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Wits VIDA scientists find that Covid-19 vaccines are safe during pregnancy


A review of Covid-19 vaccines during pregnancy by Wits scientists shows that vaccination during pregnancy is safe.

The narrative review found that no major safety concerns on the use of mainly messenger RNA (mRNA) Covid-19 vaccines in pregnant women had been identified.

“Although the current Covid-19 vaccines were not tested in pregnant women in the initial clinical trials, information on the safety, immunogenicity and effectiveness of these vaccines has been generated from observational studies,” says lead author of the review, Professor Marta Nunes of the Vaccines and Infectious Diseases Analytics (Wits VIDA) research unit in the Faculty of Health Sciences.

The fact that coronavirus disease during pregnancy is associated with higher risk of stillbirth and preterm birth prompted the review. The review showed that pregnant women mount immune responses to Covid-19 mRNA vaccines comparable to non-pregnant counterparts.

In addition, anti-SARS-CoV-2 IgG [antibodies] were detected in cord-blood following maternal vaccination at concentrations strongly correlated with both maternal antibody levels and the time elapsed since vaccination.

The peer-reviewed evaluation was published in Trends in Molecular Medicine on 3 May 2022.

Messenger RNA vaccines, such as those made by Pfizer and Moderna, use genetically engineered

mRNA give cells instructions of how to make the S-protein that is found on the surface of the Covid-19 virus.

Vector vaccines, on the other hand, such as those made by J&J and AstraZeneca, work by placing a modified version of a virus (a vector) – that is different to the virus that causes Covid-19 – into the cells, which then instructs the body to make copies of the S protein and thus provoke an immune response.

“Vaccination of pregnant women with mRNA Covid-19 vaccines has been shown to be effective in protecting these women against coronavirus disease,” says Nunes.

However, further studies of the effect of other Covid-19 vaccines commonly used in South Africa – and specifically in an African context – are required.

Nunes says that most of the Covid-19 vaccine studies she reviewed were conducted in the US and Israel, and a handful in Europe. But there were no studies on the effect of Covid-19 vaccines on pregnant women in low- and middle-income countries (LMICs).

“The review looked mostly at mRNA vaccines, but on the African continent we use many other types of Covid-19 vaccines, such as J&J and AstraZeneca. Furthermore, the population genetics in LMICs, co-morbidities, and lifestyles differ from other countries, so we need studies on the long-term effects of the vaccines used an African context,” says Nunes.

Covid-19 vaccine research continues a-pace and changes rapidly. Although the Wits VIDA review focused on pregnant women, Nunes says there is some literature from the Global North on the effect of Covid-19 vaccines on breastfeeding women.

These studies suggest that the Covid vaccines are safe to use while breastfeeding and that antibodies are actually found in breast milk, thus possibly conferring some protection to infants.

“In South Africa, the recommendation is for pregnant and breastfeeding women to be vaccinated against Covid-19,” says Nunes.