A Rutgers infectious disease expert explains why getting the annual flu shot is important to individual and public health

While social distancing and wearing masks kept the 2021-2022 flu season milder than pre-pandemic levels, experts who expect flu cases to rise this year as COVID-19 restrictions are lifted are urging people to get their flu vaccine to prevent the nation’s health care system from being overwhelmed by influenza and the pandemic.

David Cennimo, an infectious disease expert at Rutgers New Jersey Medical School, discusses what you can do to protect yourself during the upcoming flu season.

What can we learn from last year’s flu season and what should we expect this year?
According to the Centers for Disease Control and Prevention (CDC), the 2021–2022 flu season was mild and driven by A(H3N2), a strain that was covered in last year’s vaccination and is being included in 2022–2023 vaccines.

The CDC’s preliminary figures from last season show 8,000,000 to 13,000,000 flu illnesses, 82,000 to 170,000  flu hospitalizations and 5,000 to 14,000 flu deaths. However, as precautions loosen, we are seeing rates rise. Pediatric deaths, for example, rose from one death in the 2020–2021 season to 33 this past season. In comparison, 199 children died from influenza in the 2019–20 flu season.

When is the optimal time to get a flu shot?
The CDC recommends that people age 6 months or older receive a flu vaccination, which is effective for about six months, by late October. The vaccine is effective for about six months so if you get vaccinated too early there is a chance your immunity might wane. Certain children may need a booster shot after the initial vaccination. Check with your doctor.

The nasal mist vaccine is an effective alternative for people between ages 2 to 49 with normal immune systems. It is not for pregnant women, children receiving aspirin or asthmatics under age 4.

Can you get COVID-19 and flu shots at the same time?
Yes. The CDC originally recommended a two-week spacing between COVID-19 and other vaccinations, since it was closely monitoring reactions for this new vaccine. Now you can get your COVID-19 shot or booster and flu vaccination at the same time. Studies show having them together does not affect efficacy.

Who is especially vulnerable for contracting the flu?
Everyone 6 months of age or older should be vaccinated, but it is especially important for those who are at higher risk for complications and mortality. The CDC estimates that 70 percent to 90 percent of annual flu deaths are in people over 65. Vaccination is important for people with chronic conditions like heart disease and is also critical for caretakers and essential workers who are more likely to transmit the virus if not vaccinated.

Pregnant women should receive the flu shot to prevent severe symptoms and help confer some immunity to their newborns.

Black, Hispanic, American Indian and Alaska Natives also had higher rates of hospitalization and intensive care unit admission for the flu according to the CDC, so flu vaccination is important.   

How can one person’s flu vaccination possibly save lives?
As we have seen with asymptomatic cases of COVID-19, people can unknowingly have the flu and gravely affect vulnerable elderly, children and those who have impaired immune systems, such as cancer patients and people with HIV or pulmonary disease. The more you suppress influenza through vaccination, the less opportunity the virus has to mutate and infect more people. You’ll also have lower viral loads and will shed the virus – and be infectious – for shorter periods of time.

How can a flu shot help me if I do contract the flu?
Getting a flu shot reduces your odds of getting sick. If you do, your illness would be less severe. A 2018 study found that flu vaccination among adults reduced the risk of being admitted to an intensive care unit with flu by 59 percent and 2014 study showed that flu vaccination reduced children’s risk of flu-related pediatric intensive care unit admission by 74 percent.

How are the coronavirus and the flu similar and different?
Both are spread predominantly through respiratory droplets and contact. There seem to be more asymptomatic cases of coronavirus than influenza, but both are capable of being spread before a person knows they are infected – about one to two days before symptoms appear.

Influenza contagiousness is usually over within a week, while coronavirus is around 10 days. Both can cause a spectrum of illness ranging from mild to critical illness and death. Flu symptoms can be confused with COVID-19. If you start feeling ill, it is important to quarantine and test for COVID-19 to rule it out.

Are influenza vaccines safe?
Flu vaccines are the most tested and adverse effects are small. Extremely rare side effects – like allergic reaction – can happen, but the risk is still lower than with many other common medications. Unless someone with an egg allergy has had an allergic reaction to the flu vaccine in the past, they should get the vaccine. If their allergy is serious, they should be monitored while taking the shot. Also, there are two vaccines not made in eggs: rIIV, a recombinant protein, and ccIIV, which is made in cell culture.

Are any of the available flu vaccines recommended over others? 
Yes, for some people. For the 2022–2023 flu season, the CDC preferentially recommends three vaccines for people 65 years and older – Fluzone High-Dose Quadrivalent vaccine, Flublok Quadrivalent recombinant flu vaccine or Fluad Quadrivalent adjuvanted flu vaccine – over standard-dose unadjuvanted flu vaccines.  

Can you get the flu from the flu vaccine?
The vaccine takes two weeks to be effective, so people still could contract the flu during this period. The vaccine exposes your body to a weakened form of the virus, which allows you to mount an immune response. ​Essentially, you are getting a “mini flu” illness, which is why some people may feel ill after getting the vaccine.