Influenza vaccine: nearly 60% effective this season

March 25, 2016  Centers for Disease Control & Prevention

adult vaccine

The Centers for Disease Control and Prevention today reported preliminary overall influenza vaccine effectiveness (VE) of 59 percent this season. These data were presented at a meeting of the agency’s Advisory Committee for Immunization Practices (ACIP) in Atlanta. This finding is comparable to past estimates for seasons when most circulating flu viruses and vaccine viruses have been similar.

“This means that getting a flu vaccine this season reduced the risk of having to go to the doctor because of flu by nearly 60 percent,” said Joseph Bresee, M.D., chief of CDC’s Epidemiology and Prevention Branch. “It’s good news and underscores the importance and the benefit of both annual and ongoing vaccination efforts this season.”

There were sufficient data from the U.S. Flu VE Network to also calculate more specific VE estimates:

  • 51 percent VE against the H1N1 viruses responsible for most flu illness this season
  • 76 percent VE against all influenza B viruses
  • 79 percent VE against the B/Yamagata lineage of B viruses

CDC maintains and monitors several influenza surveillance systems. This season, influenza-like-illness levels and the numbers of influenza-positive laboratory tests became elevated the week ending January 16. Activity now has been elevated for five consecutive weeks. For the past 13 seasons, flu seasons have averaged 13 weeks in length, with a low of one week to a high of 20 weeks.

“Flu activity this season started a bit later and has been lower so far than we’ve seen during the previous three seasons, but activity is still on the upswing and expected to continue for several weeks,” said Bresee. “Flu causes serious illnesses and deaths every year. This season, CDC has received reports of hospitalizations and deaths in young, otherwise healthy people who were infected with influenza A H1N1, but not vaccinated.”

While flu vaccine effectiveness can vary, CDC recommends an annual influenza vaccine as the best way to prevent seasonal flu. CDC also recommends rapid treatment of seriously ill and high risk suspect flu patients with influenza antiviral drugs.