Delta Variant Warning for Unvaccinated Pregnant Women
The Delta variant is particularly dangerous for pregnant women.

Unvaccinated pregnant women infected with the Delta variant run a greater risk of contracting severe COVID-19, according to a UK study of 3371 pregnant women admitted to the hospital with symptomatic COVID-19. 

The study, conducted by the UK Obstetric Surveillance System (UKOSS), found that 24% of pregnant women admitted in the first wave had moderate or severe disease, compared to 36% of those infected with the Alpha variant and 45% with the Delta variant. 

The number of unvaccinated pregnant women admitted to the hospital has been on the rise, which Marian Knight, Professor of Maternal and Child Population Health, University of Oxford and chief investigator of the study called ‘concerning’. 

“Around 200 pregnant women were admitted to hospital with COVID-19 last week. I cannot emphasise more strongly how important it is for pregnant women to get vaccinated in order to protect both them and their baby,” said Knight.

Worsening illness and post-birth complications for mother and baby  

Babies born to mothers in the Alpha and Delta periods of the pandemic were more likely to require admission for neonatal care compared to the first wave.

Pregnant women are particularly vulnerable to becoming severely ill from COVID-19 compared to non-pregnant women of a similar age, according to the WHO. Around one in ten women admitted to the hospital with symptoms of COVID-19 require intensive care, and one in five pregnant women give birth prematurely. 

Women admitted during the period when the Alpha variant was dominant in the UK were more likely to require respiratory support, have pneumonia, and be admitted to intensive care than women admitted in the first wave. 

Women admitted during the Delta period had an even further increase in risk, compared to those in the Alpha period, with a greater proportion having pneumonia.

Babies born in the Alpha period were more likely to require admission for neonatal care compared to the first wave, with a similar proportion for babies born to mothers in the Delta period.

Vaccinating pregnant women offers effective protection against COVID-19 

Women in Bongouanou, Côte d’Ivoire, during a prenatal medical consultation.

Protecting both mothers and babies with the vaccine does have its benefits, with data from the study showing that COVID-19 vaccinations offered effective protection for pregnant women against severe illness and other risks. 

Vaccination data has been collected since 1 February 2021. Of the 742 women admitted since that date, only four had received a single dose, and none had received both doses. 

This means that more than 99% of pregnant women admitted to the hospital with symptomatic COVID-19 are unvaccinated. In comparison, 60% of the general population admitted to the hospital with COVID-19 are unvaccinated.

During this time, at least 55,000 pregnant women received one or more doses of a COVID vaccine in the UK. 

‘It is extremely good news that so few vaccinated pregnant women have been admitted to hospital with COVID-19,” said Knight, who advised unvaccinated pregnant women to remain cautious and continue social distancing measures.

 “Until they are vaccinated, pregnant women must continue to be extremely attentive to social distancing measures including mask-wearing, 2m distancing and meeting outdoors where possible,” she added.

“This study shows that very few pregnant women are admitted to hospital with COVID-19 after they have received a vaccine,” said Nicola Vousden, first author of the study. “Other studies have shown that women who have received a vaccine pass on antibodies to their babies, so the benefits of vaccination to both pregnant women and their babies are clear.”

The Royal College of Obstetricians and Gynaecologists and the Royal College of Midwives recommend that unvaccinated women who are pregnant or considering pregnancy get their vaccine as soon as possible, and book their second doses once eligible. 

UK trial to explore optimal vaccination schedule

Meanwhile, a UK clinical trial has been launched in order to alleviate concerns about the vaccine and determine an optimal vaccination schedule to protect pregnant women against COVID-19. 

The clinical trial, called Preg-CoV, will help determine the best gap between doses for pregnant women and explore in greater detail the potential side effects and impact on babies, which researchers hope will offer reassurance for expecting mothers and those thinking of becoming pregnant.  

“We really do need to make sure that when we are vaccinating pregnant women we are doing so in the most optimal way to ensure they are best protected,” said Paul Heath, chief investigator of the trial and professor of paediatric infectious diseases at St. George’s University of London.

In the first phase of the Preg-CoV trial, the team hopes to recruit 600 pregnant women between the ages of 18 and 44 across 13 sites in England. 

Two groups of 200 unvaccinated women at different gestation times will be randomized with either a Moderna or Pfizer vaccine and will be given their second dose four to six weeks or at 8-12 weeks after the first dose. 

Participants will not know which COVID jab they are given, added Heath. 

A third group of 100 pregnant women will be given one dose of a COVID shot at 28-34 weeks gestation, with the second dose of the same vaccine after delivery. 

The fourth group of 100 pregnant women will have already had their first dose of any COVID vaccine before or very early in pregnancy, and will get their second dose of the same vaccine during the trial. 

All women recruited will have follow-up visits and blood tests, and will fill in an electronic diary to help researchers monitor any adverse side effects. The team will also track outcomes for the babies up to 12 months of age to explore safety and impact on their development.

Experts note that there is no evidence of harm to babies, as the shots are beneficial in reducing chances of pre-term birth or stillbirth, and the antibodies can cross the placenta, protecting the child against COVID. 

Pregnant women should be included in future vaccine trials  

Heath said the trial would “fill in the gaps” in current knowledge about vaccinating pregnant women.

While the UK COVID vaccination program has been a success, uptake has been slow among pregnant women. 

“Pregnant women are still concerned because pregnant women were not included in initial COVID vaccine trials,” said Asma Khalil, lead obstetrician for the trial.

“I think there will be some lessons learned from this pandemic. And one of them is that we should consider including pregnant women at a relatively early stage for vaccine trials.”


Image Credits: Elizabeth Poll/MMV, USAID/Flickr, UN Photo/Hien Macline.

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