MMWR News Synopsis for February 15, 2019
Update: Influenza Activity — United States, September 30, 2018–February 2, 2019
Influenza activity in the United States remained elevated through February 2, 2019, and is expected to continue for several more weeks. 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. Since December 2018, influenza activity increased overall and remained elevated through early February. Nationwide, influenza A(H1N1)pdm09 viruses have predominated, but in the southeastern United States influenza A(H3N2) viruses have predominated. As of February 2, 2019, this has been a low-severity influenza season, with a lower percentage of outpatient visits for influenza-like illness (ILI), lower rates of hospitalization, and fewer deaths attributed to pneumonia and influenza compared with recent seasons. Nevertheless, this season has resulted in many illnesses, hospitalizations and deaths, which are being reported in-season for the first time. The majority of the influenza viruses characterized antigenically and genetically are similar to the cell-grown reference viruses representing the 2018–19 Northern Hemisphere influenza vaccine viruses.
Interim Estimates of 2018–19 Seasonal Influenza Vaccine Effectiveness — United States, February 2019
While flu vaccines vary in how well they work, vaccination can provide important protection against influenza. People age 6 months and older who have not yet been vaccinated this season should be vaccinated. People who are at high risk of serious flu complications and develop flu symptoms, and people who are very sick with flu should be treated early with antiviral medications. CDC recommends yearly influenza vaccination for children at least 6 months old and adults. Early estimates indicate that influenza vaccines have reduced the risk of medically attended influenza-related illness by almost half (47%) in vaccinated people so far this season. Vaccination reduced the rate of illness caused by the predominant influenza H1N1 virus by about 46 percent among patients of all ages, and by about 62 percent among children 6 months through 17 years of age. Vaccination provided similar protection to that seen in previous H1N1 seasons in children and in adults younger than age 50. For these estimates, 3,254 children and adults with acute respiratory illness were enrolled from November 23, 2018 to February 2, 2019 at five study sites with outpatient medical facilities in the United States.
Recommendations of the Advisory Committee on Immunization Practices for Use of Hepatitis A Vaccine for Persons Experiencing Homelessness
The Advisory Committee on Immunization Practices now recommends routine hepatitis A (HepA) vaccination for all people ages 1 year and older who experience homelessness. In October 2018, the Advisory Committee on Immunization Practices (ACIP) unanimously approved updating the recommendations for HepA vaccine to include all people ages 1 year and older experiencing homelessness. The new recommendation is based on evidence showing the substantial public health and cost benefit of routine HepA vaccination for people who are homeless. Additionally, recent outbreaks of hepatitis A virus transmission have demonstrated the vulnerability of this population to this infection. Between 2016 and 2018, more than 7,000 cases of hepatitis A infection were reported in 12 states. The majority of these infections were among people reporting homelessness and/or injection or non-injection drug use. HepA vaccination for people who are homeless will protect these vulnerable individuals and reduce the risk of person-to-person outbreaks among this population.