience of this pandemic, which has gone so wrong for pregnant women, I'm hopeful is enough to at least in the epidemic-vaccine space result in some changes going forward," she said.