Influenza Vaccine Effectiveness in Preventing Influenza-associated Hospitalizations During Pregnancy: A Multi-country Retrospective Test Negative Design Study, 2010–2016

In this retrospective cohort of over 2 million pregnancies that researchers assembled from 2010 to 2016 across 5 regions in 4 countries, 84% of the pregnancies overlapped with an influenza season. Thus, the risk of influenza virus infection is relevant to most pregnant women.