COVID-19 Vaccine and Pregnancy: Are Infants Protected via Maternal Vaccination?

Infants aged younger than 6 months are at an increased risk of developing severe COVID-19 disease; however, this population is not eligible for vaccination against COVID-19. Prevention in this population, therefore, should focus on maternal vaccination, according to study results published in MMWR Morbidity and Mortality Weekly Report.

Researchers analyzed COVID-19-Associated Hospitalization Surveillance Network (COVID-NET) data to describe hospitalization rates, maternal vaccination status (receipt of COVID-19 vaccination at any point during pregnancy), clinical outcomes, and codetections of other viruses among infants aged younger than 6 months who were hospitalized with laboratory-confirmed COVID-19 across 2 respiratory virus seasons (October 2022-September 2023 and October 2023-April 2024). Laboratory-confirmed COVID-19-associated hospitalization was defined as a positive SARS-CoV-2 test result during hospitalization or within the 14 days preceding hospital admission. Age-stratified hospitalization rates were calculated using demographic data collected in 90 counties across 12 states in the US. Wilcoxon rank-sum and Fisher exact chi-square tests were used in statistical analysis.

A total of 1470 COVID-19-associated hospitalizations among 1148 infants (median age at hospital admission, 64 days; boys, 59.4%; White, 34.6%; no underlying conditions, 76.0%) were identified.

Weekly COVID-19 hospitalization rates were highest among infants aged younger than 6 months vs other pediatric age groups during the weeks that ended on December 17 in 2022 to 2023 (23.0 per 100,000 infants) and January 13 in 2023 to 2024 (20.3 per 100,000 infants).

Cumulative hospitalization rates in infants were lower between October 2023 and April 2024 vs October 2022 and April 2023 (rate ratio [RR], 0.77; 95% CI, 0.69-0.86).

In 2023 to 2024, hospitalization rates were higher only among adults aged 75 and older vs young infants (RR, 0.34; 95% CI, 0.31-0.37). Hospitalization rates among infants and adults aged 65 to 74 were comparable (RR, 1.1; 95% CI, 1.0-1.2).

Maternal vaccination data were available for 1065 (92.6%) infants. The mothers of 921 (87.5%) infants had no documentation of COVID-19 vaccination during pregnancy. Between the 2022 to 2023 and 2023 to 2024 seasons, the percentage of hospitalized infants whose mothers were vaccinated decreased from 17.6% to 4.3% (P <.001). All infants who died in-hospital were born to mothers with no record of vaccination during pregnancy.

A total of 260 (22.1%) infants were admitted to the intensive care unit (ICU), 9 (0.8%) infants died in the hospital, and 56 (4.8%) received mechanical ventilation.

At least 1 underlying condition was noted in 24% of infants, the most common of which were prematurity (17.1%), cardiovascular disease (6.6%), chronic lung disease (4.7%), and neurologic disorders (3.3%).

Study limitations include potential misclassification, unavailable population estimates for infants aged younger than 6 months, reliance on clinician-driven testing, and reduced generalizability of results to the entire United States population.

“[P]revention should focus on ensuring that pregnant persons receive recommended COVID-19 vaccines, as well as follow recommendations such as hand hygiene for COVID-19 prevention and newborn care,” the researchers concluded.

This article originally appeared on Infectious Disease Advisor