Higher viral load associated with COVID-19 transmission risk
Higher viral loads of SARS-CoV-2, the virus that causes COVID-19, are associated with an increased risk of transmission, according to cohort study results from Catalonia, Spain, published yesterday in
The
Lancet Infectious Diseases,
Researchers found that the overall secondary attack rate was 16.6%, although they ranged from 12% when the index case had a viral load lower than 1·10
6 copies per milliliter (mL) to 24% when viral load was 1·10
10 copies per mL or higher.
Viral loads are not a set value, but previous research has shown they peak around the time of symptom onset, notes a related commentary by Laura Cornelissen, MD, and Emmanuel André, MD, PhD, two Belgian infectious disease experts.