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What is the Association Between COVID-19 Deaths and Flu Vaccination Rates?

Is there an association between COVID-19 deaths and flu vaccination rates?

There actually is!

What is the Association Between COVID-19 Deaths and Flu Vaccination Rates?

In general, several studies have found lower rates of COVID-19 deaths in folks who have been vaccinated and protected against the flu.

“There could be several independent or linked explanations for this significant association, including a possible protective effect of influenza vaccination against COVID‐19 acquisition or disease.”

Marín‐Hernández et al on Epidemiological evidence for association between higher influenza vaccine uptake in the elderly and lower COVID‐19 deaths in Italy


We don’t know, but it could be because:

  • of a secondary benefit of the flu vaccine in stimulating the immune system to help fight other diseases
  • people who get a flu vaccine might be more likely to go to a health care provider and so might in general be healthier than those who don’t
  • it’s just chance and is not actually related to getting a flu vaccine

Interestingly, the association has been found in more than one study.

“Specifically, we found that overall, a 10% increase in vaccination coverage was associated on average with a statistically significant 28% decrease in the COVID-19 death rate.”

Zanettini et al on Influenza Vaccination and COVID19 Mortality in the USA

And in multiple countries.

“Mortality was consistently lower among influenza vaccinated patients across all age groups, with absolute mortality differences ranging from a risk difference of 17% pts in the 10-19 age group to a risk difference of 3% pts in the 90+ age group.This difference was statistically significant (p-value < 0.05) for all age groups over 30.”

Fink et al on Inactivated trivalent influenza vaccine is associated with lower mortality among Covid-19 patients in Brazil

And it isn’t just the COVID-19 death rate.

“In the Italian population, the coverage rate of the influenza vaccination in people aged 65 and over is associated with a reduced spread and a less severe clinical expression of COVID-19.”

Amato et al on Relationship between Influenza Vaccination Coverage Rate and COVID-19 Outbreak: An Italian Ecological Study

Surprisingly, one study did report a positive association between COVID-19 deaths and influenza vaccination rates.

The study by a professor of forest genetics, forest ecosystem analysis, forestry, biometrics, forest growth, and biodiversity, “showed a positive association between COVID-19 deaths and IVR of people ≥65 years-old.”

That study is an outlier though…

“After reviewing the existing literature on the topic, we can safely conclude that influenza vaccination is unlikely to be associated with an increase in SARS-CoV-2 risk of infection or with COVID-19 severity and the risk of associated death. In fact, most reviewed studies detected an inverse relation, which was unexpected and even disconcerting given that influenza vaccines are not designed to protect from SARS-CoV-2. It must be acknowledged, however,that all reviewed studies are retrospective and observational in nature, thus likely to be not devoid of bias, which should warn against drawing premature conclusions regarding this finding. In conclusion, our review finds that based on our knowledge (up to the end of August 2020), public health measures aimed at raising the influenza vaccine coverage should be encouraged and there is no evidence to suggest that this would have a negative impact on populations in terms of SARS-CoV-2 related infections, illness or deaths.”

Del Riccio et al on The association between influenza vaccination and the risk of SARS-CoV-2 infection, severe illness, and death: a systematic review of the literature.

Most studies show a beneficial effect of getting vaccinated and protected with a flu vaccine.

And that’s another good reason to get a flu vaccine this year!

More on COVID-19 Deaths and Flu Vaccination Rates

1 thought on “What is the Association Between COVID-19 Deaths and Flu Vaccination Rates?”

  1. Pingback: 2021-22 Flu Season Predictions - Is This the Year of the Twindemic? - VAXOPEDIA

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