Estimated cumulative incidence of pandemic (H1N1) influenza among pregnant women during the first wave of the 2009 pandemic

Perinatal outcomes and congenital abnormalities in the newborns of women affected by the 2009 pandemic influenza A (H1N1) in Beijing, China

“…A study conducted in Beijing in the pre-pandemic period suggested that the prevalence of pre-existing cross-reactive antibodies against the H1N1pdm virus was 1.6% among 310 nonpregnant women of reproductive age (20-45 years old) (unpublished data). This rate was lower than the 4% and 7% reported for Western Australia [15] and Canada [16], respectively, which may be related to seasonal influenza vaccination [17]. In the present study, of 136 serum samples collected after the high pandemic wave, 23 (16.9%) were positive.…”

“…This high rate indicates that a majority of the women in group 2 may have been infected because none had been vaccinated. Considering that a higher prevalence of pre-existing antibodies may be observed in older pregnant women [16], women testing positive and women testing negative were compared within 2 age groups to control for the confounding factor of age. However, the inclusion of age subgroups may have reduced the statistical power of the study.…”

Seroprevalence of Pandemic H1n1 Influenza Among Pregnant Women in Kerala, India

“…44% of the participants were in their second trimester of pregnancy. In contrast to 10 to 20% prevalence in other studies conducted in India and other countries, 15,16 very high proportion (98.6%) of pregnant women were sero-converted during the pandemic in Kerala.…”

Patterns of spread of influenza A in Canada

“…[28][29][30][31]). We define the basic reproduction number R 0 ¼ kbðtÞl=g [32], where the expectation is taken over the time window that we model.…”