Slowing the spread, getting herd immunity just got a lot harder

Like many in his stead, infectious disease physician Dr Sajal Tanna is doing his best to keep pace with the Delta Wave. This is a sign that collective immunity to COVID-19 is becoming increasingly out of reach.

“The number of herd immunity depends on the ease of transmission of the virus,” Tanna said.

Delta is a different beast – more contagious. It boils down to R-naught, a number that shows how contagious a virus is.

“For every person who gets sick, how many people are they likely to infect,” said Jason Farley, nurse epidemiologist trained in infectious diseases at Johns Hopkins University. “We thought it was around 1.5 to two to three, according to estimates.”

In other words, an infected person, on average, has made two to three other people sick. But now with Delta:

“We are seeing it again this R-draw of five, six, six plus,” he said.

This means that slowing the spread and gaining herd immunity have become much more difficult.

Another way to put it: think infectious disease on a contagious scale with Delta. It’s about two steps away from measles and pertussis. For measles, experts say 95% of people need herd immunity vaccines.

“If we mean by herd immunity, there will be no COVID in your community. It may require 90, 95%, a number that we probably can’t reach until we start immunizing children,” he said. said Dr. Bob Wachter, Department of Medicine at the University of California, San Francisco.

Every expert Newsy spoke to across the country – the East Coast, the Midwest, the West Coast – shared the serious concern: In this race for the variant vaccines, we are late. In parts of the country where rates are higher, that means not completely overwhelming hospital emergencies and COVID units.

“You are currently witnessing a much more intense struggle in states like Florida or Louisiana, because they are far from being immune to collective immunity. The population is not protected.

And that is why we are seeing such a massive increase. The big concern is the spillover effect. With modern travel, it’s easy for one part of the country to share things with another, ”said Dr. Nicholas Turner, assistant professor of infectious diseases at Duke University Medical Center.

In other words, Delta means a big step backwards, with every weak spot causing the further spread of COVID.

“If we don’t get this virus under control and get ahead of it, we’ll talk about the need for not just boosters, but maybe even different vaccines to move forward,” Farley said.

That doesn’t mean, however, that Delta is making COVID vaccines unnecessary. These snaps could mean the difference between a visit like this and one in the COVID ICU.

“We are seeing an increase in COVID infections in the two unvaccinated vaccinated people. The difference is, the unvaccinated patients I see are so much sicker.

Having a breakthrough infection is always really miserable, but I don’t see these people in the hospital, and I don’t see them on life support, ”Tanna said.

Lindsey Theis of Newsy first reported this story.