When Is a Person With COVID-19 Most Infectious?

By Robert Preidt
HealthDay Reporter

FRIDAY, Aug. 27, 2021 (HealthDay News) -- New probe delivers an reply to a burning question: When are COVID-19 patients astir infectious?

The answer? Two days earlier and 3 days aft they make symptoms.

The findings item the value of accelerated investigating and quarantine if idiosyncratic is feeling sick, the survey authors said.

The researchers besides recovered that infected radical are much apt to beryllium asymptomatic if they caught the microorganism from a superior lawsuit (the archetypal infected idiosyncratic successful an outbreak) who was besides asymptomatic.

"In erstwhile studies, viral load has been utilized arsenic an indirect measurement of transmission," said survey co-leader Dr. Leonardo Martinez, an adjunct prof of epidemiology astatine Boston University's School of Public Health.

"We wanted to spot if results from these past studies, which amusement that COVID cases are astir transmissible a fewer days earlier and aft grounds onset, could beryllium confirmed by looking astatine secondary cases among adjacent contacts," Martinez said successful a assemblage quality release.

For the study, Martinez and his colleagues analyzed information from astir 9,000 adjacent contacts of superior cases successful the Zhejiang state of China from January 2020 to August 2020. That's earlier the advent of the adjacent much contagious Delta variant.

Close contacts included radical who lived successful the aforesaid household oregon who dined together, co-workers, radical successful infirmary settings and riders successful shared vehicles. They were monitored for astatine slightest 90 days aft their archetypal affirmative COVID-19 trial results.

Of the superior cases, 89% developed mild oregon mean symptoms, 11% were asymptomatic, and nary had terrible symptoms.

Household contacts of superior cases and radical who were exposed to superior cases aggregate times oregon for longer amounts of clip had higher corruption rates than different adjacent contacts, the findings showed.

But each adjacent contacts were much apt to beryllium infected by the superior lawsuit if they were exposed soon earlier oregon aft that idiosyncratic developed symptoms, according to the survey published online Aug. 23 successful JAMA Internal Medicine.

In examination to mild and mean symptomatic superior cases, those who were asymptomatic were overmuch little apt to infect adjacent contacts. If they did, the contacts were besides little apt to person noticeable symptoms, the researchers reported.

Continued

"Our results suggest that the timing of vulnerability comparative to primary-case symptoms is important for transmission, and this knowing provides further grounds that accelerated investigating and quarantine aft idiosyncratic is feeling sick is simply a captious measurement to power the epidemic," Martinez said. "This survey further emphasizes the request for vaccination, which reduces objective severity among radical that make COVID."

More information

The U.S. Centers for Disease Control and Prevention has much connected COVID-19.

SOURCE: Boston University School of Medicine, quality release, Aug. 26, 2021