As vaccinations against the SARS CoV-2 virus ramp up, perhaps more slowly than they should, the goal of herd immunity seems to be in reach. But its explanation since last Fall has not necessarily cleared up its confusion. So, tonight, the Perpetual Notion Machine has invited Ajay Sethi, an epidemiologist and Associate Professor in Population Health Sciences at UW-Madison, to help clear up the confusion. In his discussion with PNM’s Dennis Shaffer, Ajay points out that if enough people in a community have immunity, then the spread of an infectious disease and the outbreaks of infection will be significantly reduced, or maybe even eliminated. However, a highly contagious virus like COVID-19 requires a high amount of immunity, mostly through vaccinations, in order to achieve this result. In other words, there is a threshold, or R0 point, between those immune, ie. those vaccinated, and those not yet immune. Ajay says that we don’t know this point. But we do know that as more people get vaccinated, the number of COVID cases and deaths have dropped at lot. But also, for those not vaccinated or immune, this is NOT a signal to stop wearing masks and congregating in crowds. Ajay reminds us that COVID will not go away completely, just as a new variant has been reported in Vietnam.

Here are some links to more information:

Badger Talks video on herd immunity

Johns Hopkins Public Health on herd immunity

The Mayo Clinic’s definition of herd immunity

And a New York Times article by Apoorva Mandavilli on whether herd immunity can be reached. Apoorva was a past volunteer on PNM.

Featured Image courtesy: AJC1 at Flickr.com