New Reporting Suggests Many Positive Coronavirus Cases May Not Be Contagious
Reporting by the New York Times last week highlighted a possible answer to the unique presentation of the coronavirus in human subjects.
Since March, most governmental steps have largely been based on the believed ever-present threat of asymptomatic spread of the virus. Information pouring in from across the globe during the rapidly developing situation created a bevy of responses to fears that were later alleviated or amended.
Americans stopped washing their groceries, landscapers were allowed to work and new evidence may suggest that pervasive asymptomatic spread may be next in line to be cooled by better evidence and understanding of the threats posed by covid-19.
Fears of asymptomatic spread in Germany began after an article was published and later retracted in the New England Journal of Medicine that highlighted spread from a Chinese visitor to the country. It later came to light that researchers had not spoken to the Chinese visitor directly regarding whether she had been experiencing symptoms. She had. The Germans interviewed by the researchers commented that they did not think she had been and the foundation for one of the greatest elements of our response was seeded: contagious asymptomatic spread.
This possibility was particularly frightening and caused states and nations across the globe to test with far greater sensitivity than would be the case with other viruses. It also spurred governmental orders for mandatory universal masking, self-quarantine, social distancing, school closures, statewide lockdowns and many other measures which have largely diverged from traditional viral mediation techniques; primarily, vaccinate & stay home if you are sick.
Instead, widespread belief that the virus could be carried unbeknownst to an individual, while still being contagious, has led to some of the most unique responses in modern history.
We’ve been using one type of data for everything, and that is just plus or minus — that’s all. We’re using that for clinical diagnostics, for public health, for policy decision-making. It’s really irresponsible, I think, to forgo the recognition that this is a quantitative issue.”Dr. Michael Mina, Epidemiologist, Harvard T.H. Chan School of Public Health, New York Times
However, new reporting supports what some critics have been clamoring about since the spring, namely that PCR testing (the testing method responsible for the lion’s share of tests run in the U.S. and around the globe) has utilized a far greater sensitivity and lower viral threshold for diagnosing a positive test than may be useful for determining public policy.
French Epidemiologist Didier Raoult remarked last spring (further reading) that he believed an appropriate threshold of 33 was necessary to detect the virus at contagious levels. Instead, many states have opted for far more sensitive thresholds of 37 to 40. That may not seem like much to a layman, but in practice, these differences in sensitivity skew the number of active and even contagious cases by 40 to a staggering 90%.
In other words, if a state registered 100 positives tests, as little as 10 may be currently active or contagious level infections depending on that state’s chosen testing threshold. Though his assertions were dismissed nearly 6 months ago and his support for hydroxychloroquine became controversial as the Trump administration began to publicly support hopes of the drug being used in treatment, the tide seems to be turning his way.
These findings may explain several phenomenon surrounding our early speculation regarding the virus. First, it may suggest an answer to the question of why this virus appeared peculiarly unique in its ability to linger in the body and deliver positive tests weeks to even months after symptoms had subsided in some or never arrived in many others.
This may be a reason to take other recent news coverage of outbreaks on college campuses with a grain of salt as well. The assumption has been that these outbreaks stemmed from students’ return to campus after just a single week at college, but may in fact be casting a clearer picture of community infection from a month or more before kids returned to school.
In short, the tests may be so sensitive that they pick up trace amounts of the virus, even when subjects are neither sick, nor actually contagious. Furthermore, subjects may not be asymptomatic in spite of the virus, but because of such low viral loads that symptoms and contagious levels never develop. Thus, it may be that the long perceived uniqueness of Covid-19 is more of a feature than a bug, resulting from the way governments and public health officials have approached, tested and handled it from the onset.
In the case of other viruses, viral loads must be present in significant amounts to return a positive test. Positive tests in those cases often overlap very strongly with contagious levels of the given virus. It has been widely assumed, as witnessed in the measures undertaken by states across the country, that a positive Covid-19 test should be understood to mean that a person is contagious.
Protocols have recommended that the positive individual and those they have recently come in close contact with for 15-minutes or more should self-isolate for 14 days.
These elements of coronavirus response have, in turn, continued to drive fears of an invisible contagion, hitchhiking without symptoms in some and attacking with deadly brutality in others. While these presumptions have underscored the nationwide coronavirus response since the spring and “15 days to slow the spread” turned to 6 months of lockdowns, shutdowns, social distancing, masking and more, that mentality may be changing.
In an interview with the New York Times, Dr. Michael Mina, an epidemiologist at the Harvard T.H. Chan School of Public Health, explained, “We’ve been using one type of data for everything, and that is just plus or minus — that’s all. We’re using that for clinical diagnostics, for public health, for policy decision-making.” Dr. Mina continued by explaining that a yes or no is insufficient given the sensitivity of our PCR testing for coronavirus and suggests that the viral load is far more important than our response has suggested. “It’s really irresponsible, I think, to forgo the recognition that this is a quantitative issue.”
These findings come on the heels of information released from the CDC that details just a 6% rate of covid-19 fatality death certificates listing covid-19 singularly under cause of death and an average of an additional 2.6 underlying causes of death among the other 94% of cases. While many cases certainly developed additional comorbidities as a result of covid-19 infections, specifically pneumonia, the average of 2.6 additional causes of death per case and a median fatality age in line with normal United States life expectancy at 78 years old, data is increasingly supporting the belief that the virus poses far less risk of fatal infection to those without significant health issues or of an advanced age.
While some critics may see this as justification for their long-held skepticism, these trends appear to be a positive swing in our understanding of the virus and that is something we should all welcome.