by University of Washington School of Medicine

Credit: CC0 Public Domain

A survey of more than 17,000 pregnant and lactating individuals who received the COVID-19 vaccine showed that the individuals did not experience symptoms any more severe than their non-pregnant counterparts.

The UW Medicine study, published today in JAMA Network Open, showed "there were not any increased reactions in pregnant individuals beyond what is expected from a vaccine" said Dr. Linda Eckert, a professor of obstetrics and gynecology at the University of Washington School of Medicine and the study's senior author.

"Pregnant people do well with the vaccine," added lead author Dr. Alisa Kachikis.

The findings come a week after the Centers for Diseases Control and Prevention formally recommended that all pregnant women get vaccinated against the virus. The CDC reported that only 23% of U.S. pregnant women were vaccinated as of the end of July. The percentage is even lower among Black and Latina women.

"We hope that this data will be another reassuring piece of information ... about why pregnant individuals need to get vaccinated against COVID-19," Eckert said. "Not only is the vaccine safe, our research shows just how well the vaccine is tolerated in pregnant individuals—which is a common fear I hear from my patients.  In contrast, we are continuing to learn more and more about just how dangerous COVID-19 infections are in pregnancy."

In January 2021, Kachikis set up an online cohort study of women: those who were pregnant or lactating and those who were neither pregnant nor lactating. The women were invited to describe their reactions after receiving at least one dose of a COVID-19 vaccine. By March, 17,525 individuals had responded.

The respondents comprised women who were pregnant (44%) or lactating (38%) and those who stated plans to get pregnant in the near future (15%).

The majority (62%) received the Pfizer vaccine and most of the participants resided in the United States. Respondents reported pain at the injection site (91%) and fatigue (31%), and a mean temperature of 100 degrees Fahrenheit after the shot. A small group (5-7%) reported a decrease in milk supply post-vaccination.

The study supports that women tolerate the vaccine well and that they should be included in clinical trials for other relevant vaccines, Eckert said.

"I'm not surprised but I am pleased by the outcome. It's further evidence that the vaccine is safe and well-tolerated in pregnant individuals."

There are currently 20,000 women enrolled in the study and new respondents continue to post their experiences, Kachikis added. 

The researchers hope to expand the study to other socioeconomic groups and to women not so closely tied to heathcare, as this group was, Eckert said.

"I think this gives a level of evidence to advocate for Phase 3 trials (for pregnant individuals) in the future," Eckert said.

Aside from the CDC vsafe registery, this is the largest U.S. study of this issue. Canada has created a registry based on Kachikis' model. 

More information: Alisa Kachikis et al, Short-term Reactions Among Pregnant and Lactating Individuals in the First Wave of the COVID-19 Vaccine Rollout,
JAMA Netw Open (2021). DOI: 10.1001/jamanetworkopen.2021.21310

Journal information: JAMA Network Open 

Provided by University of Washington School of Medicine