Although more pregnant women with symptomatic Covid-19 were admitted during the Omicron wave, the severity of disease and mortality were lower than during the pre-Delta and Delta waves, a new Indian Council of Medical Research (ICMR) study has found.
Previous research demonstrated a higher frequency of severe Covid-19, ICU/HDU (high dependency units) admissions, and maternal deaths during the Delta-dominant wave in Mumbai. However, there was no information on the impact of the Omicron variant on pregnant women.
Researchers from the PregCovid registry team of the ICMR-National Institute for Research in Reproductive and Child Health (NIRRCH) analysed the data of 2,058 Covid-positive pregnant and postpartum women admitted to Mumbai’s BYL Nair Hospital during the pre-delta, Delta and Omicron waves of the pandemic.
Of the 1,143 positive pregnant and postpartum who were admitted between April 2020 and January 31, 2021, there were 27 patients with moderate to severe symptoms and eight died. During the Delta wave from February 1, 2021 to December 10, 2021, of the 597 positive pregnant and postpartum women studied, 86 had moderate to severe symptoms while eight died. In the Omicron wave, of the 318 positive pregnant and postpartum women, two had moderate to severe symptoms and one died.
The PregCovid Registry was launched in April 2020 by ICMR-NIRRCH, the municipal corporation-run hospital and Maharashtra’s Medical Education and Drugs Department to document the impact of Covid on pregnant and postpartum women and their newborns.
A total of 19 tertiary care teaching institutions in the state contributed to the PregCovid registry. The registry has data from more than 9,000 pregnant and postpartum women with Covid and the evidence generated from the registry was useful for making policy decisions on coronavirus vaccination among pregnant women in India.
“Our analysis showed that there was a rapid surge in admissions of Covid-positive pregnant women during the initial four weeks of the Omicron wave, suggesting a different epidemiological pattern from the pre-Delta and Delta waves,” said Dr Niraj Mahajan, from BYL Nair Hospital and the lead author of the study. Findings of the study were published in the International Journal of Gynaecology and Obstetrics, the official journal of the International Federation of Gynecology and Obstetrics (FIGO), in the last week of July.
“We reported seven major differences on the impact of SARS-CoV-2 infection among pregnant and postpartum women during the Omicron wave as compared to the pre-Delta and Delta waves. A greater number of younger women were affected during the Omicron wave compared to the two earlier waves. Although there was a higher proportion of pregnant women with symptomatic Covid-19 admitted during the Omicron wave, the severity of disease and mortality were lower than the pre-Delta and Delta waves,” Dr Rahul Gajbhiye, principal investigator of the PregCovid Registry and corresponding author, told The Indian Express.
“The spontaneous preterm birth rate per 1,000 births was lower during the Omicron wave compared to the two earlier waves. There was a higher spontaneous abortion rate per 1,000 births during the Omicron wave compared to the pre-Delta and Delta waves. During the Omicron wave, gestational diabetes mellitus was lower compared to the Delta wave and eclampsia (onset of convulsions) was reported to be higher during the Omicron wave,” Dr Gajbhiye said.
Overall, there was a reduction in the severity of disease and maternal mortality during the Omicron wave than during the pre-Delta and Delta waves in the Mumbai metropolitan region. Similar observations are also reported from the US, South Korea, the researchers said. The increase in the number of symptomatic Covid cases could be down to immune evasion, they explained.
The decrease in severity may be explained by the fact that Omicron infection was mainly limited to the upper respiratory tract. However, more data is required to better understand the factors responsible for higher symptomatic cases and the decline in disease severity during the Omicron wave, according to Dr Geetanjali Sachdeva, director of the ICMR-NIRRCH and a co-author of the study.
“We do not have any control over the nature of the next SARS-CoV-2 variant, but pregnant and lactating women do have control over receiving Covid-19 vaccine and protecting themselves and their babies. Covid-19 vaccination has been proven to help prevent severe illness and reduce mortality and pregnancy complications. Pregnant and lactating women in India have been eligible for Covid-19 vaccination since July 2021 and they must be counselled to get the vaccines,” Dr Smita Mahale, a former director of the ICMR-NIRRCH and co-author, said.