An investigation conducted by Vermont Department of Health scientists and released last week by the Centers for Disease Control and Prevention (CDC) found that transmission of the coronavirus can occur during multiple brief exposures with someone who is infected.
According to a news release, staff from the Health Department and the Department of Corrections looked into an instance in which a state correctional officer became infected after several brief interactions with incarcerated people who had COVID-19. None of the individual interactions lasted 15 minutes but over time, they exceeded that duration.
CDC officials cited the investigation findings in announcing its updated definition of what is considered to be a “close contact.” The Vermont report was published in the Oct. 21 issue of CDC's Morbidity and Mortality Weekly Report.
The CDC definition now defines a close contact as someone who was within 6 feet of an infected person for a cumulative total of 15 minutes or more over a 24-hour period. This is a refinement of previous guidance, which defined close contact as being within 6 feet, for 15 minutes or more at a time.
The Vermont investigation team reviewed video surveillance footage to determine that the correctional officer did engage in close contact as it had been defined.
The team reviewed additional footage and standard correctional officer shift duty responsibilities to approximate the frequency and duration of interactions between the officer and infectious people at the facility.
Health Commissioner Mark Levine said on Oct. 22 that he is proud of his team's work and pleased the CDC is taking this data into account, to increase understanding about the importance of maintaining physical distance.
“Throughout the pandemic, we have let the science lead the way,” said Levine in a news release.
An author on the study, state Public Health Veterinarian Natalie Kwit, noted that the key finding - that the correctional officer did not initially meet the definition of a close contact - will help public health officials better identify people who could be at risk for getting and spreading the coronavirus.
“Vermont is already doing this to a certain degree, but all public health officials can consider this research when doing contact tracing and interviews,” Kwit said. “It may be more relevant in certain group and congregate settings, where there is potential to have these multiple brief interactions.”
Kwit emphasized that identifying a close contact is about more than just the length of time of an exposure. How far away a person is, whether they are symptomatic, and the environment are all factors that need to be considered.
“It may expand the number of close contacts identified in certain situations, but it also serves as a reminder of how important it is for people to do the best they can to avoid possible exposure,” said Kwit. “We all know the key things to do: wear a mask and stay physically distant. But, especially as we start to spend more time indoors, it's important to avoid crowds and large gatherings whenever possible.”
This new understanding of the illness will affect reopening plans for some institutions, including schools.
“We are discussing the implications of this information as well as the updated 'Strong and Healthy Start' document from the Agency of Education in our planning for the remainder of this semester as well as the second semester,” said Windham Southeast Supervisory Union Superintendent Andrew Skarzynski in an email to The Commons on Tuesday.
“This information will be considered with multiple additional factors in our conversations and planning,” he said.
The Vermont study can be found at bit.ly/585_vtstudy.