COCA Now: Update - MMWR Update Summary

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Update: Influenza Activity in the United States During the 2017–18 Season and Composition of the 2018–19 Influenza Vaccine


The severity and duration of the 2017-2018 influenza season underscores the tremendous burden seasonal flu can cause and the importance of influenza countermeasures including influenza vaccination and antiviral treatment. While flu vaccination can vary in how well it works, effectiveness in the range of 20 percent to 50 percent may still prevent tens of thousands of hospitalizations during seasons with high severity. Also, flu vaccination has been shown to be life saving for children. Prompt treatment with influenza antiviral medications can shorten duration and severity of symptoms and prevent serious flu complications.

While CDC and partners are working to improve existing flu countermeasures, increases in flu vaccine uptake and the appropriate use of antiviral drugs for treatment could further reduce the burden of influenza in the United States. Influenza activity in the United States during the 2017-18 season began increasing in November followed by an extended period of high activity nationally during January and February and remained elevated through March. Influenza A(H3N2) viruses were most common through February and predominated overall but influenza B viruses, especially B/Yamagata lineage, were most common from March through May. This was a high-severity season: severity indicators (e.g., hospitalization, mortality rates) were higher than what has been observed during previous influenza A(H3N2) predominant seasons.

Studies are underway to better understand the reasons for this high severity. In addition, a high number of influenza-associated pediatric deaths were reported this season.

Read the full MMWR report here.

Update: Recommendations for the Use of Quadrivalent Live Attenuated Influenza Vaccine (LAIV4) — United States, 2018–19 Influenza Season

On February 21, 2018, ACIP recommended that intranasally administered live attenuated influenza vaccine (LAIV4) be an option for influenza vaccination of people for whom it is appropriate for the 2018–19 season. This article provides an overview of the information discussed in the decision-making process leading to this recommendation. Intranasally administered LAIV was initially licensed in the United States in 2003 as a trivalent formulation (LAIV3; FluMist, MedImmune, LLC). Quadrivalent live attenuated influenza vaccine (LAIV4; FluMist Quadrivalent, MedImmune) has been licensed in the United States since 2012 and was first available during the 2013–14 influenza season, replacing LAIV3. During the 2016–17 and 2017–18 influenza seasons, the Advisory Committee on Immunization Practices (ACIP) had recommended that LAIV4 not be used because of concerns about low effectiveness against influenza A(H1N1)pdm09-like viruses circulating in the United States during the 2013–14 and 2015–16 seasons. A description of methodology and data reviewed for the decision will be included in the background materials that will supplement the 2018–19 ACIP Influenza Recommendations, which will replace the 2017–18 ACIP influenza statement, and which will also contain guidance for the use of LAIV4.

Read the full MMWR report here.