Are COVID-19 jabs safe to administer during pregnancy?

Pregnant or lactating individuals can safely receive a COVID-19 vaccine, with the reactions experienced not significantly different from that of their nonpregnant counterparts, according to data from an ongoing study.

The reactions are well within what is expected from a vaccine, said senior study author Dr Linda Eckert, a professor of obstetrics and gynaecology at the University of Washington (UW) School of Medicine in the US.

A total of 17,525 individuals (mean age 33.6 years, 99.7 percent women, 87.6 percent White) with known pregnancy status and received at least one dose of a COVID-19 vaccine comprised the study population. They were divided into three groups, as follows: those who were pregnant (n=7,809, 44.6 percent), those who were lactating (n=6,815, 38.7 percent), and those who were neither pregnant nor lactating but planning pregnancy in the near future (n=2,901, 16.5 percent) at the time of their first vaccine dose.

The majority of the participants received the Pfizer-BioNTech BNT162b2 vaccine (61.9 percent), while more than a third had the Moderna mRNA-1273 vaccine (37.8 percent). Most resided in the US, were employed in healthcare, and had completed some college education.

Postvaccination reactions after the first dose occurred in 97 percent of the population (n=17,005), with the most common being pain at injection site (91.4 percent) and fatigue (31.3 percent). The frequency of reactions after the second dose was notably higher than after the first dose (eg, 69.2 percent had fatigue after the second dose), but with similar distribution of symptoms.

Fever developed in 499 participants (including 131 pregnant individuals) after the first dose and in 3,293 (including 1,051 pregnant individuals) after the second dose. The average maximum self-reported temperature was 38.1 °C.

On analysis, pregnant participants were less likely to develop postvaccination reactions compared with individuals who were neither pregnant nor lactating. For example, the odds for developing fever were 52–56 percent lower after the second dose of the BNT162b2 (odds ratio [OR], 0.44, 95 percent confidence interval [CI], 0.38–0.52; p<0.001) or the mRNA-1273 (OR, 0.48, 95 percent CI, 0.40–0.57; p<0.001) vaccine. [JAMA Netw Open 2021;4:e2121310]

Meanwhile, any obstetrical symptoms among pregnant participants occurred in 4.4 percent after the first dose and in 7.5 percent after the second dose. Of the 6,586 pregnant individuals who had received their second vaccine dose at the time of data analysis, 94.8 percent were still pregnant, 4.3 percent had delivered, and 0.7 percent had miscarriages.

In the lactating group, interrupted breastfeeding after vaccination occurred in 2.3 percent of participants after the first dose and in 2.2 percent after the second dose. Milk supply declined for less than 24 hours in about 5.0 percent and 7.2 percent of participants following the first and second dose, respectively.

“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,” she added.

One strength of the study was the ability to compare vaccine reactions and perceptions in pregnant and lactating individuals vs those of similar age and fertility intentions who were neither pregnant nor lactating. However, the study population was drawn from a convenience sample with self-reported reactions and with limited perinatal outcome assessment. It also largely consisted of healthcare workers, reflecting the first wave of vaccination.

“As a result, our findings may be biased and not generalizable to all populations. In addition, there is potential participant overlap between our study and similar [research]. Further studies are ongoing to investigate outcomes after receipt of COVID-19 vaccines among pregnant and lactating individuals,” according to Eckert.