With talk of the COVID-19 vaccines dominating the conversation, it’s important not to forget the importance of the flu shot as flu season approaches. However, some might be getting ready to get a COVID-19 vaccine and wonder if they must wait before getting either shot. Updated guidance from the Centers for Disease Control and Prevention (CDC) says waiting isn’t necessary and that the flu and COVID-19 shots can be administered at the same time.
This reflects a change from previous guidelines where the CDC recommended waiting 14 days in between different shots.
“This was out of an abundance of caution during a period when these vaccines were new and not due to any known safety or immunogenicity concerns,” the CDC said. “However, substantial data have now been collected regarding the safety of COVID-19 vaccines currently approved or authorized by FDA.”
Now, the flu and COVID-19 shots may be co-administered “without regard to timing of other vaccines,” according to the CDC. The agency says if multiple vaccines are given at a single visit, they must be administered at different injection sites, but can be in the same region. For example, for adults and adolescents, multiple vaccines can be given in the same deltoid muscle but at different sites in the muscle.
Interestingly, studies show that the flu shot can even be protective against severe COVID-19 symptoms.
A recent study by University of Miami researchers published in PLOS ONE shows that receiving the influenza vaccine led to reduced adverse outcomes due to COVID-19 infection. This included reduced risk of sepsis, stroke, deep vein thrombosis (DVT) and admission to the intensive care unit (ICU).
The researchers retrospectively screened deidentified records of over 73 million patients who tested positive for COVID-19. The patient records were mainly from the US but also spanned the UK, Italy, Germany, Israel and Singapore. The researchers then narrowed down the records to two propensity score matched 37,377-patient cohorts (N = 74,754).
Analysis of these records revealed that people who did not receive the flu vaccine were 20 percent more likely to be admitted to the ICU with COVID-19 than those who received the vaccine.
The unvaccinated group was also up to 58 percent more likely to visit an emergency department (ED) due to COVID-19 and up to 58 percent more likely to have a stroke. There was no link found between immunization against influenza and death due to COVID-19.
Previous studies have also found associations between getting the flu shot and improved COVID-19 outcomes.
For example, a study last year found that the flu shot was protective against COVID-19 among healthcare workers, with reduced severity of symptoms in those that tested positive for the coronavirus.
Some investigators hypothesize that there may be biological mechanisms that can explain why the flu shot may offer protection against the effects of COVID-19, including early, non-specific activation of the immune system and mechanisms involving ACE2 receptor expression (the receptor that primarily mediates entry of SARS-CoV-2 into human cells).
However, the influenza vaccine is not designed to protect against SARS-CoV-2 specifically and neither does it increase overall immunity.
Instead, the protection is likely explained by personal attitudes and behaviors. For example, people that get their flu shot may be more health conscious and take measures to protect their personal health. This may include regular handwashing, distancing and other measures that may lead to protection against influenza as well as COVID-19. People who receive the flu shot are also generally more educated and in higher income brackets.
Flu and COVID-19 Shots for Flu Season
Last year’s flu season was one of the mildest ones in recent history, owing largely to pandemic measures of lockdowns, masks and physical distancing, as well as reduced travel. This helped avoid the “twindemic” of influenza and COVID-19 that experts had been fearing.
According to an article in JAMA, of the 1.3 million specimens reported to the CDC and tested for influenza, 2,136 tested positive for influenza, and there were 748 influenza deaths. There were likely more deaths related to the flu as not all deaths are reported to the CDC. However, the numbers are still striking compared to the 2019–2020 flu season in which there were more than 38 million people that got sick from influenza with 22,000 deaths.
As we head into flu season, infectious disease expert Dr. Anthony Fauci advised people to get vaccinated — against both influenza and COVID-19 — in an interview with CNN on Monday.
“What you should do is get it as soon as you can and in the most expeditious manner,” Fauci said of the flu shot. “If that means going in and getting the flu shot in one arm, the COVID shot in the other, that’s perfectly fine. There’s nothing wrong with that at all. In fact, that might make it more convenient.”