Impact of Maternal HIV Infection and Placental Malaria on the Transplacental Transfer of Influenza Antibodies in Mother-Infant Pairs in Malawi, 2013 - 2014

Background. Maternal influenza vaccination protects infants against influenza virus infection. Impaired transplacental transfer of influenza antibodies may reduce this protection.

Methods. We conducted a cross-sectional study of influenza vaccine-naïve pregnant women recruited at delivery from Blantyre (urban, low malaria transmission) and Chikwawa (rural, high malaria transmission) in Southern Malawi. HIV-infected mothers were excluded in Chikwawa. Maternal and cord blood antibodies against circulating influenza strains A/California/7/2009, A/Victoria/361/2011, B/Brisbane/60/2008 and B/Wisconsin/1/2010 were measured by hemagglutination inhibition (HAI). We studied the impact of maternal HIV infection and placental malaria on influenza antibody levels in mother-infant pairs in Blantyre and Chikwawa, respectively.

Results. We included 454 mother-infant pairs (Blantyre, n=253; Chikwawa, n=201). HIV-infected mothers and their infants had lower seropositivity (HAI titer >1:40) against influenza A(H1N1)pdm09 (mothers, 24.3 vs. 45.4%, p=0.02; infants 24.3 vs. 50.5%, p=0.003) and A(H3N2) (mothers, 37.8% vs. 63.9%, p=0.003; infants 43.2 vs. 64.8%, p=0.01), whereas placental malaria had inconsistent effect on maternal and infant seropositivity. In multivariable analyses, maternal HIV infection was associated with reduced infant seropositivity (A(H1N1)pdm09 aOR 0.34, 95%CI 0.15-0.79; A(H3N2) aOR 0.43, 95%CI 0.21-0.89). Transplacental transfer was not impaired by maternal HIV or placental malaria.

Discussion. Maternal HIV infection influenced maternal antibody response to influenza A virus infection and therefore antibody levels in newborns, but did not affect transplacental antibody transfer.