COVID-19 patients (28 studies with 212 acute and convalescent COVID-19 serum samples and with 462 convalescent plasma samples).
Evaluation of the frequency of viral RNA (vRNA) in blood, and to identify associated clinical characteristics, through a systematic literature review.
The included studies reported SARS-CoV-2 RNA in 0-76% of blood samples. Among the acute and convalescent COVID-19 serum samples, 27/212 (12.7%) had SARS-CoV-2 RNA detected by RT-PCR. RNA detection occurred in samples up to day 20 post symptom onset, and was associated with more severe disease. Across all samples collected ≥28 days post symptom onset, 0/494 (0%) had vRNA detected. Among the convalescent COVID-19 serum PCR-positive samples, cycle threshold values were high (range 33.5-44.8), suggesting low vRNA copy numbers. PCR-positive sera inoculated into cell culture did not produce any cytopathic effect or yield an increase in detectable SARS-CoV-2 RNA. There was a relationship between RT-PCR negativity and the presence of total SARS-CoV-2 antibody.