Wrapping Up the 2017-18 Flu Season and Looking Ahead to Prevent Flu in 2018-19

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Wrapping Up the 2017-18 Flu Season and Looking Ahead to Prevent Flu in 2018-19

Stefanie Cole, BSN, RN, MPH, Immunization Nurse Educator, Michigan Department of Health and Human Services Division of Immunization

The 2017-18 influenza season (defined as October 1, 2017–May 19, 2018) was a high severity season for all age groups in the United States. Levels of flu activity are measured using multiple surveillance systems including laboratory data, outpatient visits due to influenza-like illness (ILI), hospitalizations, and deaths. The U.S. experienced high levels of outpatient clinic and emergency department visits due to ILI, high flu-related hospitalization rates, and widespread flu activity across the country for an extended period in 2017-18. Nationally, ILI began to increase in November 2017, peaked at the end of January/beginning of February 2018, and did not return to baseline levels until early April. Overall, 2017-18 was an influenza A(H3N2)-predominant season, although influenza B viruses predominated from March onward (Garten, Blanton, Elal, et al., 2018).

Unfortunately, the 2017-18 flu season saw a record number of influenza-associated pediatric deaths. As of June 1, 2018, 171 flu-associated pediatric deaths were confirmed nationally. The ages of these children ranged from 8 weeks to 17 years with an average age of 7 years. For those children whose medical history was known (n=154), 51% had at least one underlying medical condition that put them at higher risk for flu complications. The other half were previously healthy kids. Among the 138 children who were at least 6 months of age and for whom vaccination status was reported, only 22% received at least one dose of 2017-18 flu vaccine before becoming ill (Garten, Blanton, Elal, et al., 2018).

Further, as of July 14, 2018, the number of flu-associated pediatric deaths nationally increased to 178, two of which were Michigan children (Centers for Disease Control, 2018b; Michigan Department of Health and Human Services, n.d.). Since influenza pediatric deaths became a reportable condition in 2004, the only other flu season with more pediatric flu deaths than this past season was the 2009 pandemic (Garten, Blanton, Elal, et al., 2018). The 2017-18 season underscored the importance of ensuring children are vaccinated against influenza, regardless of if they have underlying medical conditions. Some children will need two doses of flu vaccine during the upcoming flu season. To find out which children need two doses, visit the Michigan Department of Health and Human Services Flu Website and click on the “Current Flu Season Vaccination Materials for Health Care Professionals” to find this and other flu vaccine educational resources.

Estimates from November 2017 found that only about two in every five children and adults in the U.S. had received flu vaccine. About 65% of children who had received flu vaccine by November got it at a doctor’s office. For adults, about 35% got flu vaccine at a doctor’s office and 28% were vaccinated in a pharmacy or store. Because infants younger than 6 months are too young to be vaccinated against flu, vaccinating pregnant women is an important strategy to protect them. Unfortunately, as of November 2017, flu vaccination coverage among pregnant women before and during pregnancy was only 35.6%. All end-season flu vaccine coverage estimates for 2017-18, including Michigan-specific estimates, will be published in September 2018 (Centers for Disease Control, 2017).

The Northern Hemisphere’s 2018-19 flu vaccine composition includes an A/Michigan/45/2015 A(H1N1)pdm09-like virus, an A/Singapore/INFIMH-16–0019/2016 A(H3N2)-like virus, and a B/Colorado/06/2017-like (B/Victoria lineage) virus. Quadrivalent vaccines include these three strains plus a B/Phuket/3073/2013-like (B/Yamagata lineage) virus (Garten, Blanton, Elal, et al., 2018). In June 2018, the Advisory Committee on Immunization Practices (ACIP) voted to continue the universal flu vaccine recommendation for all persons aged 6 months and older for the 2018-19 season (Centers for Disease Control, 2018a). ACIP does not recommend any flu vaccine over another, but recommends that any age-appropriate, licensed flu vaccine may be used. After two years off the market, live, attenuated influenza vaccine (LAIV4, FluMist®) was recommended by ACIP in February 2018 as an option for flu vaccination of persons for whom it is appropriate for the 2018–19 season (Grohskopf, Sokolow, Fry, Walter, & Jernigan, 2018). The complete 2018-19 flu vaccine recommendations can be found at www.cdc.gov/mmwr.

Begin vaccinating all persons aged 6 months and older as soon as flu vaccine is available. Vaccinate not only to protect patients but also anyone they may encounter, including infants who may be too young to receive flu vaccine themselves.


Centers for Disease Control and Prevention (2017). FluVaxView, 2017-18 Flu Season: https://www.cdc.gov/flu/fluvaxview/1718season.htm

Centers for Disease Control and Prevention (2018a). Advisory Committee on Immunization Practices (ACIP): https://www.cdc.gov/vaccines/acip/meetings/meetings-info.html

Centers for Disease Control and Prevention (2018b). Weekly U.S. Influenza Surveillance Report: https://www.cdc.gov/flu/weekly/

Garten, R., Blanton, L., Elal, A.I., et al. (2018) Update: Influenza Activity in the United States During the 2017–18 Season and Composition of the 2018–19 Influenza Vaccine. MMWR Morb Mortal Wkly Rep. 67(22) 634–642. http://dx.doi.org/10.15585/mmwr.mm6722a4

Grohskopf, L.A., Sokolow, L.Z., Fry, A.M., Walter, E.B., Jernigan, D.B.(2018). Update: ACIP Recommendations for the Use of Quadrivalent Live Attenuated Influenza Vaccine (LAIV4) — United States, 2018–19 Influenza Season. MMWR Morb Mortal Wkly Rep 67(22):643–645.  http://dx.doi.org/10.15585/mmwr.mm6722a5