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. 2021 Aug 9;39(34):4864-4870.
doi: 10.1016/j.vaccine.2021.06.065. Epub 2021 Jul 12.

Body mass index and vaccine responses following influenza vaccination during pregnancy

Affiliations

Body mass index and vaccine responses following influenza vaccination during pregnancy

Michelle Clarke et al. Vaccine. .

Abstract

Background and aims: Influenza vaccination is recommended by the World Health Organisation for pregnant women, offering the dual benefit of protecting pregnant women and their newborn infants against influenza infection. Various factors can influence vaccine immunogenicity, with obesity being one factor implicated in varied responses. This study aimed to investigate the impact of body mass index (BMI) on vaccine responses following influenza vaccination during pregnancy.

Methods: Pregnant women attending the Women's and Children's Hospital in South Australia during 2014-2016 were invited to participate. Participant's clinical and demographic factors were recorded prior to administration of licensed seasonal influenza vaccination. Blood samples were collected before and one month post-vaccination to measure antibody responses by haemagglutination inhibition (HI) assay. Seroprotection was defined as a post-vaccination HI titre ≥ 1:40. Regression models assessed associations with failure to achieve seroprotective antibodies to H1, H3, and B influenza strains.

Results: A total of 96 women were enrolled in the study at a median gestation of 22 weeks with a BMI range of 18-49 kg/m2. Paired sera samples were available for 90/96 (94%). Most pregnant women (72/90, 80%) demonstrated seroprotective antibody titres to all three influenza vaccine antigens (A(H1N1)pdm09, A(H3N2), B/Yamagata) following vaccination. Compared with women with BMI < 30 kg/m2, those with high BMI were less likely to fail to achieve seroprotective antibodies, however this was not statistically significant (RR 0.42, 95% CI 0.11-1.68; p = 0.22). A greater proportion of women vaccinated during their second (47/53, 93%) or third trimester (18/25, 72%) demonstrated seroprotection to all three vaccine antigens following vaccination compared with women vaccinated during their first trimester (7/12, 58%).

Conclusion: High BMI did not impair seroprotection levels following influenza vaccination in pregnant women. Gestation at vaccination may be an important consideration for optimising vaccine protection for pregnant women and their newborns. Further assessment of first trimester influenza vaccine responses is warranted.

Keywords: Immunogenicity; Influenza; Obesity; Vaccination; Vaccine.

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Conflict of interest statement

Declaration of Competing Interest M Clarke, HS Marshall and S Evans are Investigators on clinical vaccine trials sponsored by Industry. Their institution (Women’s and Children’s Hospital) receives funding for Investigator led research and/or sponsored vaccine trials from Industry, including GSK, Pfizer, Sanofi, Novavax and Merck. None of the authors receive any personal payments from Industry. S Lambert, LC Giles, SG Sullivan and LM Goodchild have no conflicts to declare. IG Barr has shares in an influenza vaccine producing company. The WHO Collaborating Centre for Reference and Research on Influenza receives funds from Seqirus Limited and from the IFPMA for its influenza surveillance activities. The WHO Collaborating Centre for Reference and Research on Influenza is funded by the Australian Government Department of Health. The funding bodies were not involved in the collection, analysis or interpretation of data, the writing of the article, or the decision to submit the article for publication.

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