Objectives
To describe the severity of maternal infection when the Omicron
SARS-CoV-2 variant was dominant (15/12/21-14/01/22) and compare outcomes
among groups with different vaccination status.
Design
Prospective cohort study
Setting
UK consultant-led maternity units
Participants
Pregnant women hospitalised with a positive SARS-CoV-2 PCR test up to 7
days prior to admission and/or during admission up to 2 days after giving
birth.
Main outcome measures
Symptomatic or asymptomatic infection. Vaccination status. Severity of
maternal infection (moderate or severe infection according to modified WHO
criteria). Mode of birth and perinatal outcomes.
Results
Out of 1561 women admitted to hospital with SARS-CoV-2 infection, 449
(28.8%) were symptomatic. Among symptomatic women admitted, 86 (19.2%) had
moderate to severe infection; 51 (11.4%) had pneumonia on imaging, 62
(14.3%) received respiratory support, and 19 (4.2%) were admitted to the
intensive care unit (ICU). Three women died (0.7%). Vaccination status was
known for 383 symptomatic women (85.3%) women; 249 (65.0%) were
unvaccinated, 45 (11.7%) had received one vaccine dose, 76 (19.8%) had
received two doses and 13 (3.4%) had received three doses. 59/249 (23.7%)
unvaccinated women had moderate to severe infection, compared to 10/45
(22.2%) who had one dose, 9/76 (11.8%) who had two doses and 0/13 (0%) who
had three doses. Among the 19 symptomatic women admitted to ICU, 14 (73.7%)
were unvaccinated, 3 (15.8%) had received one dose, 1 (5.3%) had received
two doses, 0 (0%) had received 3 doses and 1 (5.3%) had unknown vaccination
status.
Conclusion
The risk of severe respiratory disease amongst unvaccinated pregnant
women admitted with symptomatic SARS-CoV-2 infection during the Omicron
dominance period was comparable to that observed during the period the
wildtype variant was dominant. Most women with severe disease were
unvaccinated. Vaccine coverage among pregnant women admitted with SARS-CoV-2
was low compared to the overall pregnancy population and very low compared
to the general population. Ongoing action to prioritise and advocate for
vaccine uptake in pregnancy is essential.
SUMMARY BOX
What is already known on this topic
In non-pregnant adults, growing evidence indicates a lower
risk of severe respiratory disease with the Omicron SARS-CoV-2
Variant of Concern (VOC).
Pregnant women admitted during the periods in which the
Alpha and Delta VOC were dominant were at increased risk of
moderate to severe SARS-CoV-2 infection compared to the period
when the original wildtype infection was dominant.
Most women admitted to hospital with symptomatic SARS-CoV-2
infection have been unvaccinated.
What this study adds
One in four women who had received no vaccine or a single
dose had moderate to severe infection, compared with one in
eight women who had received two doses and no women who had
received three doses
The proportional rate of moderate to severe infection in
unvaccinated pregnant women during the Omicron dominance period
is similar to the rate observed during the wildtype dominance
period
One in eight symptomatic admitted pregnant women needed
respiratory support during the period when Omicron was
dominant