Figure 1.

SARS‐CoV‐2 viral load dynamics at upper respiratory tract during COVID‐19. SARS‐CoV‐2 viral load at the upper respiratory tract varies largely during the course of COVID‐19, and peaks within about 4 days after symptom onset (or about 2 weeks after initial infection in asymptomatic cases). Symptomatic and asymptomatic individuals share similar viral load dynamics during the course of COVID‐19, which is divided into three phases, incubation/pre‐symptom, acute, and recovery phases. SARS‐CoV‐2 viral load is substantially lower during incubation/pre‐symptom and recovery phases than the acute phase, and transmissible SARS‐CoV‐2 virus persists from initial infection up to about 10 days after symptom onset or two to three weeks since initial infection in asymptomatic cases