(Santa Barbara, Calif.) — In July, after weeks of steady but relatively slow increases in COVID-19 infection rates in Santa Barbara County, the number of cases per day began a steep climb, setting records with alarming frequency. By month’s end, the cumulative number of new cases had about doubled.



UC Santa Barbara researchers detected early signs of that surge, and in a population where the SARS-CoV-2 virus is largely invisible, but still potent: asymptomatic carriers. In the research for a paper currently published in pre-print form on MedRxiv, biologists Carolina Arias and colleagues got an unusual glimpse of how COVID-19 can travel silently through a community.



“Asymptomatic individuals are those with positive results who never develop symptoms,” said Arias, who led the study. Because they never feel sick, she explained, they could unknowingly transmit the virus to others as they circulate in the community. The same applies to presymptomatic individuals — those who do not have symptoms at the time of the test, but develop them later. The Center for Disease Control’s current best estimate predicts that 40% of COVID-19 infections occur via people who show no symptoms.



CONTACT:

Sonia Fernandez

(805) 893-4765

sonia.fernandez@ucsb.edu

Shelly Leachman

(805) 893-8726

shelly.leachman@ucsb.edu