Welcome to this year’s flu season.
This year’s flu strain has already started to spread in 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, at the height of the H1N1 swine flu pandemic, has there been this number of flu cases so soon in the season.
Despite these figures, many people wonder if the flu is really such a serious disease. What is the benefit of the vaccine, especially if some people can still get the flu despite being vaccinated? Could you catch the flu from the vaccine? If you get the Covid shot, do you still need the flu shot?
To walk us through these questions and more, I spoke with Dr. Leana Wen, CNN medical analyst, emergency physician, public health expert, and professor of health policy and management at George Washington University Milken Institute. School of Public Health. She is also the author of “Lifelines: One Physician’s Journey in the Fight for Public Health.”
CNN: Is the flu a serious illness? What symptoms do people experience?
Dr AS Leana Wen: It can certainly be serious. The CDC estimates this flu caused between 9 million and 41 million illnesses, 140,000 to 710,000 hospitalizations and 12,000 to 52,000 deaths per year in the United States between 2010 and 2020.
Flu symptoms include fever, muscle aches, headache, fatigue, cough and runny nose. Many people recover within a few days, but some may still feel unwell for 10 days to two weeks after their symptoms start. Some will develop complications including sinus and ear infections, pneumonia and brain inflammation. The flu can also exacerbate underlying medical conditions – for example, people with chronic lung and heart disease may see their condition worsen due to the flu.
Even generally healthy people can get very sick from the flu. However, people particularly at risk of serious consequences include people aged 65 and over, young children under 2, pregnant women and people with underlying health conditions.
CNN: What’s the benefit of the vaccine, especially if some people can get the flu while they’re vaccinated?
Magnifying glass: The flu vaccine does two things. First and foremost, it reduces your risk of serious illness, i.e. being hospitalized or dying. Second, it can also lower your risk of getting sick from the flu.
In a way, it’s not too different from the Covid-19 vaccine. The most important reason to get the flu and coronavirus vaccine is to prevent serious illness. New data published in the latest CDC report on morbidity and mortality shows this year’s flu vaccine reduces the risk of hospitalization by approximately 50%. A 2018 study found that people who were vaccinated against the flu were 59% less likely to be admitted to intensive care because of the flu compared to those who were not vaccinated.
Vaccine efficacy may vary depending on vaccine compatibility with circulating influenza strains. The CDC quotes vaccine effectiveness against “medically assisted illnesses” ranging from 23% to 61% depending on year and vaccine-strain match. So it’s true that you could get the flu shot and still get the flu. But the vaccine reduces your risk – and, most importantly, it reduces the likelihood that you will end up very sick.
Another thing to consider is that there are many other virus that can cause flu-like symptoms. The flu vaccine helps protect against viral infections caused by influenza, but there are many other causes of viral syndromes, including adenovirus, rhinovirus, parainfluenza, and others. These other viruses also spread easily and there are no vaccines against them. I often hear patients say they got the flu the same year they got the flu shot, and that’s why they don’t want to get the flu shot anymore. But when I ask them if they have actually been diagnosed with the flu or if they just have flu-like symptoms, they say the latter.
CNN: Should children and pregnant women also get the flu shot?
Magnifying glass: Absolutely. These are groups particularly vulnerable to serious consequences, so it is very important that they receive the flu vaccine.
A study found that the flu vaccine reduces the risk of severe, life-threatening flu in children by 75%. Another one found that it cut flu-related emergency room visits in children by half.
Similar results are found in pregnant people. Not only the the flu vaccine protects the pregnant person, if the vaccine is given during pregnancy, it also helps to protect their baby against influenza during the first months of life. This is important because the flu vaccine is not available for babies until they are 6 months old or older.
CNN: Could you catch the flu from the vaccine?
Magnifying glass: No. The flu vaccine is a inactivated vaccine, which means that it does not contain the live virus and therefore cannot cause the flu. It is also a very well tolerated vaccine, the most common side effect being discomfort at the injection site which disappears after one day.
CNN: If you got the Covid-19 vaccine, do you still need the flu shot?
Magnifying glass: 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 receive the Covid vaccine (or bivalent recall) at the same time you get the flu shot, but at a different injection site.
CNN: Some people waited until later in the flu season to get their flu shot. Is it a good idea?
Magnifying glass: 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 encourage people who have not yet had the flu shot to do so now.
CNN: What should people know about flu treatments?
Magnifying glass: Most cases of influenza can be treated symptomatically, which means patients rest, hydrate, and receive treatment for symptoms that arise, such as anti-fever medications like acetaminophen or ibuprofen . There is also antiviral treatments available. These are really important for people at high risk of serious flu complications and/or who are very ill. The earlier these treatments are started, the better. An oral medication, oseltamivir (Tamiflu), can also be given to non-high-risk patients, too, within 48 hours of the onset of their illness.
I encourage everyone to have a flu plan, the same way they should have a Covid plan. Ask your doctor in advance if you should receive Tamiflu or other antiviral treatment. Know how you can get tested and where you can access treatment, including after hours and on weekends.
CNN: How can people avoid getting the flu?
Magnifying glass: Influenza is mainly transmitted by droplets — if an infected person coughs or sneezes, these droplets can land on someone else nearby. It is also possible that the droplets land on a surface, from which a person becomes infected after touching it and then touching their nose, mouth or eyes.
We can help reduce the transmission of the flu by staying away from others while we have symptoms. We should all cough or sneeze into our elbow or a tissue and wash our hands frequently, including after touching high-touch surfaces. People who are particularly vulnerable to severe consequences should consider wearing a mask to reduce their risk of contracting viral illnesses like the flu. And of course, get vaccinated!