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Update on 2017-2018 Influenza Vaccine Effectiveness
MMWR; 2018 Feb 16; Flannery, et al
The overall effectiveness of the 2017-2018 seasonal influenza vaccine is 36%, according to a new Morbidity and Mortality Weekly Report from the Centers for Disease Control and Prevention. Key points include:
- Seasonal effectiveness of the flu vaccine varies season to season and has been higher against A(H1N1)pdm09 and B viruses than against A(H3N2).
- But so far, A(H3N2) has predominated this season, though other viruses have played a role.
- CDC’s data includes >4,500 children and adults with acute respiratory disease from November 2, 2017 to February 3, 2018, including 5 outpatient medical facilities.
Citation:
Flannery B, Chung JR, Belongia EA, et al. Interim estimates of 2017-18 seasonal influenza vaccine effectiveness—United States, February 2018. MMWR. 2018;67(6):180-185. doi:10.15585/mmwr.mm6706a2.
This study confirms that the influenza vaccine for this season (2017-18) has limited overall effectiveness, largely due to low vaccine effectiveness (VE) against the A (H3N2) virus which is the predominant virus this season. However, there is good news in the data too. There were 2 age groups (6 months to 8 years, and 18-49 years) where those who had been vaccinated had statistically significant protection against medically attended influenza (59% and 33% respectively), which is important and meaningful. VE data need to be evaluated carefully as the total VE in the whole population does not necessarily tell the whole story for all vaccine recipients.
—Sarah Rawstron, MB, BS, FAAP, FIDSA
Pediatric Residency Program Director, The Brooklyn Hospital Center, NY
Clinical Associate Professor, Icahn School of Medicine, Mount Sinai, NY