BIRMINGHAM, AL (WBRC) – In any given group of 25 people in Jefferson County, the risk at least one person has COVID-19 is 74-percent, according to the COVID-19 Event Risk Assessment Planning Tool.
The tool was created by Joshua Weitz and a team of scientists at the Georgia Institute of Technology.
“This is a collaborative effort done with researchers at Georgia Tech as well as colleagues locally and in California. The key idea is to try to communicate the risks associated with gatherings,” explained Weitz, Professor, School of Biological Sciences.
He added, “We developed this tool in early July and the idea was to try to relate recent COVID case reports and associate that with the probability, the risk that someone in a crowd, particularly as the crowd gets to be 25, 50 or 100 that someone might have COVID.”
The calculations are made factoring in “under-testing” and using data from departments of public health collected by The New York Times and The COVID Tracking Project.
“The CDC has gone back and looked and compared using antibody tests that tests for whether a person had the virus rather than if they had it now and found there may be as many as 10 times or more cases that have occurred for each documented case,” said Weitz when explaining the formula used.
Weitz said the tool can be used to help determine the risk of students returning to school.
“If a school district is starting online [this estimate] helps reinforce why that’s justified and even as community transmission gets lower, we are trying to prevent new cases from spreading,” said Weitz.
In Jefferson County, the risk of a person having COVID-19 in a group of 25 is 74-percent, according to this tool. The risk increases to 93-percent with the group size doubles. In a group of 500, the risk of someone having COVID-19 is greater than 99-percent.
“What I would say is, do you know as an administrator of the school, if folks coming into the building are COVID free? And the answer is you don’t know unless you are testing and given background circulating levels, you should anticipate that people will be showing up to school infected and that one or two cases may soon become many.”
He said Alabama is not in a good position to reopen schools without mitigation plans, like “100-percent mask compliance.”