United States: This year’s seasonal flu vaccine was found to be less effective in South America than the previous season, according to the CDC report released Thursday, which may provide an indication of how well the shots will work in protecting Americans this winter.
More about the news
Its efficacy stood at 34.5 percent against hospitalization, per interim findings from a new Morbidity and Mortality Weekly Report or MMWR article from the CDC, among high-risk populations, including the young, persons with comorbidities, and the elderly.
What that means is that vaccinated individuals in those categories were 34.5 percent less likely than a non-vaccinated person to become ill enough to require a hospital stay, CBS News reported.
Vaccine effectiveness as per experts
Last year, based on the CDC report suggested that vaccination efficacy in South America may stand at 51.9 percent against the development of hospitalization among high-risk categories.
In a study conducted by the same group that analyzed the data between the years 2013 and 2017, the estimated efficacy was 43 percent for recipients of the full regimen for children of a young age and 41 percent for the elderly.
These data were obtained from a survey research network undertaken under the auspices of the Pan-American Health Organization and involving Argentina, Brazil, Chile, Paraguay, and Uruguay.
What more are the experts stating?
The one that could have declined the most this year may be ‘A(H1N1)pdm09’, the strain circulating since the H1N1swine flu that broke out in 2009.
In the past, flu vaccines have often provided a higher immune response against H1N1 than H3N2 or displayed better human immunity against H1N1 than H3N2.
While the H1N1 virus dominated almost all the infections throughout the last year in South America, this year, according to the World Health Organization, more detections of the H3N2 subtype of flu have been made.
According to the study’s author, if the northern hemisphere is seen to encounter similar patterns of flu virus strains, “health authorities might anticipate similar levels of protection.”
Moreover, as a CDC spokesperson stated, the vaccine’s effectiveness for H1N1 was “within the range” of previous seasons.
According to David Daigle, the CDC spokesperson, “Overall, flu vaccination reduced the risk of hospitalization by about one-third, which would have a significant impact on disease burden. Receiving a flu vaccine can offer significant protection against severe outcomes,” CBS News reported.