When will we reach herd immunity in Alabama?

Published: Mar. 4, 2021 at 6:57 PM CST
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BIRMINGHAM, Ala. (WBRC) - As more vaccines are being added to the market, there is more talk of when we’ll possibly reach herd immunity. It’s what we’ll need to reach before things start getting back to whatever normal will look like after the pandemic. We’re looking deeper into when we could reach herd immunity in Alabama

“It’s not a magical number,” says UAB epidemiologist Dr. Suzanne Judd. “Each virus, each bacteria is different and they mutate at regular intervals so this number can move…but at the moment, scientists are shooting for about 72% of the population with immunity,” Dr. Judd said.

Dr. Judd says we could reach herd immunity by late spring. Alabama has 4.9 million people. To reach that 72%, 3.53 million of us will need to be immune one way or another.

That may be easier than you think. It’s based on the number of shots already into arms and a new study from Columbia University showing that more people had COVID-19 than were tested. In some cases, a 5 to 1 ratio and others 10 to 1 meaning 10 people had the virus but did not have a positive test but still have immunity to COVID.

The Columbia study suggests that at the end of January, more than a third of the U.S. population had already been infected with COVID-19. Judd says the numbers will still need to be studied more, but she’s hopeful.

“The more people that have immunity, the less the virus will spread. The safer it will be for us to interact with one another again,” Judd said.

Several factors play into reaching herd immunity like the rate of vaccination. We know getting shots in arms in Alabama is speeding up; no longer the snail’s pace of a few months ago. Another factor is the emerging variants especially the one from the U.K. Something else to watch for is the R0 number or “R-Naught” which measures how many times the virus is spreading from person to person.

“That needs to get down to less than one. We are still certainly at a time where our percent positive in the state is high, our numbers of cases are still high,” Dr. Karen Landers with the Alabama Department of Public Health said.

Landers says there will not be a specific day that we all of sudden say we’re at herd immunity. We asked her if the May time frame is even realistic?

“I want to be cautious about where we could be over the next few months. We don’t know how long natural immunity lasts after COVID disease so while it’s a very good model, we want to continue to see numbers of cases go down. We want to see hospitalizations go down,” Landers said.

The nation’s leading health expert Dr. Anthony Fauci hopes children will be vaccinated by spring or summer. That’s another key to achieving herd immunity. Tests are underway to see if the age requirements for the vaccine can come down.

You can read more about herd immunity from UAB at

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