Skip to content
Home » Flu and COVID “twindemic” – more reasons to get both vaccines

Flu and COVID “twindemic” – more reasons to get both vaccines

Infectious disease and public health experts are beginning to worry about a twindemic of flu and COVID-19 as we enter the winter. The start of the 2021-22 flu season added to the ongoing COVID-19 pandemic may make this winter particularly dangerous.

As I discussed previously, much of the world had the fewest cases of influenza than any time in recent history. COVID-19 pandemic mitigation, such as face masks, social distancing, fewer people traveling, fewer kids in school, and more people working remotely left precious little opportunity for the influenza virus to spread like it does in “normal winters.”

With the good news comes some potentially bad news. This article will look into reasons why a flu and COVID-19 twindemic may be coming to many countries across the world, including the USA. I don’t want to be the harbinger of the apocalypse, but I just want to present more reasons for everyone to get both the flu and COVID-19 vaccine to prevent this potential twindemic.

flu COVID-19 twindemic

Why the flu season may be worse this year?

The USA and much of the world got a break from the flu last year because of the mitigation tactics that most of the world employed. It probably kept the COVID-19 pandemic from becoming much worse and just pushed the typical influenza outbreaks into essentially statistical noise.

Right about now, the Southern Hemisphere would be coming off its flu season, and the virus moves north during the winter. OK, the virus doesn’t migrate, it’s just that winter brings conditions that the few cases of flu start finding more hosts. However, the Southern Hemisphere did not have much of a flu season during their winter, again, probably as a result of COVID-19 mitigation measures.

Outpatient hospital visits for cases of influenza for the week of Sept. 27, 2021, compared to previous seasons. (

However, the world may not be so lucky in 2021-22.

According to researchers at the University of Pittsburgh Schools of the Health Sciences projections, there could be up to 20% more flu cases than a normal year, with the potential to see nearly twice the typical caseload. The Centers for Disease Control and Prevention estimate average annual flu cases in the USA are between 9-45 million cases causing 12-52 thousand deaths.

In one preprint study from researchers at the University of Pittsburgh, researchers hypothesized that low flu cases in 2020-21 could lead to a “compensatory second season” this year with young children especially at risk because of little to no prior immunity.

In a second preprint study, other researchers at the University of Pittsburgh suggested that hospitalizations could rise to 600,000 unless flu vaccine uptake increased significantly. In 2019-2020, there were 400,000 hospitalizations in the USA for the flu.

Dr. Mark Roberts, director of the Public Health Dynamics Laboratory at Pitt Public Health and an author on both preprint studies, stated that just because a “twindemic” was avoided in 2020-21, doesn’t mean it’s impossible during the upcoming flu season. He said,

If anything, our models show that we should be more concerned this year about the possibility of a surge in COVID-19 hitting at the same time as a massive flu outbreak in areas of the country with low vaccination rates against both diseases.

The United States seems to be leaving a period of a significantly higher number of COVID-19 cases related to the delta variant. Most forecasting models suggest that weekly cases and deaths will decline through November. However, many are predicting another surge after the Thanksgiving through New Years’ holidays.

Copyright Philadelphia Inquirer, 2021

What are the issues with the flu & COVID-19 twindemic?

First, since both diseases share many symptoms, such as fever, chills, coughs, fatigue, and difficulty in breathing, healthcare providers will have to administer numerous tests to diagnose and treat the correct virus.

Second, because of the low incidence of influenza during the past winter, most researchers don’t know how the two respiratory viruses might interact. Someone who contracts both diseases at the same time could have more serious and significant complications than either disease exhibits alone.

Third, healthcare resources could be further stretched to the breaking point if hospitals are trying to treat a large number of COVID-19 and flu patients during a twindemic. It could make it a lot worse than the highest points of the COVID-19 pandemic.

person holding a vaccine
Photo by Karolina Grabowska on

What to do about this twindemic?

Let’s be clear – both the COVID-19 and flu vaccines are your best choice. Of course, children under 12 are not yet approved for the COVID-19 vaccines, but the very safe and very effective flu vaccine is recommended for anyone above the age of 6 months.

The CDC has stated that the seasonal flu and COVID-19 vaccines can be given at the same time, you do not have to wait for one or the other, just get them both.

Flu vaccine uptake, during the 2019-20 flu season prior to the pandemic, was about 52% of all eligible people in the USA. That number included nearly 64% of children under 18 and 70% of adults over 65. Those are good numbers, but far below the level necessary to slow a flu outbreak.

Furthermore, I’m much more concerned about anti-vaccine sentiment today than I was in 2019. I’m worried that the anti-COVID-19 vaccine will filter over to other vaccines, especially the flu vaccine which gets attacked with about as many myths as does any other vaccine.

During this time of the COVID-19 pandemic, the flu vaccine has other benefits. It has been established that it prevents serious illness and hospitalization, which keeps people from severely impacting healthcare resources. Also, it reduces symptoms that might be confused with COVID-19.

If you live in the Northern hemisphere, get your flu vaccine before the end of October. And get your COVID-19 vaccination (or booster) too. At the same time if necessary.

The flu kills, and in some years, it can be nearly as bad as COVID-19. We do not want to have this twindemic – it will be a public health disaster.

Did I mention that you should get both vaccines? Please do it now.

Michael Simpson

Don’t miss each new article!

We don’t spam! Read our privacy policy for more info.

Liked it? Take a second to support Michael Simpson on Patreon!
Become a patron at Patreon!