Flu is spreading across the country, leaving many feeling unwell, mainly due to a new strain known as subclade K. Infectious disease experts are urging everyone to get vaccinated if they haven’t already.
You might be questioning whether the flu vaccine is effective or even if it might pose more risks than the illness itself. Well, getting vaccinated is beneficial; the flu certainly poses greater dangers. Yet, misinformation about vaccines abounds, making it challenging to sift through facts.
Let’s explore some common misconceptions surrounding flu vaccines and clarify the science behind them.
People who receive a flu shot are significantly less likely to suffer severe illness, be hospitalized, or die.
In a recent social media update, Jim O’Neill, acting director of the CDC, noted that a review from the Department of Health and Human Services showed no randomized controlled trials proving that the pediatric flu vaccine reduces community transmission, hospitalizations, or mortality in children.
Dr. Mark Loeb, a flu researcher, agrees—though he adds that randomized trials aren’t the best way to assess severe flu outcomes.
“Most trials lack sufficient participants to detect outcomes like hospitalizations or deaths,” Loeb explained. These severe outcomes are less common than cases of infection.
Loeb conducted a meta-analysis examining 165 observational studies to understand vaccine efficacy better, distinguishing between those who tested positive for the flu and those who did not.
If the vaccine is effective, fewer vaccinated individuals will be found among those testing positive.
Such studies are valuable as they eliminate biases seen in observational studies; patients visiting doctors may be generally healthier and more inclined to get vaccinated than those who don’t seek medical help.
Collectively, the studies involved over 600,000 participants, concluding that vaccines protect against severe flu complications for all ages, irrespective of the alignment with circulating strains.
The analysis indicated vaccinations halved the risk of hospitalization or intensive care admissions for children and reduced pneumonia risk by 70%. For adults under 65, hospitalization or pneumonia risks dropped by 40%, while adults over 65 saw reductions of approximately 30% in hospitalization risk, 45% in pneumonia risk, and 53% in the odds of needing intensive care.
I believe this year is particularly crucial for vaccinations, especially given the heightened severity of the circulating virus, and our analysis supports this point,” Loeb said.
Current vaccines still provide essential protection.
It’s true that a new flu strain is making its rounds, and it isn’t included in this year’s vaccines, but that doesn’t seem to significantly impact the current vaccines’ effectiveness as initially feared.
Subclade K is an H3N2 flu strain, and these strains evolve rapidly, often complicating vaccine formulation decisions.
This season saw disruptions when H3N2 emerged in the Southern Hemisphere, triggering a record flu season in Australia.
Questions about how well this season’s vaccines will protect against subclade K have arisen. Years dominated by H3N2 viruses often lead to more severe illnesses, making it critical to assess vaccine effectiveness.
Evidence has been mixed. WHO scientists indicated that blood samples from ferrets vaccinated with the current vaccine didn’t neutralize subclade K very well.
However, the UK’s Health Security Agency, after analyzing around 8,000 ER visits and hospitalizations, found that this year’s flu shots were surprisingly effective. Vaccinations reduced emergency department visits by about 75% for children and 30% to 40% for adults.
Meanwhile, researchers at the University of Pennsylvania’s Perelman School of Medicine have provided more insights. In a preprint study, they took blood samples from 76 adults a month post-vaccination to assess the antibodies’ effectiveness against various flu strains.
“We were quite surprised to find that many individuals produced significant amounts of antibodies that could effectively neutralize subclade K viruses,” said study author Dr. Scott Hensley, whose team worked rigorously during the holiday break to complete their research.
Initially, only 11% of study participants had neutralizing antibodies; post-vaccination, that number rose to 39%.
“The results clearly indicate that even in years with mismatched strains, the vaccine still provides protection,” Hensley emphasized.
Who develops antibodies against subclade K can depend on previous virus exposure, making it hard to predict individual outcomes.
“It’s not perfect, but a fourfold reduction in flu chances is worth a shot,” Hensley commented.
Some may experience mild reactions post-vaccination, but they aren’t severe or related to flu itself.
Research indicates that about one in three people may feel under the weather for a day or two after receiving a flu shot. Common reactions include headaches and fatigue, often closely mimicking flu symptoms. However, they aren’t caused by the flu itself.
Dr. William Schaffner notes that flu shots cannot cause infections since they consist of only fragments of the virus.
Yes, people might have a sore arm or mild fever after the shot, but that’s merely a response from the immune system, not actual illness.
Vaccines function similarly by showing the immune system a virus portion so it can respond faster to real infections. Consider your sneezing child or a cough nearby; the vaccine preps your immune system to act quickly afterward.
While building immunity, vaccines may generate some inflammation. A small study following 56 women after their shots found most reported mild arm soreness, typically resolving quickly.
Despite some women experiencing body-wide symptoms, all participants developed protective antibodies against the flu, regardless of their symptoms.
It’s still possible to catch the flu post-vaccination, but the shot can guard against severe complications.
Flu vaccines do help some prevent illness, but their main strength lies in avoiding severe consequences like hospitalizations and pneumonia. This is partly due to the way vaccines stimulate an immune response in various body regions via neutralizing antibodies that latch onto flu viruses and block infections.
Typically, flu viruses enter through the moist tissues of the nose and throat, which is where infection may start. Complete infection prevention would require different antibody types that act in those tissues. Some vaccines, like nasal sprays, promote this kind of immunity, but injectable vaccines generally offer more consistent protection.
Initial flu infections are usually mild, yet serious complications can develop, leading to hospitalizations or cardiovascular issues later on. Vaccination significantly reduces the risk of these severe complications.
Doctors have observed a rise in rare severe complications like acute necrotizing encephalopathy post-flu, more commonly found in unvaccinated individuals.
Recent evidence reviews indicate flu vaccination can reduce kids’ doctor visits by about 55% and hospitalizations by 67%. “Essentially, vaccination avoids around two-thirds of expected hospitalizations,” said Dr. Jake Scott from Stanford.
For adults under 64, flu vaccines lowered the chances of doctor visits or hospital admissions by 49% and 48%, respectively, while seniors saw similar reductions of 41% and 42%.
“We can’t expect a single shot to block all respiratory viruses, but they do significantly prevent severe repercussions,” Scott stated.
Pediatricians still strongly advise most children to get annual flu vaccinations.
In a recent update, the HHS has lessened the number of routinely recommended vaccines for American children, suggesting flu vaccination decisions should follow discussions with health care providers. Other vaccines are also in this consultation-based category.
Pediatricians express concern that this shift adds barriers to vaccination and might prevent necessary protection against serious illnesses. They believe discussions on benefits and risks have always been part of the vaccination process and see no need for heightened scrutiny without supporting evidence.
Some states and organizations, such as the American Academy of Pediatrics, maintain their recommendation for annual flu shots for children aged six months and older.
Last flu season saw 280 children die from flu-related complications, a non-pandemic record. Most of those deceased were unvaccinated, with many lacking preexisting health conditions.
Your flu shot choice should depend on age and personal preferences.
Since 2022, the CDC has recommended stronger vaccine types for those 65 and older—those featuring higher doses or adjuvants enhancing immune response. The brands Fluad, Flublok, or Fluzone high-dose are examples.
“These three vaccines provide about 25% more protection for older adults,” Schaffner commented, emphasizing the need for stronger immunity as age affects our defenses.
For those who prefer avoiding needles, the nasal spray FluMist is a viable option, especially for young kids or adults aged 18-49.
However, FluMist isn’t recommended for children under two, those over 50, pregnant women, or individuals with severely compromised immune systems.
