What makes some one a COVID-19 super-spreader?

Tulane researchers help narrow it down and trace the origin of the initial 2020 Mardi Gras outbreak
Updated: Feb. 10, 2021 at 9:55 PM CST
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NEW ORLEANS (WVUE) - Researchers at Tulane University have contributed to two significant COVID-19 super-spreader studies and have started to narrow down how the virus is transmitted.

“There’s not a lot of solid stuff around how this disease is transmitted,” Dr. Chad Roy said.

We know COVID is airborne, but after studying almost 200 people researchers from Tulane and several other universities suggest people who are older with a higher body mass index breathe out more respiratory droplets with the virus.

“20 percent of that group that was sampled accounted for 80 percent of the total aerosols that are breathed out and so that’s kind of this idea of a super spreader profile,” Roy said.

Dr. Chad Roy with Tulane’s National Primate Research Center found in two species of primates that respiratory particles of the virus increase as time goes on, even in asymptomatic cases, peaking around seven days after infection. He says they also get smaller which means easier to breathe in.

“It really reinforces this idea of prevention, because now we’re kind of understanding the biological basis of airborne transmission,” Roy said.

It quite possibly was just one person and their droplets that was the spark in a super-spreading Mardi Gras powder keg last year.

“The virus probably came in around February the 11th, you know of course, Mardi Gras day was February 25, and then by March 9, we were detecting the first case,” Dr. Robert Garry said.

Another study Tulane was a part of gene sequenced 200 viruses. It also looked at cell phone and travel records and suggests the virus was brought in by one person.

“The most likely point that the virus entered Louisiana was from Texas, but you know, it could have been from any of the surrounding states, really,” Garry said.

Researchers, like Dr. Robert Garry at Tulane, created a family tree of those virus cases and found most of the cases in New Orleans were related to each other.

“If you look at the COVID-19 outbreaks in other cities, you see that they typically got quite a few different introductions, dozens, actually,” Garry said. “So, as far as different strains lineages of the virus in New Orleans, it was pretty much just that one early on.”

Just one strain, but at a perfect time for the virus. People crowded together, laughing, dancing, singing... blissfully unaware.

“Unfortunately, canceling the parades and some of the activities was the right thing to do this year,” Garry said. “These are exactly the type of events that we know spread SARS CoV-2.”

That study also suggests that the virus strain in New Orleans infected other parts of Louisiana, Mississippi, Texas and Alabama. However, stay-at-home restrictions and limited air travel appear to have kept it from spreading to other regions of the country.

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