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Saturday, November 14, 2026Nov 14

Tennessee’s low COVID-19 vaccination rate makes herd immunity less attainable; here’s why that matters

FILE - In this Friday, March 19, 2021 file photo medical staff members administer the AstraZeneca vaccine at La Nuvola (The Cloud) convention center that was temporarily turned into a COVID-19 vaccination hub, in Rome. AstraZeneca said Monday March 22, 2021 that advanced trial data from a U.S. study on its COVID vaccine shows it is 79% effective. The U.S. study comprised 30,000 volunteers, 20,000 of whom were given the vaccine while the rest got dummy shots. (AP Photo/Gregorio Borgia)
FILE - In this Friday, March 19, 2021 file photo medical staff members administer the AstraZeneca vaccine at La Nuvola (The Cloud) convention center that was temporarily turned into a COVID-19 vaccination hub, in Rome. AstraZeneca said Monday March 22, 2021 that advanced trial data from a U.S. study on its COVID vaccine shows it is 79% effective. The U.S. study comprised 30,000 volunteers, 20,000 of whom were given the vaccine while the rest got dummy shots. (AP Photo/Gregorio Borgia)

Tennessee’s low COVID-19 vaccination rate threatens more than just those who choose not to get vaccinated, which is why the health care and scientific communities are pushing for more education and efforts to combat vaccine hesitancy in order to get more shots into arms.

“My grave concern is that if people don’t appreciate the continued toll that this pandemic is taking on our country, and they don’t recognize the benefits of vaccination, our ability to get to that state of so-called ‘herd immunity’ is uncertain,” infectious disease specialist Dr. Jay Sizemore said during an Erlanger Health System Board of Trustees meeting Thursday.

“Herd immunity” occurs when a large enough portion of the population is immune to an infectious disease that it provides indirect protection to others who aren’t immune. That’s because circulation of the disease grinds to a halt when there aren’t enough susceptible people left to infect.

Immunity can be achieved through vaccination or prior infection. However, vaccination is always preferred. Vaccines prevent more death, illness and opportunity for the disease to spread, and herd immunity for a disease has never been achieved without a vaccine.

The threshold for herd immunity differs by disease and depends on how infectious it is. Measles, one of the most contagious diseases in the world, requires about 95% of a population to be vaccinated, while the threshold for polio is about 80%, according to the World Health Organization.