COVID-19: pregnant women depend more on the second vaccine to achieve full immunity

The pregnant women depend more on a second dose of the vaccine against the COVID-19 to achieve full immunity, according to a study published in the journal “Science Traslational Medicine.”

This and other work, which appears in the same publication, find that pregnancy can affect both the way the immune system responds to COVID-19 infections and the currently approved messenger RNA vaccines.

The first study shows that pregnant women depend more on a second dose of the vaccine to achieve full immunity from the vaccine, while the second indicates that infected women who are pregnant with male fetuses have fewer antibodies that fight the virus and changes in the immunity of the placenta.

The results of both investigations help to understand how pregnancy affects immunity against SARS-CoV-2, an important but little studied topic, according to the journal summarizing, which indicates that they could serve to inform future vaccination strategies for mothers pregnant

Throughout the pandemic, few studies and vaccine trials have included groups of lactating and pregnant women, who are vulnerable to the severity of COVID-19.

As a result, researchers have not been sure how pregnancy may affect outcomes for this disease or if different vaccination schedules are needed for these women.

The studies that are now being published “echo the call to action to incorporate women at different stages of pregnancy into clinical trials, thus increasing their representation in vaccine development,” says Cristian Ovies, researcher at the Duke University School of Medicine (USA), and their colleagues in a supporting article that accompanies both papers.

Caroline Atyeo and her team from Harvard University used serology to examine the immune response to the Pfizer and Moderna vaccines in 84 pregnant women, 31 lactating women, and 16 nonpregnant women of the same age.

Although all groups developed antibodies against SARS-CoV-2, other characteristics of the immune response, such as antibody receptor functions, were delayed in pregnant and lactating women after the first dose.

These characteristics only reached the expected levels after the second dose of the vaccine.

These data suggest that pregnancy favors resistance to the generation of pro-inflammatory antibodies and indicate that there is a “critical need” to follow the booster periods after the first dose in this vulnerable population, with the aim of guaranteeing obtaining a complete immunity, according to scientists.

On the other hand, Evan Bordt and his team, also from Harvard, studied samples of maternal and umbilical cord blood to investigate whether the sex of the fetus influences immunity to COVID-19 in 38 pregnant women, who were infected with SARS- CoV-2 during pregnancy.

Mothers carrying male fetuses harbored fewer antibodies against this coronavirus, showed a lower degree of transfer of antibodies to their fetuses, and had differences in the expression of immunity-related proteins.

There is a persistent bias toward an increased prevalence and severity of coronavirus disease in men, and the underlying mechanisms that explain this sex difference remain largely unknown.

Scientists suggest that the new work may provide insight into the increased vulnerability to severe COVID-19 seen in male infants, children, and adults.