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Risk-benefit analysis of COVID-19 vaccines in pregnant individuals

When the COVID-19 vaccines were first administered to the public in late 2020, its effect was not known in pregnant people as they were not represented during the original clinical trials for testing the shots. Despite that being the standard practice, it left pregnant people doubtful about getting the jab. 

A pregnant woman’s body undergoes several physiological changes to accommodate the fetus. These include:

  1. Suppressing certain parts of the immune system to tolerate a foetus. 
  2. Enhanced expression of blood volume which can strain the cardiovascular system. 
  3. The growing uterus pushes up on the diaphragm, reducing lung capacity. 

So if the virus, that primarily affects the lungs, infects a pregnant person, it would be highly detrimental to them. The virus might also cross the placental barriers and infect the growing foetus leading to other complications such as stillbirth and congenital defects. 

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A CDC report in November, 2021 found that the risk of stillbirth was 2.7 times higher among women who had a COVID-19 diagnosis at delivery during the Delta wave of the pandemic. Another report also found that in the same condition, the risk of maternal mortality increased fivefold. Even before the vaccines were introduced to the public, multiple studies documented that pregnant women were at greater risk than nonpregnant women for severe disease after a COVID-19 infection, resulting in intensive care unit admission, mechanical ventilation, and death. 

Recently, data have shown that the vaccine is not only safe during pregnancy, but also effective. A study published in Science Translational Medicine found that after the second dose of the COVID-19 mRNA vaccine, pregnant women developed neutralising antibodies against the virus and achieved the same immune response to that of nonpregnant women. 

The vaccines may also be able to confer immunity against the virus in the newborns. Since antibodies can be passed from mother to baby through the placenta, the antibodies generated in response to a COVID-19 vaccine are able to offer passive innate immunity to the baby. This is particularly beneficial to the newborn as they are vulnerable during the first few months of life and won’t be eligible for a vaccine for some time. 

A report by Shimabukuro et al. published in the New England Journal of Medicine includes safety results for 35,691 participants aged between 16 to 54 years who identified as pregnant. 54% of the participants received the Pfizer–BioNTech vaccine and 46% received the Moderna vaccine, both of which are mRNA vaccines.

Rates and types of adverse reactions after vaccination among the pregnant participants were similar to that of nonpregnant women, suggesting that the physiologic changes in pregnancy do not affect such reactions. The most common side effect was injection-site pain, with fatigue, headache, and muscle pain reported substantially more often after the second dose. Among the participants who reported a completed pregnancy there was one stillbirth and a few spontaneous abortions and the rest were live births (86.1%). 

A Yale study published on January 4th, 2022. which consisted of 40,000 pregnant individuals, found that COVID-19 vaccination during pregnancy did not result in preterm birth or small-for-gestational-age (SGA) when comparing vaccinated with unvaccinated pregnant people. Preterm birth and SGA are commonly associated with higher risk of infant death and disability. The trimester when the vaccination was received and the number of COVID-19 vaccine doses received were also not associated with increased risk of preterm birth or SGA, the researchers found. 

A recently published EMA (European Medicine Agency) review found that pregnant individuals administered with the mRNA vaccines did not exhibit any signs of an increased risk of pregnancy complications, miscarriages, preterm births or adverse effects in the unborn babies. The review consisted of various studies that included the symptoms in around 65,000 pregnant individuals. The review also highlighted that COVID-19 vaccines are as effective at reducing the risk of hospitalisation and deaths in pregnant people as they are in non-pregnant people. 

There was already a hesitation surrounding vaccination in pregnant individuals even before the pandemic. This is partly due to the misinformation spread via social media platforms and an overall fear over the kinds of effects the vaccines could have on the wellbeing of both the mother and baby. However, recent data have proven that the vaccines offer protection against the SARS-CoV-2 virus in pregnant individuals. Hence, experts stress that the risks of getting a COVID-19 infection during pregnancy outweighs the risks of getting side effects of the vaccine.

Author: Parvathi Nair

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