CDC experts emphasized the need for COVID vaccination during pregnancy, showing that children under 6 months are vulnerable to severe disease from infection, as are their mothers — and vaccination can mitigate that.
In its discussions for the upcoming 2025-2026 respiratory virus season, the COVID vaccination workgroup of the Advisory Committee on Immunization Practices (ACIP) considered recommendations that all children 6 to 23 months and people ages 2-64 years at high risk of severe COVID be vaccinated — including pregnant women.
The purpose would be for protection of both the mother and infant, Adam MacNeil, PhD, MPH, of the CDC’s National Center for Immunization and Respiratory Diseases (NCIRD), said during a presentation at the ACIP meeting on Wednesday.
Last month, HHS Secretary Robert F. Kennedy Jr. ended the CDC’s recommendation to vaccinate kids and pregnant women against COVID.
In presenting on COVID epidemiology, MacNeil showed that hospitalization rates in the 2024-25 season were highest among adults age 75 and up, followed by adults ages 65-74 and children under 6 months, who had similar hospitalization rates.
Indeed, cumulative rates of COVID-associated hospitalizations were 268 per 100,000 in kids under 6 months — nearly the same as those for people ages 65-74, at 266 per 100,000, MacNeil reported.
COVID infection can be severe among children under 6 months, with 22% being admitted to the intensive care unit, and the majority (71%) having no underlying medical conditions, he reported. Only 3.5% of these youngest kids who were hospitalized had any record of maternal COVID vaccination during pregnancy.
Since no COVID shots are approved for kids under 6 months, “any protection must come from transfer of maternal antibodies, either from vaccination during pregnancy or prior infection,” MacNeil said.
He cited data from the 2022-23 season showing that maternal vaccination had 54% effectiveness against hospitalization among infants ages 0-2 months. That fell to 35% for ages 0-5 months, but he noted that’s not different from adult data showing that vaccine protection wanes over time.
Vaccination during pregnancy would help mothers, too, as data from COVID-NET from April 2024-March 2025 showed that 28.5% of women ages 15-49 hospitalized with COVID were pregnant. Half of these mothers (50%) had no underlying conditions; 92% had no record of vaccination since July 1, 2023, and only 5.8% received the recommended 2024-25 COVID vaccine dose, he reported.
MacNeil also reported COVID vaccine efficacy data from the 2024-25 season, with 36% effectiveness against emergency department and urgent care visits 7-59 days after vaccination, dropping to 28% at 120-179 days post-vaccination.
For people ages 18-64, vaccine effectiveness against emergency visits ranged from 20% up to 39%, and for ages 65 and up, it ranged from 30%-36%, depending on time since last dose.
Vaccine effectiveness against hospitalization in adults age 65 and up ranged from 50% for 60-119 days post-vaccination to 32% for 120-179 days, according to data from the VISION network. Findings were similar in the IVY network, ranging from 53% for 60-119 days post-vaccination to 40% at 120-179 days, MacNeil reported.
As for kids, VISION data from 2024-25 showed a vaccine effectiveness of 64% for kids ages 9 months to 4 years, and 81% for those ages 5-17 years, all for the timeframe of 7-179 days post-vaccination.
MacNeil noted that vaccine effectiveness should be interpreted as the added benefit of COVID vaccination in a population with high levels of infection- or vaccine-induced immunity, or both.
New ACIP chair Martin Kulldorff, PhD, questioned how the data compared to vaccine effectiveness seen in randomized controlled trials, and FDA ex-officio member Tracy Beth Hoeg, MD, PhD, also called for randomized clinical trials of vaccine effectiveness “to minimize these types of bias so we aren’t sitting here, wondering, are we being misled by these data?”
ACIP panelist Cody Meissner, MD, also raised concerns about people being included whether or not they were hospitalized “for” or “with” COVID, but a CDC subject matter expert explained that for most of the patients included, COVID was identified “as the likely reason for admission for those hospitalizations.”
Meissner also said severe COVID illness appeared to be “rare” among kids, even those under 6 months, but MacNeil noted that the cumulative number of hospitalizations “remains a substantial burden” among the youngest and oldest age groups.
