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Achieving herd immunity is a tall order

It is clear that nationally, those determined to have nothing to do with the COVID vaccine may actually prevent us from achieving herd immunity nationally in a reasonable time frame. Do we have any estimates of how herd immunity may or may not be established in Oregon?

— Robert P., Medford

The SYA news team reached out to our local experts on all matters COVID-19-related for this one, and Jackson County Medical Director Dr. Jim Shames came through with some precise figures concerning the question and zero speculation concerning the statement.

Achieving herd immunity, he explained, relates to the infectivity of the disease in question. Measles, for instance, is an extremely contagious disease and therefore requires nearly 95% of the population to be vaccinated to achieve herd immunity and prevent community spread.

That magical percentage of the population that must be immune to a disease to stop its spread, he explains, is called the “herd immunity threshold.”

When COVID-19 first started spreading around the globe, the herd immunity threshold was determined to be about 70% — that is, the percentage of people immune either through vaccination or illness.

“However,” Shames said in an email, “as the disease has continued to spread, variants have developed, some of which have a higher herd immunity threshold, and therefore with the variants now dominant, the herd immunity threshold for COVID-19 is felt to be somewhere between 80% and 85%.”

Shames admits that’s a tall order, but he noted that the higher the vaccination percentage, the safer we’ll be in general. The latest numbers in Oregon suggest we have a long way to go. According to the Oregon Health Authority, as of Thursday 42.9% of Oregonians had been vaccinated – 30% were fully vaccinated and 12.9% had begun their vaccination series. In Jackson County, 36.1% were vaccinated, 24.9% fully.

“Getting 85% of all the citizens in Oregon to accept a vaccination, not to mention many children who are not yet eligible, will be a very heavy lift indeed,” Shames said. “However, the closer we get to that herd immunity threshold, whether we get 60% or 70% vaccinated, the less COVID will spread in our community. More is better, so let’s encourage everyone to get vaccinated.”

Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; or by email to youasked@rosebudmedia.com. We’re sorry, but the volume of questions received prevents us from answering all of them.