Association between Influenza Vaccination Rates and SARS-CoV-2 Outbreak Infection Rates in OECD Countries

From December 2019 to early March 2020, the local outbreak of novel corona virus disease (COVID-19) in central China’s Hubei region has grown into a worldwide pandemic. This rapid and catastrophic escalation makes the search for and understanding of the underlying mechanisms of infection and disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as well as of their associated risk factors an urgent priority. In particular, strong variations in COVID-19 infection rates as seen internationally require a better understanding. Here we show that reported influenza vaccination coverage rates for 29 OECD countries are associated significantly with recently observed SARS-CoV-2 infection rates in these countries. This early observation, which merits further investigation, suggests that during the current coronavirus outbreak an influenza vaccination background might be a relevant factor for SARS-CoV-2 infection. The observed phenomenon is discussed in the context of vaccine associated virus interference and antibody-dependent enhancement of viral infectivity.