Spatio-temporal patterns of influenza A and B across the United States and the influenza vaccine effectiveness in 2011-2018

Abstract

Objective: We aim to study the spatio-temporal patterns of influenza laboratory confirmations, and the possible correlation with the influenza vaccine effectiveness in the Unites States. Methods: We download the state-level influenza laboratory confirmations and the influenza vaccine effectiveness from 2011 to 2018 in the Unites States. We calculate the ratio of weekly influenza B confirmations over influenza A confirmations. It is generally believed that annual influenza A epidemics are more severe than influenza B epidemics and both epidemics occur in the winter and B tends to be delayed. It is unclear how the ratio of B over A changes in the period from 2011-2018. Results: We found that the ratio of weekly Influenza B confirmations over Influenza A confirmations peaked in 2015 and it happened that the influenza VE was particularly low in 2015. Conclusion: The peak in the ratio of Influenza B over Influenza A weekly confirmations in 2015 could be partly due to the low VE in that year in the US. The other reason could be the emergence of a new strain in B/Yamagata lineage in 2014-15.