Influenza Activity — United States and Worldwide, May 19–September 28, 2019, and Composition of the 2020 Southern Hemisphere Influenza Vaccine

Scott Epperson, DVM; C. Todd Davis, PhD; Lynnette Brammer, MPH; Anwar Isa Abd Elal; Noreen Ajayi, MPH; John Barnes, PhD; Alicia P. Budd, MPH; Erin Burns, MA; Peter Daly, MPH; Vivien G. Dugan, PhD; Alicia M. Fry, MD; Yunho Jang, PhD; Sara Jo Johnson, MPH; Krista Kniss, MPH; Rebecca Kondor, PhD; Lisa A. Grohskopf, MD; Larisa Gubareva, PhD; Angiezel Merced-Morales, MPH; Wendy Sessions, MPH; James Stevens, PhD; David E. Wentworth, PhD; Xiyan Xu, MD; Daniel Jernigan, MD


Morbidity and Mortality Weekly Report. 2019;68(40):880-884. 

In This Article

Abstract and Introduction


During May 19–September 28, 2019,* low levels of influenza activity were reported in the United States, with cocirculation of influenza A and influenza B viruses. In the Southern Hemisphere seasonal influenza viruses circulated widely, with influenza A(H3) predominating in many regions; however, influenza A(H1N1)pdm09 and influenza B viruses were predominant in some countries. In late September, the World Health Organization (WHO) recommended components for the 2020 Southern Hemisphere influenza vaccine and included an update to the A(H3N2) and B/Victoria-lineage components. Annual influenza vaccination is the best means for preventing influenza illness and its complications, and vaccination before influenza activity increases is optimal. Health care providers should recommend vaccination for all persons aged ≥6 months who do not have contraindications to vaccination.[1]

* Data reported as of October 4, 2019.