Flu is making people miserable from coast to coast, thanks in large part to a new strain called subclade K.
That’s why infectious disease experts are telling people to run, not walk, to get this season’s flu shot if they haven’t yet.
But you may be wondering whether getting a flu vaccine will still help or even if getting the vaccine might be riskier than getting sick. It can help, and the flu is far riskier — but misinformation about vaccines is almost as rampant as the germs they protect against, and it can be hard to know what to believe.
Here are some of the most common myths about flu vaccines and what the science shows.
Myth: The flu shot doesn’t work.
The reality is that people who get a flu shot are less likely to become severely ill, be hospitalized or die.
In a social media post Tuesday, Jim O’Neill, acting director of the US Centers for Disease Control and Prevention, said that a review by the US Department of Health and Human Services “found no randomized controlled trials demonstrating reduction of community transmission, hospitalizations, or mortality in children from the pediatric [flu] vaccine.”
He’s right, says Dr. Mark Loeb, a flu researcher at McMaster University in Ontario – but that’s because randomized controlled trials aren’t the right tool for measuring severe outcomes of the flu.
“For randomized controlled trials, most of them are underpowered to detect outcomes like even hospitalizations or deaths,” Loeb said, meaning they don’t have enough people in them to accurately detect differences in these outcomes, which are less common than infections.
Loeb published a meta-analysis, or study of studies, in October in the journal Clinical Microbiology and Infection that included 165 observational studies with “test-negative designs,” which look at all the people who are treated for the same set of symptoms in an emergency room or clinic and then compare the vaccination status of those who tested positive for the flu against those who tested negative.
If a vaccine is effective, there will be fewer vaccinated people in the group that tests positive for the flu compared with those with the same symptoms who tested negative.
Test-negative studies are powerful because they eliminate an important type of bias in observational studies: that people who go to the doctor may be generally more concerned about their health and more likely to get vaccinated than those who don’t go to the doctor.
Together, the studies included more than 600,000 participants. They found that vaccines provide protection against severe flu complications at any age and regardless of how well the shots match the circulating flu strains.
The analysis found that, on average, flu vaccines cut the risk of hospitalization or intensive care admission for children by about half and the risk of pneumonia by 70%. For adults up to 65, vaccination reduced the odds of hospitalization or pneumonia by 40%. Those over 65 saw a roughly 30% reduction in the risk of hospitalization, a 45% reduction in the risk of pneumonia and a 53% drop in the odds of needing intensive care.
“I think it is particularly important year for people to get a flu shot, given the increased severity of the [virus] that’s circulating, and our paper provides good proof for this,” Loeb said.
Myth: There’s no point in getting a flu vaccine since it doesn’t match the new strain, subclade K.
The reality is that the current vaccine is still offering important protection.
It’s true that there’s a new flu virus going around and that it’s not included in this year’s shots. But that doesn’t seem to be affecting how well the vaccines work as much as scientists first feared it might.
Subclade K is an A-type flu strain, specifically an H3N2 virus.
H3N2 strains change quickly and often bedevil the best efforts of scientists to choose strains to include in each year’s vaccines.
That happened this year. After the three strains for this year’s shots were chosen, H3N2 began circulating in the Southern Hemisphere, driving a record flu season in Australia.
One big question has been how well this season’s flu shots protect against this new strain. Years when an H3N2 virus is the main driver of infections tend to have more severe disease, making answers about vaccine effectiveness even more urgent.
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