Search

• The World Health Organization prioritizes influenza vaccination for pregnant individuals. • Multi-country, multi-season influenza vaccine coverage assessments are sparce. • We examined influenza vaccine coverage among pregnant individuals in four countries over ten influenza seasons. Many countries recommend influenza vaccination during pregnancy. Despite this recommendation, influenza vaccine among pregnant individuals remains under-utilized and uptake varies by country. Factors associated with influenza vaccine uptake during pregnancy may also vary across countries. As members of the Pregnancy Influenza Vaccine Effectiveness Network (PREVENT), five sites from four countries (Australia, Canada, Israel, and the United States) retrospectively identified cohorts of individuals aged 18–50 years who were pregnant during pre-defined influenza seasons. Influenza vaccine coverage estimates were calculated for the 2010–11 through 2015–16 northern hemisphere and the 2012 through 2015 southern hemisphere influenza seasons, by site. Sites used electronic health records, administrative data, and immunization registries to collect information on pregnancy, health history, demographics, and vaccination status. Each season, vaccination coverage was calculated as the percentage of individuals who received influenza vaccine among the individuals in the cohort that season. Characteristics were compared between those vaccinated and unvaccinated, by site. More than two million pregnancies were identified over the study period. Influenza vaccination coverage ranged from 5% to 58% across sites and seasons. Coverage increased consistently over the study period at three of the five sites (Western Australia, Alberta, and Israel), and was highest in all seasons at the United States study site (39–58%). Associations with vaccination varied by country and across seasons; where available, parity >0, presence of a high-risk medical condition, and urban residence were consistently associated with increased likelihood of vaccination. Though increasing, uptake of influenza vaccine among pregnant individuals remains lower than recommended. Coverage varied substantially by country, suggesting an ongoing need for targeted strategies to improve influenza vaccine uptake in this population. [ABSTRACT FROM AUTHOR]

Objectives: Findings during the 2009 pandemic suggest severe maternal infection with pandemic influenza had adverse perinatal health consequences. Limited data exist evaluating the perinatal health effects of severe seasonal influenza and non-influenza infections during pregnancy., Methods: A retrospective cohort of pregnant women from Australia, Canada, Israel, and the United States was established using birth records to identify pregnancies and birth outcomes and hospital and laboratory testing records to identify influenza and non-influenza associated acute respiratory or febrile illness (ARFI) hospitalizations. ARFI hospitalized women were matched to non-hospitalized women (1:4) by country and season of conception. Log-binomial regression was used to estimate the relative risk (aRR) of preterm birth (PTB), small-for-gestational-age (SGA), and low birthweight (LBW) birth, adjusting for pre-existing medical conditions, maternal age, and parity., Results: 950 pregnant women hospitalized with an ARFI were matched with 3,800 non-hospitalized pregnant women. Compared to non-hospitalized women, risk of PTB was greater among women hospitalized with influenza-associated ARFI (aRR: 1.57; 95% CI: 1.15-2.15) and non-influenza ARFI (aRR: 2.78; 95% CI: 2.12-3.65). Similar results were observed for LBW; there were no associations with SGA birth., Conclusions: ARFI hospitalization during pregnancy was associated with increased risk of PTB and LBW., Competing Interests: Declaration of Competing Interest ALN reports grants from Pfizer, grants from MedImmune/Astra Zeneca, and grants from Merck unrelated to the submitted work. All other co-authors have no potential conflicts of interest to disclose. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the CDC or the US government. Parts of this manuscript are based on data and/or information compiled and provided by the Canadian Institute for Health Information (CIHI). However, the analyses, conclusions, opinions, and statement expressed herein are those of the authors and not necessarily those of CIHI. No endorsement by ICES, Public Health Ontario, Ontario Ministry of Health and Long-Term Care, or CIHI is intended or should be inferred., (Copyright © 2020. Published by Elsevier Ltd.)