According to a meta-analysis of COVID research published in The Lancet, individuals with COVID are most infectious early on.
In a meta-analysis of 79 studies from around the world, they examined viral load dynamics, duration of viral RNA shedding, and viable virus shedding for SARS-CoV-2, and for comparison, 8 studies on MERS-CoV and 11 on SARS-CoV. The study only looked at symptomatic individuals.
For SARS-CoV-2, the average duration of viral RNA shedding was 17 days in the upper respiratory tract and 14.6 days in the lower respiratory tract. Similar durations were found for stool (17.2 days) and serum samples (16.6 days).
The maximum duration of viral RNA shedding was 83 days in the upper respiratory tract, 59 days in the lower respiratory tract and 126 days in stools. No role could be discerned for faecal shedding. Average shedding duration was positively correlated with age. No studies detected live virus after 9 days.
The viral load in the upper respiratory tract reached a peak in the first week of illness, which was shorter than SARS-CoV (peaking at days 10-14) and MERS-CoV (days 7-10). Most studies indicated faster viral load clearing in asymptomatic versus symptomatic SARS-CoV-2 carriers.
In view of these findings, the researchers suggest that repeat testing may not be necessary for patients no longer deemed infectious, and that isolation could be set for 10 days after the onset of symptoms.
The researchers concluded that early containment was key in fighting the spread of COVID, especially with regard to acting on atypical symptoms that might appear before other symptoms. Still, this could prove challenging to effect in practice.
Source: The Lancet
