Are twindemics occurring?

The emergence and spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), prompted worldwide COVID-19 surveillance. To investigate the impact of COVID-19 on influenza activity, we used global surveillance data collected since 2019 to compare the number of cases positive for COVID-19 and for influenza across 22 representative countries (Australia, Brazil, Canada, China, Egypt, France, Germany, India, Israel, Italy, Japan, Mexico, The Netherlands, The Philippines, Poland, The Republic of Korea, South Africa, Spain, Thailand, The United Kingdom, The United States, and Vietnam). Our results demonstrate alternating prevalence of SARS-CoV-2 and influenza virus.