Who should get the flu vaccine and why? Our medical analyst explains

CNN
 — 

Welcome to this year’s flu season.

This year’s flu strain has already begun spreading across the United States, according to new data from the US Centers for Disease Control and Prevention. There have been at least 880,000 cases of influenza, nearly 7,000 hospitalizations and, tragically, 360 deaths from the flu this fall, including one pediatric death. Not since 2009, during the height of the H1N1 swine flu pandemic, have there been this many cases of influenza so early in the season.

Despite these numbers, many people wonder if the flu is really that serious of an illness. What’s the benefit of the vaccine, especially if some people may still get the flu despite being vaccinated? Could you get the flu from the vaccine? If you get the Covid vaccine, do you still need the flu vaccine?

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 University Milken Institute School of Public Health. She 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 certainly can be serious. The CDC estimates that flu resulted between 9 million and 41 million illnesses, 140,000 to 710,000 hospitalizations, and 12,000 to 52,000 deaths annually across the US between 2010 and 2020.

Symptoms of the flu include fever, muscle aches, headaches, fatigue, coughing and a runny nose. A lot of people recover within several days, but some may still be feeling unwell as long as 10 days to two weeks after the onset of their symptoms. Some will develop complications, including sinus and ear infections, pneumonia, and inflammation of the brain. The flu can also exacerbate underlying medical conditions — for example, people with chronic lung and heart diseases can see their conditions worsen due to the flu.

Even generally healthy people can become very ill due to the flu. However, those particularly susceptible to severe outcomes include those 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 may get the flu despite being vaccinated?

Wen: The flu vaccine does two things. First and most importantly, it reduces your chance of severe illness — that is, of being hospitalized or dying. Second, it can also reduce your likelihood of getting sick from the flu at all.

In a sense, this is not too different from the Covid-19 vaccine. The most important reason to get vaccinated against both the flu and the coronavirus is to prevent severe illness. New data released in the CDC’s latest morbidity and mortality report shows this year’s flu vaccine reduces the risk of hospitalization by about 50%. A 2018 study found that people vaccinated against the flu were 59% less likely to be admitted to the ICU due to influenza when compared with those who were unvaccinated.

The vaccine’s effectiveness can vary depending on how well matched the vaccine is to circulating influenza strains. The CDC cites vaccine effectiveness against “medically attended illness” anywhere from 23% to 61% depending on the year and vaccine-to-strain match. It’s true, then, that you could get the flu vaccine and still contract the flu. But the vaccine does reduce your chance thereof — and, crucially, it reduces the likelihood that you could end up very ill.

Another thing to consider is that there are a lot of other viruses that can cause flu-like symptoms. The flu vaccine helps protect against viral infections caused by influenza, but there are a lot of other causes of viral syndromes, including adenovirus, rhinovirus, parainfluenza and others. These other viruses spread easily, too, and there aren’t vaccines against them. I often hear patients say they once got the flu the same year they had a flu vaccine, and that’s why they don’t want to get vaccinated again. But when I ask them whether they were actually diagnosed with the flu or just had flu-like symptoms, they would say the latter.

CNN: Should children and pregnant people also get the flu vaccine?

Wen: Absolutely. These are groups particularly vulnerable to severe outcomes, so it’s very important they receive the flu vaccine.

One study found the flu vaccine reduces children’s risk of severe life-threatening influenza by 75%. Another found it reduced flu-related emergency department visits in children by half.

Similar results are found in people who…