Contact tracing, masking and vaccines are vital, says lead author Yang Ge, a doctoral student in UGA’s College of Public Health.
“We found asymptomatic cases had lower transmissibility compared to symptomatic cases and were less likely to infect their contacts. In addition, we found that contacts that developed COVID-19 infections were more likely to be asymptomatic if they were exposed to an asymptomatic case,” said Ge.
“This suggests interventions like vaccines and masking should continue to be encouraged.”
Vaccines protect the vaccinated individual, and also work to suppress the amount of virus that close contacts could be exposed to, and masking reduces the spread of aerosolized particles that could contain the virus.
This is a large cohort study done on 730 individuals who received a COVID-19 diagnosis in Zhejiang Province, China, between Jan. 8, 2020, and July 30, 2020.
Detailed health records and contact tracing were used. The team was able to apply state-of-the-art analytical approaches to determine how the timing of exposure and disease severity impacted the risk of transmission.
The cohort included 8,852 close contacts- members of a household, coworkers, and those exposed in a health care setting or shared transit.
Though Shen says that these results need to be repeated in vaccinated populations, the study identifies a high-risk transmission window to help local municipal and public health officials target contact tracing efforts.
The study was co-authored by researchers at UGA, Boston University School of Public Health, Zhejiang Provincial Center for Disease Control and Prevention, University of Texas School of Public Health, and Tulane University School of Public Health and Tropical Medicine.