Seoul – Asymptomatic carriers of Sars-CoV-2 have as much virus in their respiratory tracts as symptomatic carriers, according to a study published in JAMA.
And there seems to be no valid reason why asymptomatic people can’t transmit the virus. In fact, the study authors said it maybe necessary to isolate asymptomatic carriers to protect the public.
The South Korean researchers set up the study in March with one basic question – “Are there viral load differences between asymptomatic and symptomatic patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection?”
“In this cohort study that included 303 patients with SARS-CoV-2 infection isolated in a community treatment center in the Republic of Korea, 110 (36.3%) were asymptomatic at the time of isolation and 21 of these (19.1%) developed symptoms during isolation.
“The cycle threshold values of reverse transcription–polymerase chain reaction for SARS-CoV-2 in asymptomatic patients were similar to those in symptomatic patients.”
“Meaning Many individuals with SARS-CoV-2 infection remained asymptomatic for a prolonged period, and viral load was similar to that in symptomatic patients; therefore, isolation of infected persons should be performed regardless of symptoms.”
The study is important because it disrupts the idea that asymptomatic people do not transmit or that they produce fake results in swab tests.
Many jurisdictions test asymptomatic people – for example Alberta – and find positive cases. Other jurisdictions like BC do not test asymptomatic people unless they are part of a cluster of disease outbreak.
“303 symptomatic and asymptomatic patients with SARS-CoV-2 infection between March 6 and March 26, 2020. Participants were isolated in a community treatment center in Cheonan, Republic of Korea.”
“Of the 303 patients with SARS-CoV-2 infection, the median (interquartile range) age was 25 (22-36) years, and 201 (66.3%) were women.
“Only 12 (3.9%) patients had comorbidities (10 had hypertension, 1 had cancer, and 1 had asthma). Among the 303 patients with SARS-CoV-2 infection, 193 (63.7%) were symptomatic at the time of isolation.
“Of the 110 (36.3%) asymptomatic patients, 21 (19.1%) developed symptoms during isolation. The interval of time from detection of SARS-CoV-2 to symptom onset in presymptomatic patients was 15 (13-20) days.”
“The proportions of participants with a negative conversion at day 14 and day 21 from diagnosis were 33.7% and 75.2%, respectively, in asymptomatic patients and 29.6% and 69.9%, respectively, in symptomatic patients (including presymptomatic patients).
“The median (SE) time from diagnosis to the first negative conversion was 17 (1.07) days for asymptomatic patients and 19.5 (0.63) days for symptomatic (including presymptomatic) patients.”
“In this cohort study of symptomatic and asymptomatic patients with SARS-CoV-2 infection who were isolated in a community treatment center in Cheonan, Republic of Korea, the Ct values in asymptomatic patients were similar to those in symptomatic patients.
“Isolation of asymptomatic patients may be necessary to control the spread of SARS-CoV-2.”
But obviously they must be found first. Scientists have suggested asymptomatic people can be stealth spreaders driving the pandemic.