- Dr. Bob
I Cannot Give You What I Do Not Have, But If I Have It, Do I Have To Share It?
A Discussion of Covid Transmission
A meta-analysis is a collection of studies that are similar in structure and methodology. It allows very powerful statistical analysis with larger numbers. The British Medical Journal has recently updated our knowledge on Covid SARS-2 with a meta-analysis that is interesting.
Many assume that a positive test means you have the disease. This is not necessarily true. Typically, a test is part of the evidence used to determine if someone has a disease, not the entirety of the evidence. A positive test with pathognomonic signs and symptoms is usually taken collectively as indicative of disease. Unfortunately, when it comes to Covid, there is large scale testing without clinical correlation to know if people are actually sick. The issue is further clouded by the fact that there is a difference between testing for viral fragments, or RNA, versus a live virus culture.
A person who tests positive for Covid may have recently acquired it and is not symptomatic yet. This may be a person who will never be symptomatic and will not transmit it. This may also be someone who never knew they had it at all and is on the tail end of the process. The true test would be a culture of live viruses, but no study has been able to culture live viruses and someone on the ninth day after the onset of symptoms. Presumably, this is why CDC allows asymptomatic healthcare workers to return to work after 10 days, as they are not symptomatic or contagious.
One question the meta-analysis sought to answer was whether asymptomatic people who test positive are contagious. In fact, it is unclear from research data whether asymptomatic people can be contagious at all.
A large study in the city of Wuhan, Ground Zero for the virus, looked at 10 million subjects without evidence of asymptomatic transmission. Other studies have suggested some asymptomatic transmission, but the consensus seems to be that it is very low. Of course, to the extent this is true, government mandated lockdowns are completely useless.
Another study published in the Journal of the American Medical Association found that about 18% of symptomatic patients are contagious, while asymptomatic people with positive Covid tests are contagious only at a rate of 0.7%.
The British Medical Journal published a report of 300 people who were Covid positive, but asymptomatic. Contact tracing revealed 1174 close contacts of these 300 people. There was not one case of transmission from asymptomatic study subject to a close contact.
Ultimately, we are all in hope that this whole thing is made moot with the increasing availability of vaccines. In the meantime, research gives hope that asymptomatic transmission is very rare if it happens at all.
So if you are asymptomatic, go to work, to church, or to Kroger with confidence. Stay away from sick people, though.