MMWR News Synopsis for Friday, June 21, 2019
Trends in the Laboratory Detection of Rotavirus Before and After Implementation of Routine Rotavirus Vaccination — United States, 2000–2018
Rotavirus vaccination has dramatically reduced U.S. disease burden and altered seasonal patterns. Improving coverage and on-time rotavirus vaccination of children is critical to maximize public health benefit. Rotavirus, a common cause of gastroenteritis in young children, is preventable with vaccines used in the United States since 2006. CDC analyzed laboratory testing data for rotavirus collected through national surveillance during the pre-vaccine (2000–2006) and post-vaccine (2007–2018) periods. In the post-vaccine period, we observed a decline in annual rotavirus tests; the annual peak in positive tests declined and the rotavirus season was shorter. A biennial rotavirus seasonal pattern emerged with alternating years of low and high disease activity. Rotavirus vaccination has dramatically reduced the disease burden. Peak rotavirus activity declined by more than two thirds, from an annual median of 43.1% in the pre-vaccine era to 14.0% in the post-vaccine era; and peak season was shortened from 26 weeks to 9 weeks. These changes have been sustained over 11 post-vaccine–introduction seasons. To maximize the public health impact, efforts to improve coverage and on-time rotavirus vaccination should continue.
Update: Influenza Activity in the United States During the 2018–19 Season and Composition of the 2019–20 Influenza Vaccine
The 2018–19 influenza season in the United States was of moderate severity and lasted 21 weeks, making it the longest season in 10 years. Influenza vaccination is the best way to reduce the risk of influenza and its potentially serious consequences, including hospitalizations in adults and deaths in children. Influenza antiviral medications are an important adjunct to vaccination in the treatment and prevention of influenza. U.S. influenza-like illness activity began increasing in November 2018, peaked during mid–February, and returned below baseline in mid-April 2019. Influenza A viruses predominated with very little influenza B activity. Two waves of influenza A were notable during this extended season: A(H1N1)pdm09 from October 2018 to mid-February 2019 and A(H3N2) from February through May 2019. Compared to the 2017-18 season, hospitalization rates were lower among adults but higher among children. The majority of A(H1N1)pdm09 and influenza B viruses characterized antigenically and genetically were similar to recommended Northern Hemisphere 2018-2019 cell grown vaccine reference viruses; however, the majority of A(H3N2) viruses were antigenically distinct from the vaccine virus, prompting a change to the 2019-20 Northern Hemisphere A(H3N2) vaccine component to an A/Kansas/14/2017 (H3N2)-like virus.