tetano
Editor, Senior Moderator
Vaccine
. 2025 Nov 1:68:127887.
doi: 10.1016/j.vaccine.2025.127887. Online ahead of print. Heterogeneity in seasonal influenza vaccination opportunity and disease risk during pregnancy and in infants <6 months
Sinead E Morris[SUP] 1 [/SUP], Alissa O'Halloran[SUP] 2 [/SUP], Devi Sundaresan[SUP] 3 [/SUP], Fatimah S Dawood[SUP] 4 [/SUP], Sascha Ellington[SUP] 2 [/SUP], Lisa A Grohskopf[SUP] 2 [/SUP], Samantha M Olson[SUP] 2 [/SUP], Rebecca K Borchering[SUP] 2 [/SUP], Catherine H Bozio[SUP] 2 [/SUP], Carrie Reed[SUP] 2 [/SUP], Matthew Biggerstaff[SUP] 5 [/SUP]
Affiliations
Pregnant women and infants <6 months are at increased risk of severe influenza but can receive protection through influenza vaccination administered during pregnancy. Since influenza vaccination and virus transmission are seasonal in the United States, the calendar timing of pregnancy could impact the opportunity for influenza vaccination and risk of influenza for pregnant women and their infants. Using data on laboratory-confirmed influenza-associated hospitalizations from 2005/06 to 2022/23 (excluding the 2009/10 and 2020/21 seasons), we assessed the risk of hospitalization by influenza season timing and by pregnancy start and infant birth months. We then used 2022/23 influenza vaccination coverage data, and the weekly number of influenza positive specimens identified from 2005/06 to 2022/23 (excluding 2009/10 and 2020/21), to quantify how the opportunity for seasonal influenza vaccination and risk of influenza exposure varied with pregnancy and birth timing. We found that pregnancy start and infant birth months with the greatest hospitalization risk varied between seasons. In seasons peaking before the second week in January, the greatest percentage of hospitalizations occurred among pregnancies beginning March-June with births in October-December. In seasons peaking later, the greatest percentage occurred among pregnancies beginning May-August with births in November-January. Opportunities for protection through maternal vaccination also varied between pregnant women and infants who were most at risk for influenza. Most pregnant women at risk of influenza had an opportunity for current season vaccination during or before pregnancy (93-98 % depending on season timing). However, only 17-54 % of infants at risk had an opportunity for current season protection as many were born before most influenza vaccines were administered. Our results highlight heterogeneity in influenza vaccination opportunity and risk of influenza and severe disease among pregnant women and young infants and could inform strategies to increase vaccine-mediated protection in those at greatest risk.
Keywords: Infants; Influenza; Maternal vaccination; Pregnancy.
. 2025 Nov 1:68:127887.
doi: 10.1016/j.vaccine.2025.127887. Online ahead of print. Heterogeneity in seasonal influenza vaccination opportunity and disease risk during pregnancy and in infants <6 months
Sinead E Morris[SUP] 1 [/SUP], Alissa O'Halloran[SUP] 2 [/SUP], Devi Sundaresan[SUP] 3 [/SUP], Fatimah S Dawood[SUP] 4 [/SUP], Sascha Ellington[SUP] 2 [/SUP], Lisa A Grohskopf[SUP] 2 [/SUP], Samantha M Olson[SUP] 2 [/SUP], Rebecca K Borchering[SUP] 2 [/SUP], Catherine H Bozio[SUP] 2 [/SUP], Carrie Reed[SUP] 2 [/SUP], Matthew Biggerstaff[SUP] 5 [/SUP]
Affiliations
- PMID: 41176967
- DOI: 10.1016/j.vaccine.2025.127887
Pregnant women and infants <6 months are at increased risk of severe influenza but can receive protection through influenza vaccination administered during pregnancy. Since influenza vaccination and virus transmission are seasonal in the United States, the calendar timing of pregnancy could impact the opportunity for influenza vaccination and risk of influenza for pregnant women and their infants. Using data on laboratory-confirmed influenza-associated hospitalizations from 2005/06 to 2022/23 (excluding the 2009/10 and 2020/21 seasons), we assessed the risk of hospitalization by influenza season timing and by pregnancy start and infant birth months. We then used 2022/23 influenza vaccination coverage data, and the weekly number of influenza positive specimens identified from 2005/06 to 2022/23 (excluding 2009/10 and 2020/21), to quantify how the opportunity for seasonal influenza vaccination and risk of influenza exposure varied with pregnancy and birth timing. We found that pregnancy start and infant birth months with the greatest hospitalization risk varied between seasons. In seasons peaking before the second week in January, the greatest percentage of hospitalizations occurred among pregnancies beginning March-June with births in October-December. In seasons peaking later, the greatest percentage occurred among pregnancies beginning May-August with births in November-January. Opportunities for protection through maternal vaccination also varied between pregnant women and infants who were most at risk for influenza. Most pregnant women at risk of influenza had an opportunity for current season vaccination during or before pregnancy (93-98 % depending on season timing). However, only 17-54 % of infants at risk had an opportunity for current season protection as many were born before most influenza vaccines were administered. Our results highlight heterogeneity in influenza vaccination opportunity and risk of influenza and severe disease among pregnant women and young infants and could inform strategies to increase vaccine-mediated protection in those at greatest risk.
Keywords: Infants; Influenza; Maternal vaccination; Pregnancy.