Here’s Why Seasonal Flu Vaccines Only Last a Few Months

  • With the COVID-19 pandemic already straining healthcare centers, this year it’s more important than ever to get your annual flu shot.
  • The flu virus changes yearly as multiple strains spread throughout the community and the virus adapts itself for survival.
  • It takes between 3 and 4 weeks for someone to develop immunity against the predicted strains of influenza after getting the flu shot.

The current pandemic has overwhelmed us with concerns about COVID-19, but there’s a disease that routinely causes tens of thousandsTrusted Source of deaths.

It affects millions of Americans every year, and it’s called influenza.

With the COVID-19 pandemic already straining healthcare centers, this year it’s more important than ever to get your annual flu shot.

While vaccination rates are relatively highTrusted Source in the United States overall, the number of people getting their annual flu shot falls far belowTrusted Source other vaccination rates.

One reason is that people have to get them every year, unlike vaccines for measles or mumps that require only a few doses for a lifetime.

So why doesn’t the vaccine protect us long term?

Influenza changes every year

Dr. Theodore Strange, associate chair of medicine at Staten Island University Hospital in New York, explained that the flu virus changes yearly as multiple strains spread throughout the community and the virus adapts itself for survival.

“That is why no long-term immunity,” said Strange. “It essentially ‘changes its coat’ — H1N1, H2N3, and so on.”

He emphasized that the flu vaccination program typically needs to start early to capture as many people as possible. It takes between 3 and 4 weeks for someone to develop immunity against the strains of influenza predicted in a given year.

Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York, cautioned that “antibody responses for seasonal vaccines, like flu vaccine, which change every year, typically do fall off after 3 to 6 months.” That’s why the timing of the flu vaccine is important.

Horovitz pointed out that while the virus mutates, that’s not the only reason you need an annual vaccination.

“There are mutations of the coronavirus as well, [but] it’s not necessarily because of that that you need to have an annual vaccine,” said Horovitz. “It just may be that the antibody response doesn’t last more than a year, and so a re-vaccination is important.”

Flu season and COVID-19

According to the most recent figures from the Centers for Disease Control and Prevention (CDC)Trusted Source, influenza has resulted in up to 45 million illnesses, between 140,000 and 810,000 hospitalizations, and between 12,000 and 61,000 deaths every year since 2010.

However, this year is different. The possibility of a bad flu season combined with the COVID-19 pandemic could bring our healthcare system to the point of failure.

“Thirty to forty thousand people a year die of influenza; you complicate hospitalizations from influenza with any kind of surge in the coronavirus and you’ve overwhelmed the hospital system, which is something we worried about back in the spring with coronavirus,” Horovitz told Healthline.

Who should and shouldn’t get a flu shot

The CDC specifiesTrusted Source exactly who should get a flu shot this fall, and different flu shots are approved for people of different ages. It’s critical that everyone receive the vaccine that’s appropriate for their age.

  • Inactivated influenza vaccines (IIV) are approved for those as young as 6 months of age.
  • Recombinant influenza vaccines (RIV) are approved for people 18 years and older.
  • Adjuvanted and high-dose inactivated vaccines are approved for people 65 and older.

There are instances when the vaccination isn’t recommended.

According to the CDCTrusted Source, children younger than 6 months and people allergic to ingredients used in the vaccine shouldn’t be vaccinated.

Also, if you have ever experienced Guillain-Barré syndrome, you should speak with your doctor before getting the shot.