Indications are that this year's flu season is going to be particularly nasty, making the annual influenza vaccine even more important than usual, infectious disease experts say.
People already are landing in the hospital with severe cases of influenza, about a month ahead of when flu season usually begins, said Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases.
That tracks with flu activity this year in Australia, which had an early and moderately severe influenza season, Schaffner said. Because the seasons are reversed between the United States and Australia, infectious disease experts here look to that continent to predict upcoming flu activity.
“We anticipate a notable influenza season this year. We've had two mild preceding seasons — largely, we think, because we've been sheltering at home, wearing masks, being cautious about travel and children have not been in school,” Schaffner said.
“Well, the children are back in school," he added. "We've taken off our masks. We're traveling. We're visiting friends and relatives. We're going to houses of worship, restaurants. We're going back to business. We're doing all those things. And this will provide an environment for the influenza virus really to spread.”
Unfortunately, many people remain vaccine-hesitant. Only about half of people who were eligible got a flu shot during the 2020-2021 season, according to the U.S Centers for Disease Control and Prevention.
Here's some important information about the vaccine that can help inform your decision:
How effective is the flu vaccine?
Each year, vaccine-makers look to the flu viruses circulating in Australia to guess what strains will be predominant when the U.S. influenza season rolls around.
“We try to anticipate what the most common circulating strains will be nine months from now. That's when you decide which strains to incorporate in the vaccine,” Schaffner said. “We're pretty good at hitting the target. But there's some years when we're off target, and that reduces the effectiveness of the vaccine.”
Generally, the flu vaccine reduces the number of people who get sick by 40% to 60%, experts say. Interim numbers say last year the shot fell far short of the mark, providing about 35% effectiveness against circulating influenza A strains, according to the CDC.
But even a relatively ineffective flu shot confers solid protection against severe disease and hospitalization.
During the 2019-2020 flu season, vaccination prevented an estimated 7.5 million cases of flu; 3.7 million flu-related medical visits; 105,000 hospitalizations due to flu; and 6,300 flu-associated deaths, the CDC reported.
Further, a 2021 study showed that vaccinated flu patients had a 26% lower risk of admission to an intensive care unit and a 31% lower risk of dying from flu compared to the unvaccinated, the CDC stated.
“My patients would come in after flu season and complain, 'you vaccinated me against influenza but I got influenza anyway,'” Schaffner said. “And I would say, 'Charlie, I'm so glad you're here to complain.'”
When's the best time to get a flu shot?
The CDC recommends October as the best month to get vaccinated for influenza, Schaffner said.
“It's the best balance between getting the vaccine early enough to prevent early flu — and as a matter of fact, flu is a bit early this year — while also extending that protection for many people beyond February, which is usually the peak month for flu in the U.S.,” he explained.
But if you miss October, don't let that stop you from getting the shot, Schaffner added. It takes 10 to 14 days for your immune system protection to build up.
“If somehow you skip doing it in October, please, by all means, go ahead and still get the vaccine,” Schaffner said. “Because, as I said, by and large, flu peaks in the United States in February.”
Is it safe to get the COVID booster along with the annual flu shot?
The CDC is recommending that people get both the new bivalent COVID booster as well as the annual flu vaccine this fall.
“Flu vaccine cannot protect against COVID. COVID vaccine cannot protect against flu. They're separate viruses. You have to get both vaccines,” Schaffner said. “This year, we're asking everyone to roll up both sleeves.”
Not only is it safe to get both shots, but it's safe to get them both during the same visit to your doctor, pharmacy or health clinic, he said.
“It is safe and it is OK to give both vaccines simultaneously, if you choose to do that,” Schaffner said. “If you choose to spread them out, there's no required interval between the two. You can get one today and the next one tomorrow if you choose. But I always remind people that a vaccine postponed is, unfortunately, often a vaccine never received, so you're going to have to be mindful and diligent about getting both.”
How much cash will I need to shell out for a shot?
Medicare, Medicaid and most private health insurance plans cover flu shots as a free preventive health measure, Schaffner said. The cost of a vaccination is far less than the cost of an ER visit or hospitalization due to influenza.
People without insurance can get a free flu shot from their local health department.
Should seniors get the flu shot? What about pregnant women or young children?
People 65 and older are at higher risk for contracting severe influenza, which can lead to potentially fatal complications like pneumonia. Influenza also increases an older person's risk for heart attack and stroke.
This year, the CDC's Advisory Committee on Immunization Practices for the first time specifically recommended three high-powered flu vaccines for seniors. These vaccines are specially designed to provide a more powerful immune response.
“If you look back at people age 65 and older who received flu vaccine last year and the year before and the year before that, already 80% of that population was receiving one of these three vaccines, so medical practice had been moving in that direction in a steady way already,” Schaffner said.
“But this year for the first time they've said the data are now sufficient that you should get one of these vaccines if you are 65 and older, and get the standard vaccine only if one of these vaccines is not available,” he added.
Expectant moms also should get the vaccine, both to protect themselves from pregnancy complications caused by influenza and to give their newborns early protection.
“A number of studies now have shown with great conclusiveness that influenza vaccine administered during pregnancy is safe both for the mom and for the baby,” Schaffner said.
He noted that pregnant women who get the flu have complication rates that are comparable to those among senior citizens.
“In other words, there is increased risk of the complications of influenza simply because of their pregnancy status,” he said.
“Further, the antibodies created by the lungs actually cross the placenta and go into the newborn, and they help protect the newborn during the first 4 to 6 months of the newborn's life,” Schaffner said. “So by vaccinating the pregnant woman, you protect not only her, but you protect that newborn baby. It's a two-fer.”
Children become eligible for flu shots at 6 months of age. These shots can be lifesaving for children, the CDC says. A 2022 study found the flu vaccine reduces a kid's risk of life-threatening influenza by 75%, while a 2020 study found that flu vaccine reduces flu-related hospitalization by 41% among children.
What side effects should I expect? Will the shot give me the flu?
“It is an extraordinarily persistent urban and rural myth that you can get flu from the flu vaccine,” Schaffner said. “That simply is biologically impossible. It cannot happen.”
People often think they've gotten the flu from their vaccination because the shot's side effects are similar to those of a case of influenza, he noted.
“Some people do get a little bit of headache, maybe even get a degree of fever and feel out of sorts for a day,” Schaffner said. “That's not flu. That's your body responding to the vaccine.”
Other common side effects from the shot are a sore arm and some redness or swelling at the injection site, Schaffner added.
The U.S. Centers for Disease Control and Prevention has more about the 2022-2023 flu season.
SOURCES: William Schaffner, MD, medical director, National Foundation for Infectious Diseases, Bethesda, Md.; U.S. Centers for Disease Control and Prevention; Vaccines.gov