The confusing COVID-19

WHO’s latest viewpoint is that the asymptomatic very rarely disseminate COVID-19 (https://www.yahoo.com/news/says-rare-asymptomatic-people-spread-220300316.html).  This is after months, often considered settled science, that the asymptomatic are important carriers for COVID-19 transmission.  It may rank as high as the much maligned statement by the Chinese experts on Jan 14, 2020 (my June 2, 2020 blog) in terms of sowing confusion in the public.  Ironically, both were based on available data at the time, hence, completely defensible, while the confusion lies in how to interpret the data and statements.  Since the Jan 14 statement has been dissected thoroughly, the WHO statement is analyzed here.

First the paramount notion of asymptomatic must be understood, which seems simple but is not.  Most people are asymptomatic, because most don’t have COVID-19.  So merely saying asymptomatic is meaningless.  Thus, perhaps “asymptomatic” means RNA positive but asymptomatic?  This is the most widely accepted definition, and includes two classes: 1. Pre-symptomatic, who exhibits no symptoms at the time of RNA test but gets sick later, and 2. The true asymptomatic, who never gets sick.  Admittedly, whether one feels or reports sick is somewhat subjective, but that Class 1 are and will become infectious is not in dispute.  Whether and how much Class 2 are infectious, though, remains unclear, not the least because how to define them is subjective.  Note that asymptomatic infection is not unique to COVID-19.  HBV, HIV, and many viruses can have asymptomatic infections and transmission for years.

As my 6/6/ blog explains, though, this definition can change or expand based on a better understanding of COVID-19.  How about Class 3: perhaps infected many weeks or months ago, still RNA positive today but asymptomatic?  Some recovered COVID-19 patients are like this.  No evidence these people are infectious.  Moreover, last week Wuhan finished RNA testing 10 million people and found a total of 300 asymptomatic.  From the samples of these 300 people, no live virus was recovered by culturing.  And none of their close contacts tested RNA positive.  This > 100 million US dollars experiment tells us Class 3 is not transmitting.  

And there are people, never tested before, but now known to be negative RNA, positive IgG, and asymptomatic.  Clearly they don't spread the virus today, but the real question is before.  My 6/6/2020 blog suggests that it overlaps with the recovered patients but also may include a new Class 4 of people who, despite getting the virus, never became infected, and, hence, were never carriers.  Either they would not have tested RNA positive, or if they did, the RNA reflected dead virus.  This is because for whatever reason, e.g., their immune system was able to eliminate the virus quickly, COVID-19 never took hold in their bodies.  Class 4 could be the silent majority: based on Ab test data 1-10% of the population in quite a few countries or cities are Ab+, much higher than the RNA test positive.  

Of course at this moment we don’t know for sure how big Class 4 is.  Ab test is imprecise.  But looking at these 4 classes, what WHO said is certainly plausible.  Just that nobody should get easy.  How can one tell who is a true asymptomatic (Classes 2-4) or pre-symptomatic (Class 1)?  Especially asymptomatic is often self-reported, at least at first.  

   

One thing from the WHO statement, though, is that perhaps the scary factor of COVID-19 is further reduced.  The person we see or meet in public is not likely going to give you the virus.   >99% he is not infected.  Or he is asymptomatic with a low viral count.  And you practice social distancing.   

Of course, a lot about COVID-19 remain confusing.  Its transmission, asymptomatic or not, was hotly debated since Jan 2020.  Another topic that has stayed even more opaque is treatment (4/28/20 blog).  Drugs like (hydroxy)chloroquine, remdesivir, Kevzara, and others.  While much about COVID-19 diagnosis, symptoms, and care was quickly established in China by late Feb and well confirmed around the world since then, little progress has been made, up until now, mid June 2020, to identify a good drug.  Chloroquine is likely not useful.  Remdesivir may help a bit, but not the miracle drug so many people had hope for.  People may still be able to develop a new drug, just not from the existing batch.

Humans’ best bet is vaccine.  Again, there are a wide range of vaccine types, vaccine companies, and clinical trial status.  Even if successful, much is unknown about how soon everybody can get it and how long the vaccines can provide immunity.  Don’t be surprised to see continuous and more confusion into 2021.  

Note: WHO quickly clarified the claim (https://www.yahoo.com/lifestyle/who-walks-back-statement-very-rare-asymptomatic-spread-infectious-disease-experts-not-accurate-193933330.html), although how much asymtomactic transmission occurs remains uncertain to anybody.  It very much depends on your definition of "asymtomactic".  Interestingly, the report quoted Dr. Megan Ranney as saying: “More accurate would be to say: It is difficult to determine what degree of transmission is due to asymptomatic spread.”  This is what we get after > 5 months' intensive learning, and everybody is so forgiving.  By the same criterion, on Jan 14, 2020, it was entirely more accurate to say: It is difficult to determine what degree of transmission is due to human to human.  One has to wonder why it got so much bad press, and 6 days later it changed anyway.