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Equal amounts of virus in asymptomatic and sick COVID-19 Patients: JAMANETWORK

EM of SARS-COV-2 from Groopman lab

This study used 303 people who were placed in isolation due to a positive RT-PCR SARS-COV-2 test but few symptoms in South Korea (the Republic of Korea.) Some 36% of them had no symptoms at the time they were isolated; of these 36%, only 19% went on to develop symptoms– meaning about 29% of the people with positive tests never developed symptoms. The study used quantitative testing to discover how much virus each person shed in their nasopharyngeal and lower respiratory secretions (snot and sputum) and found that, on average, people with and without symptoms produced the same amounts of virus. This suggests that asymptomatic people are equally likely to be infectious to others and should be isolated as well (which we would be doing, if we got the test results in time.)

Here’s the findings and discussion from the abstract:

Findings  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.

These people were relatively young (median age, 25) and two-thirds were women. It took about six days on average to get a person into the quarantine dormitory after making a diagnosis; the location was specially selected to hold those with few or no symptoms. For this reason, the virus amounts described are not typical for patients with severe symptoms.

The symptoms consisted mainly of cough and runny nose (about half of patients for each) with sputum in 28%, followed by sore throat (a quarter), loss of smell, upset stomach, and diarrhea (less than 10% each.) Only one patient was transferred to hospital– for severe vomiting.

On average, those who didn’t develop symptoms at first took 15 days to become symptomatic. One-third of asymptomatic people cleared in two weeks, and three-quarters cleared after three weeks. Patients who had symptoms or developed them cleared in about 30% of cases after two weeks and 70% after three weeks.

The median time to clearing was 17 days in asymptomatic people and 19.5 days in symptomatic (including presymptomatic) patients. It’s important to note that a positive test doesn’t equate to shedding of infectious virus. The study looked at three parts of the virus genome and found that not all parts were detectable in low-positive tests, suggesting that the virus genome was broken up in those cases.

The study suggests that people without symptoms are probably equally likely to transmit infection when they expose others as are patients with symptoms. The authors recommend that asymptomatic people should be isolated too in order to prevent spread of the infection.

The duration of quarantine that best prevents spread is unknown– initially two weeks from onset of symptoms was recommended, but recently that has been reduced to ten days. For someone with no symptoms, there is no clear time, although it’s probably less than for sick people. There is no clear division, and positive tests with highly sensitive assays like the RT-PCR don’t mean someone is still infectious.

Unfortunately, a news story from Santa Clara County, California says that test results are taking as long as 16 days to be returned– rendering them useless from an infection control point of view. We don’t have any way to control the spread of infection by isolating people in this country unless we dramatically improve testing capacity and turnaround time.

The drastic isolation measures that were taken in South Korea are impossible here, in part because so many people are testing positive now, and in part because it takes so long to get the results. A strategy of rapidly producing tests, especially those that give immediate results, would have been a big help. It’s too late now.

It appears that a vaccine, rapidly produced and rapidly administered to everyone, is the only hope to control the spread of COVID-19 in this country. Will there be a national will to accept a vaccine? I don’t think so. Too many people are too selfish and unscientific.

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