Health authorities recommend getting your flu shot and COVID-19 booster at the same time. But should you get the two vaccines in the same arm?
The Centers for Disease Control and Prevention (CDC) recommends getting the flu shot and COVID-19 booster in different arms. In a press briefing, Ashish Jha, MD, MPH, the White House’s coronavirus response coordinator, said getting both vaccines at the same time may cause a similar or slightly higher incidence of side effects, but they tend to be mild.
However, individuals react to vaccines differently, so it’s hard to determine exactly how the placement will influence side effects.
The CDC advises providers to leave at least an inch of space between each injection site, if administered in the same arm. You can also choose to get vaccinated only in your non-dominant arm to avoid having pain in both arms.
People who are unable to get vaccinated in the upper arm can get the vaccines in the thigh. You can call your healthcare provider or vaccine site ahead of time to check if thigh injections are available.
Pedro Piedra, MD, a professor of molecular virology and microbiology at Baylor College of Medicine, recently received his booster and flu shot at the same time. Prior to the appointment, he expected the new COVID-19 booster to have more intense side effects than the flu shot. So he asked for the booster in his non-dominant arm, and the flu shot in the other.
“I did it on purpose because I wanted to be able to distinguish if I had a reaction,” Piedra told Verywell.
Surprisingly, the flu side hurt more, although the pain was mild and resolved within a day, he said. If you get your two shots in different arms, however, you can tell which vaccine caused more soreness and pain, he added.
Injection site soreness or pain can be caused by both the needle and the vaccine antigen.
“Any time you disrupt your skin, your muscles, your fibers, there is going to be inflammation,” Piedra said. “Even just with a needle poke, you’ll get stimulation, when you now put in a fluid, you cause some more local disruption.”
When vaccine antigen is added to the pinch, it is often recognized and picked up by the lymphatic system. The lymph nodes near the inoculation site may then swell or feel tender to touch.
The CDC recommends that adults 65 or older get a flu shot with a higher dosage than younger adults.
Adverse side effects were reported more frequently in those who received the higher-dose flu shot, compared to people who received the standard shot. The most common side effects included pain, redness at the injection site, headache, muscle aches, and malaise. However, they were mostly mild and resolved within a few days.
“As we get older, we really need a little extra kick in a way to ensure that we have a good immune response,” Piedra said.
He added that regardless of age, people should still get both shots at the same appointment.
How you want to take the injection really comes down to preference, according to Gregg Sylvester, MD, MPH, chief health officer of influenza vaccine company CSL Seqirus. Splitting up the shots may save you from some soreness, but more importantly, getting the two shots at the same time ensures maximum protection.
“With vaccines, it takes about two weeks for people to get fully protected,” Sylvester said. “If you go in and you get your COVID today and then you come back in two weeks to get your flu, you’ve got a window that you’re vulnerable.”
Getting your flu shot on the same day as your COVID-19 booster can be a good idea to ensure you are protected against both viruses. To dull the intensity of injection-site side effects, you may want to get the shots in different arms.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.