What Is the Inverse of a Superspreading Event?

At a superspreading event one infects many.

The inverse would be many infecting one.

And that is what seems to have happened in a prison in Vermont. The Wall Street Journal writes:

Federal health officials changed the definition of a close contact of a Covid-19 case, after a Vermont prison officer tested positive following several brief encounters with infected inmates.

The officer, a 20-year-old man, never was within 6 feet of any of the prisoners for 15 or more consecutive minutes, according to a report on the case by the U.S. Centers for Disease Control and Prevention and the Vermont Department of Health posted Wednesday.

After publishing the report online, the CDC altered its definition of a close contact, saying it is now someone who was within 6 feet of an infected person for a total of 15 minutes or more over a 24-hour period.

The previous definition was anyone who was within 6 feet of an infected person for at least 15 minutes.

“In the end, you just need to inhale enough virus, and there wasn’t any indication that they all need to be inhaled at the same time,” said Jose-Luis Jimenez, a professor of chemistry and aerosol scientist at the University of Colorado Boulder.

from CDC article about the case


Video surveillance footage showed the correctional officer’s limited contact with prisoners. The officer’s 22 interactions with the inmates totaled 17 minutes throughout an eight-hour shift, the CDC said.

The officer wore a mask, gown and eye protection during the encounters, the report said, though he sometimes didn’t wear gloves. But inmates didn’t wear masks during several encounters in a cell doorway or the recreation room.

Investigators weren’t able to determine the specific route of the officer’s infection, whether it was through droplets, aerosols or touching the same object as an infected inmate, said Patsy Kelso, the state epidemiologist for the Vermont Department of Health and an author of the report.

Dr. Kelso said investigators were confident the officer wasn’t exposed by an undetected case. The officer didn’t report any known exposures outside work, and the prevalence of Covid-19 in the local community was relatively low, the report said.

For more details, see the CDC article about the case.