1904. Lack of efficacy of trivalent influenza vaccination of HIV positive pregnant women against adverse fetal outcomes: A Randomized Clinical Trial
Session: Poster Abstract Session: Vaccines: Influenza
Saturday, October 10, 2015
Room: Poster Hall
Background: It has been shown that antenatal maternal immunization with influenza vaccines has an impact on reducing the incidence of 1) low birth weight (LBW), 2) small size for gestational age (SGA) and 3) prematurity.

Methods: A double-blind, randomized, placebo-controlled Phase II trial of trivalent inactivated influenza vaccine (IIV3) was conducted HIV + pregnant women in Soweto, South Africa. Initiated in March, 2011, it was completed after the 2011 influenza season when the probands had reached 24 weeks of age.  A secondary objective, presented here, was to evaluate the efficacy of IIV3 during pregnancy against fetal outcomes.

Results: Overall, There were 185 infants with known outcomes whose mothers were vaccinated >14 days prior to delivery. There were no miscarriages or stillbirths and no statistically significant differences between incidence rates for any of the 3 outcome measures. Nor were there significant differences between IIV3 and placebo for gestational age (GA) (P = 0.71) or birth weight (BW) as a continuous (P = 0.75) or categorical (P = 0.58) variable. For mothers at risk during an influenza season only, there were 168 known infant outcomes. There were no statistically significant differences between incidence rates for any of the 3 outcome measures nor were there significant differences for mean GA (P = 0.35) or BW as a continuous (P = 0.53) or categorical (P = 0.39) variable. None of the GA-adjusted birth weight analyses reached statistical significance. For mothers with or without an influenza infection prior to delivery (detected by PCR or serology), 170 infants had a known fetal outcome. Infants of the influenza-negative mothers had significantly higher incidence rates of near term births (P = 0.033). None of the other IRRs for fetal outcome approached significance. There were no significant differences for mean GA (P = 0.85) or birth weight as a continuous (P = 0.38) or categorical (P= 0.43) variable. The Influenza-positive group had a higher rate of preterm/AGA-adjusted birth weight compared to the reference groups (IRR = 3.14, 95% CI: 1.05-9.38

Conclusion: There was no evidence of a beneficial effect of IIV3, however there was a potential unexplained effect of seasonal influenza infection during pregnancy on birth weight.

Eric A. F. Simões, MB; BS, DCH, MD1,2,3, Claire Cutland, MD4, Phyllis Carosone-Link, MSPH5, Andrea Hugo, MD2, Stephanie Jones, MD2, Keith Klugman, MD, PhD, FIDSA2, Marta Nunes, PhD2, Shabir Madhi, MD, PhD6 and MatFlu Team, (1)Department of Epidemiology and Center for Global Health, Colorado School of Public Health, Aurora, CO, (2)Respiratory and Meningeal Pathogens Research Unit, Johannesburg, South Africa, (3)Pediatric Infectious Disease, University of Colorado School of Medicine, Aurora, CO, (4)DST/NRF Vaccine Preventable Diseases, University of the Witwatersrand, South Africa, Johannesburg, South Africa, (5)Childrens Hospital Colorado, Aurora, CO, (6)Respiratory and Meningeal Pathogens Research Unit, University of the Witwatersrand, Bertsham, South Africa

Disclosures:

E. A. F. Simões, Bill and Melinda Gates Foundation: Grant Investigator , Research support

C. Cutland, Bill and Melinda Gates Foundation: Grant Investigator , Research support

P. Carosone-Link, Bill and Melinda Gates Foundation: Grant Investigator , Research support

A. Hugo, Bill and Melinda Gates Foundation: Grant Investigator , Research support

S. Jones, Bill and Melinda Gates Foundation: Grant Investigator , Research support

K. Klugman, Bill and Melinda Gates Foundation: Investigator , Research support

M. Nunes, Bill and Melinda Gates Foundation: Grant Investigator , Research support

S. Madhi, Bill and Melinda Gates Foundation: Grant Investigator , Grant recipient and Research support

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