September 22, 2020

Flu shot Q & A: Does COVID-19 change our approach?

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KPWHRI’s Michael L. Jackson, PhD, MPH, talks about influenza vaccine research in the age of the pandemic

Doctors recommend getting a flu shot annually—advice that’s particularly important this year as the COVID-19 pandemic continues.

Michael L. Jackson, PhD, MPH, a senior investigator at Kaiser Permanente Washington Health Research Institute, conducts research on preventing, tracking, and predicting the spread of infectious diseases, including influenza and COVID-19. Here, he answers questions about the common—but serious—threat the flu poses during a season made particularly risky due to the pandemic.

Q. With so much emphasis on social distancing during the pandemic, some people may feel hesitant about going into a clinic to get a flu shot. Is it worth the effort and the risk?

Absolutely. Flu vaccine can reduce your risk of influenza, which is a serious illness. Some 30,000 to 40,000 people die each year in the United State from the flu, and hundreds of thousands are hospitalized. So, avoiding this illness is important, and particularly now as we face the double risk of flu and COVID-19.  That’s why Kaiser Permanente encourages all adults and children over age of 6 months to make an appointment now to get a flu shot.

Influenza and COVID-19 do have many similar symptoms. This means that people who get the flu won’t know if they have influenza or COVID-19. Apart from the fact that influenza can cause serious illness, getting sick with the flu will have the additional stress of worrying whether it might be COVID-19.

Keeping flu cases to a minimum will also reduce the strain on the health care system this winter, which is critical.

Q. Can the flu vaccine protect against COVID-19?

No. Influenza and COVID-19 are both respiratory illnesses, but they caused by different viruses.

Q. According to the CDC, flu vaccine typically reduces your risk of getting the flu by 40% to 60%? Why is not higher than that?

Influenza is not like the measles where we have one universal vaccine that fights a single virus.  Instead, there are several strains of flu. “A” and “B” are the most common flu strains, and within each, there are subdivisions based on different proteins on the surface of the virus—such as H1N1 and H3N2. 

Because it takes several months to make flu vaccines, we must predict in February which flu strains are most likely to be circulating in the fall and winter. The majority of the time, we get it right, but sometimes we get it wrong and the vaccine is not as effective as we’d like it to be.

Effectiveness can also vary in individual people. For example, the first flu strain a person is exposed to as a child can set their immune response for the rest of their life. You may have challenges maintaining immunity to viruses you weren’t exposed to early on.

Also, flu viruses mutate quickly in human populations. A person may have been infected a few years ago with a particular strain that comes back later, but the proteins have changed shape and antibodies in their immune system don’t bond as well to newer forms of the virus. So we need to keep updating and distributing new flu vaccines to respond to mutations as viruses travel around the world.

Q. What research is underway to increase flu vaccine effectiveness?

Some research teams are working on ways to boost the immune response that flu vaccines can produce in certain populations.  For example, we’ve found that adding an adjuvant (an ingredient that boosts the immune response) to vaccines can help make flu vaccines more effective for seniors. Increasing the dose can also help in older populations.

Work is also underway to help vaccine manufacturers more rapidly scale up production.  That might result in less of a mismatch between flu vaccines and the viruses that circulate each year.  Currently, most flu vaccines are made by growing virus samples in chicken eggs, which is a lengthy process.  But new approaches under development use cell cultures, which can happen much faster.

Q. Do you think there will ever be a universal vaccine so that we wouldn’t need to get a shot each year?

I hope so, but the science is not there yet.  Some research teams are working on vaccines that would target parts of flu virus proteins that don’t mutate as quickly as the surface does in the hope that vaccines would last longer than a year.  But I can’t speculate when that might be possible. 

Q. So what’s the bottom line?

Get your flu shot this year.  If you do this, along with practices that prevent the spread of COVID-19 (i.e., social distancing, mask wearing, hand washing), you’ll greatly reduce your risk of serious illness.  Plus, you’ll reduce the risk for others, including our most vulnerable populations.

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