Welcome to this year’s flu season.
This year’s strain of flu has already begun to spread across the United States, according to new data from the US Centers for Disease Control and Prevention. There have been at least 880,000 flu cases, nearly 7,000 hospitalizations and, tragically, 360 flu deaths this fall, including one pediatric death. Not since 2009, during the height of the H1N1 swine flu pandemic, have there been so many flu cases this early in the season.
Despite these numbers, many people wonder if the flu is really such a serious illness. What is the benefit of the vaccine, especially if some people can get the flu despite being vaccinated? Could you get the flu from the vaccine? If you get the Covid shot, do you still need the flu shot?
To guide us through these questions and more, I spoke with CNN Medical Analyst Dr. Leana Wen, an emergency physician, public health expert, and professor of health policy and management at the George Washington Milken Institute School of Public Health. He is also the author of “Lifelines: A Doctor’s Journey in the Fight for Public Health.”
CNN: Is the flu a serious illness? What symptoms do people experience?
Dr. Leana Wen: It can definitely be serious. The CDC estimates that influenza caused between 9 and 41 million illnesses, 140,000 to 710,000 hospitalizations, and 12,000 to 52,000 deaths annually in the US between 2010 and 2020.
Flu symptoms include fever, muscle aches, headaches, fatigue, cough and runny nose. Many people recover within several days, but some may feel unwell as long as 10 days to two weeks after their symptoms start. Some will develop complications such as sinus and ear infections, pneumonia and inflammation of the brain. The flu can also worsen underlying medical conditions — for example, people with chronic lung and heart conditions may see their conditions worsen because of the flu.
Even generally healthy people can become very ill with the flu. However, those who are especially prone to serious effects include people age 65 and older, young children under 2, pregnant people, and people with underlying medical conditions.
CNN: What’s the benefit of the vaccine, especially if some people can get the flu despite being vaccinated?
Wen: The flu shot does two things. First and foremost, it reduces the chance of serious illness — that is, being hospitalized or dying. Second, it can also reduce your chance of getting the flu.
In a sense, this is not very different from the Covid-19 vaccine. The most important reason to get vaccinated against both the flu and the coronavirus is to prevent serious illness. New data published in the CDC’s latest morbidity and mortality report show that this year’s flu shot reduces the risk of hospitalization by about 50 percent. A 2018 study found that people who got the flu shot were 59% less likely to be admitted to the ICU because of the flu compared to those who weren’t vaccinated.
The effectiveness of the vaccine can vary depending on how well the vaccine matches the circulating strains of influenza. The CDC reports vaccine effectiveness against “medically monitored disease” from 23% to 61% depending on the year and vaccine-strain match. So it is true that you could get the flu shot and get the flu. But the vaccine does reduce the chance of that happening – and, importantly, it reduces the chance that you’ll end up very sick.
Another thing to consider is that there are many other viruses that can cause flu symptoms. The flu vaccine helps protect against viral infections caused by influenza, but there are many other causes of viral syndromes, including adenoviruses, rhinoviruses, parainfluenza, and others. These other viruses spread easily, too, and there are no vaccines against them. I often hear patients say that they once got the flu the same year they got the flu shot and that’s why they don’t want to get vaccinated again. But when I ask them if they were actually diagnosed with the flu or just had flu symptoms, they would say the latter.
CNN: Should children and pregnant women also get the flu shot?
Wen: Absolutely. These are groups particularly vulnerable to serious outcomes, so it is very important that they receive the flu vaccine.
One study found that the flu vaccine reduces children’s risk of severe, life-threatening flu by 75%. Another found it halved flu-related emergency department visits in children.
Similar results are found in pregnant women. The flu vaccine not only protects the pregnant person, but if the vaccine is given during pregnancy, it also helps protect their baby from the flu for the first few months of his life. This is important because the flu vaccine is not available to babies until they are 6 months or older.
CNN: Could you get the flu from the vaccine?
Wen: No. The flu vaccine is an inactivated vaccine, meaning it does not contain the live virus and therefore cannot cause the flu. It is also a very well-tolerated vaccine, with the most common side effect being discomfort at the injection site which is gone after a day.
CNN: If you got the Covid-19 shot, do you still need the flu shot?
Wen: Yes. Different vaccines target different viruses. The Covid vaccine helps protect against Covid but does not protect against the flu and vice versa. You can get the Covid vaccine (or the bivalent booster) at the same time as the flu vaccine, just at a different injection site.
CNN: Some people waited until later in the flu season to get the flu shot. Is this a good idea?
Wen: At this point, no, because it is now clear that this flu season is starting earlier than usual. Cases are already high and it takes about two weeks to achieve optimal immune protection after vaccination. I would encourage people who have not yet received the flu shot to do so now.
CNN: What should people know about flu treatments?
Wen: Most cases of the flu can be treated symptomatically, meaning patients rest, hydrate, and receive treatment for symptoms that occur — such as fever-reducing medications such as acetaminophen or ibuprofen. Antiviral treatments are also available. These are really important for people at high risk for serious flu complications and/or who are very sick. The earlier such treatments are started, the better. An oral drug, oseltamivir (Tamiflu), can also be given to non-high-risk patients within 48 hours of the onset of their illness.
I would encourage everyone to have a flu plan, the same way they should have a Covid plan. Ask your doctor beforehand if you should take Tamiflu or other antiviral treatment. Find out how you can get tested and where you can access treatment, including opening hours and weekends.
CNN: How can people prevent the flu?
Wen: The flu is spread mainly through droplets – if an infected person coughs or sneezes, those droplets can land on someone else nearby. It is also possible for droplets to land on a surface, from which someone becomes infected after touching it and then touching their nose, mouth or eyes.
We can help reduce the spread of the flu by staying away from others while symptomatic. We should all cough or sneeze into our elbow or a tissue and wash our hands often, even after touching high-touch surfaces. People who are particularly vulnerable to serious outcomes should consider wearing a mask to reduce their chances of contracting viral illnesses such as the flu. And, of course, get vaccinated!
