Covid & Flu Boosters Together or Separately?

By now you’ve probably heard there’s a new Covid booster available, designed to give greater protection from the Omicron variants BA.4 and BA.5. (New Covid Boosters Coming Soon) This is the first improvement in the Covid vaccine since its original production in 2020. This new vaccine will also provide protection from the original Covid variants.

Covid has now become endemic, just like influenza. That means we can expect it to remain in our population indefinitely, with seasonal variations, must like the flu. For most people, especially the elderly and those with compromised immune systems, this means an annual Covid booster, just like the flu. The question now is when to take the boosters and should they be taken together or separately?

The White House is promoting people take them together. That should make you skeptical right away.  Ashish Jha, White House Covid coordinator, on September 6th said, “I really believe this is why God gave us two arms — one for the flu shot and the other one for the Covid shot.” Does he really believe that was God’s motivation to give us two arms? On the other hand, Dr. Anthony Fauci, President Biden’s chief medical adviser, says, “Get your updated Covid-19 shot as soon as you are eligible.” So, should you follow the White House’s advice and get both boosters right away?

Medical experts may differ in their opinions, and they often do. But there is plenty of evidence to suggest separating the two boosters makes sense. The reason for this is based on the knowledge that flu vaccine effectiveness erodes pretty quickly over the course of a flu season. A vaccine dose given in early September may offer little protection at the height of the flu season which is usually in February or even March. “If you start now, I am not a big fan of it,” said Florian Krammer, an influenza expert at Mount Sinai School of Medicine in New York. “I understand why this is promoted, but from an immunological point of view it doesn’t make much sense.”

Helen Branswell, writing for, says a number of studies have shown that the benefit of a flu shot wanes substantially over the course of a flu season – exacerbating effectiveness problems that are frequently seen when some of the strains in the vaccine aren’t well matched to the strains making people sick. Work done by researchers from the Kaiser Permanente Vaccine Study Center and the Harvard School of Public Health estimate vaccine effectiveness declined by about 18% for every 28-day period after vaccination.

A study done by scientists at the Centers for Disease Control and Prevention (CDC) and elsewhere showed that the vaccine’s protection against flu that is severe enough to trigger hospitalization decreased by between 8% and 9% per month after vaccination. In older adults, who are more likely to get seriously ill from flu, the decline happened at a rate of about 10% to 11% per month.

“You’ve got about four months of pretty solid protection,” said Emily Martin, an associate professor of epidemiology who specializes in flu at the University of Michigan School of Public health. Martin was an author of this study.

When is the right time to get your flu shot?

Most experts will advise you to wait at least until the end of October to get a flu shot, though they’ll attach the caveat that if you start to hear about flu activity picking up where you live, you should accelerate your plans. “I’ll follow very carefully the activity in the community,” said Michael Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy. “If it starts to pick up, I’ll move immediately. Otherwise, I’m counting on sometime in late October, early November.”

As usual, getting your healthcare advice from the White House is probably a bad idea.