Robust real-world data from the United States – where over 160,000 pregnant women have been vaccinated mainly with mRNA vaccines, such as Pfizer-BioNTech and Moderna – have not raised any safety concerns.
Therefore, the JCVI advises that it is preferable for the Pfizer-BioNTech or Moderna mRNA vaccines to be offered to pregnant women in the UK, where available.
The UK Health Security Agency (formally Public Health England) have reported that more than 82,000 pregnant women in England have received at least one dose of COVID-19 vaccination and Public Health Scotland have reported that more than 19,000 pregnant women have received a vaccine, with no serious adverse effects recorded.
The initial clinical trials which showed that COVID-19 vaccines are safe and effective did not include pregnant women. As the COVID-19 vaccines were not tested in pregnant women, we cannot say for sure that they work as well in pregnant women as they do in other adults. However, more recent studies showed that pregnant women who had the vaccine made antibodies against COVID-19, suggesting that the vaccine is effective in pregnancy. Recent studies also showed that pregnant and non-pregnant women had similar mild side-effects from vaccination.
COVID-19 vaccines do not contain ingredients that are known to be harmful to pregnant women or to a developing baby. Studies of the vaccines in animals to look at the effects on pregnancy have shown no evidence that the vaccine causes harm to the pregnancy or to fertility.
The COVID-19 vaccines that we are using in the UK are not ‘live’ vaccines and so cannot cause COVID-19 infection in you or your baby. Vaccines based on live viruses are avoided in pregnancy in case they infect the developing baby and cause harm. However, non-live vaccines have previously been shown to be safe in pregnancy (for example, flu and whooping cough). Pregnant women are offered other non-live vaccines, such as those against flu.
Studies have shown that protective antibodies from vaccination do cross the placenta, helping with the baby’s immunity to COVID-19. We know that catching COVID-19 during pregnancy can cause severe illness in a pregnant woman, especially in the third trimester – that’s why we recommend the COVID-19 vaccine in pregnancy.