So, finally we have a study that proves once and for all that the flu vaccine doesn’t work! Well, at least not like they try to shove down our throats every single year! In a recent study researchers have found that there are significant gaps in the evidence of their efficacy. Efficacy meaning their usefulness!!
In a meta-analysis, the trivalent inactivated vaccine (TIV) — the most widely prescribed type of vaccine in the U.S. — had a pooled efficacy of 59% in people 18 through 64, according to Michael Osterholm, PhD, of the University of Minnesota in Minneapolis, and colleagues.
But there was no usable data on TIV efficacy in children ages 2 through 17 or adults 65 and older, Osterholm and colleagues reported online in The Lancet Infectious Diseases.
On the other hand, the live attenuated vaccine (LAIV) was highly effective in children ages 6 months to 7 years, but there were no good data for older children or adults, the researchers said.
“While the vaccine does work — and we still recommend that it be used — it does not deliver the levels of efficacy that have often been reported,” Osterholm said in a podcast interview with the journal.
The public, he said, might be under the impression that “this is what we need and this is all we need.” But, “we surely need to develop new and better vaccines to fill these gaps,” he added.
The results of the study will come as no surprise to, “everyone who has been a scholar of influenza and influenza vaccines,” said William Schaffner, MD, of Vanderbilt University in Nashville, and a spokesman for the Infectious Diseases Society of America, who was not involved in the study.
“Most years, it will prevent illness, it will prevent hospitalizations, and it will prevent deaths.” But, he added, “it won’t prevent them all and it cannot eradicate influenza,” as vaccines have done for some other diseases.
In what Osterholm described as the “most exhaustive review to date,” the researchers winnowed through 5,707 articles to come up with 31 studies that met strict criteria for inclusion, including 17 randomized controlled trials and 14 observational studies.
“These are the very best of all the studies that have been done,” he said. Osterholm and colleagues used the randomized trials to generate estimates of efficacy, defined as relative reduction in influenza risk after vaccination.
The observational studies were used to obtain estimates of real-world effectiveness, defined as relative reduction in influenza risk in vaccinated individuals, where medically attended, laboratory-confirmed influenza was the primary outcome.
The researchers found:
- 10 randomized controlled trials showed efficacy in eight of the 12 flu seasons they analyzed. In adults 18 through 64, the pooled efficacy was 59% with a 95% confidence interval from 51% to 67%
- For children 2 through 17 years and adults 65 or older, there were no trials that met inclusion criteria
- 10 trials showed efficacy of LAIV in nine of the 12 analyzed seasons, with a pooled efficacy of 83% (95% CI from 69% to 91%) in children ages 6 months to 7 years
- No LAIV trials met inclusion criteria for children 8 through 17
- For effectiveness, six of 17 analyses in nine studies showed significant protection against medically attended influenza in the outpatient or inpatient setting, ranging from 47% to 72%
- The monovalent pandemic H1N1 vaccine had a median effectiveness of 69% in five observational studies.
The new findings “understandably” have led Osterholm and colleagues to join in calls for better vaccines.
Schaffner said he hopes the study will spur the pharmaceutical industry and governments to put more resources into improving the product.
The bottom line, he told MedPage Today, is that the annual flu vaccine is “a pretty good vaccine, but not a great one.”
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