CDC: This year's flu shot almost 60% effective
ATLANTA - The Centers for Disease Control and Prevention on Thursday reported preliminary overall influenza vaccine effectiveness of 59% this season. 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%,” stated Joseph Bresee, 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 vaccine effectiveness estimates:
51% vaccine effectiveness against the H1N1 viruses responsible for most flu illness this season;
76% vaccine effectiveness against all influenza B viruses; and
79% vaccine effectiveness against the B/Yamagata lineage of B viruses.
At this time, there are not enough data to estimate vaccine effectiveness by age group, nor to estimate vaccine effectiveness against H3N2 viruses or B/Victoria lineage viruses, the CDC reported.
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 Jan. 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 flu 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.
Interim VE estimates are based on data collected from the U.S. Flu VE Network from Nov. 2, 2015, through Feb. 12, 2016. With weeks to go for the current flu season, vaccine effectiveness estimates may change.