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Researchers are constantly trying to refine their understanding of the coronavirus pandemic in order to make meaningful recommendations and accurate predictions. To help with this, they have a suite of mathematical models that, for example, can predict the impact that interventions like social distancing, universal mask-wearing, or stay-at-home orders will have on the trajectory of the pandemic.
However, as anyone who has ever tried to analyze data knows, the best model in the world is useless if it's fed inaccurate data. This is captured by an acronym that dates back at least to 1963, GIGO--garbage in, garbage out.
Probably the most garbage-laden information about the COVID-19 pandemic is the actual number of people in a given region who have been infected by the SARS-CoV-2 virus. This number is necessary in order to calculate how infectious the virus really is, how quickly it can spread through a population, what proportion of the population remains vulnerable, and, crucially, how deadly it is.
Unfortunately, in the absence of widespread testing and contact tracing, typically only severe cases get confirmed and counted. The trick is to get a handle on how many uncounted cases there are for each confirmed one.
That's the key number which is now providing us both good and bad news.
The bad news is that multiple signs point to there being many more people who have been or are currently infected than the official, confirmed case counts tell us. That's bad because it means that you're much more likely to run into someone carrying and potentially shedding the virus than you and public health authorities probably thought.
The good news is that if there are in fact many more COVID-19 cases than we thought, but if the count of deaths is reasonably accurate, then the virus may be significantly less lethal than we thought in terms of the number people who die compared to the total number who catch the virus.
Here are some relevant data points:
--Out of 3,330 people tested for antibodies to the SARS-CoV-2 virus in Santa Clara County, California, 1.5 percent tested positive. That doesn't sound like much, but it implies that the actual number of cases in that county is 50 to 85 times greater than the confirmed case count.
--A similar study in Los Angeles County found an infection rate between 2.8 and 5.6 percent among adults. Compared to the 8,000 confirmed cases at that time, it implies a true incidence of infections between 27.5 and 55 times greater than the official count.
--New York State has turned out to be the unfortunate epicenter for the virus, with more than 288,000 confirmed cases and more than 22,000 deaths to date. When 3,000 people in 19 counties were tested for antibodies, 13.9 percent tested positive (and a remarkable 21.2 percent in New York City). Those numbers indicate that there have been at least 10 undocumented cases in the state for every confirmed case.
The picture is still blurry--we need much more testing, not only to make the models and their predictions more accurate, but, along with contact tracing and effective isolation, to be able to get our lives and the economy back to normal.
Critics tell us that the above numbers must be scrutinized with care. Statisticians point out that when the incidence of a disease is low, a less-than-perfect test can produce enough false positives to significantly blur the picture. Others point out that it is hard to match these indicators of a more widespread but milder and much less lethal illness with well-documented clusters of cases and fatalities, as we saw on several cruise ships.
Still, if we squint, it looks as though there are probably ten times or more actual cases of COVID-19 than confirmed cases.
So again, when you go out, someone comes to your door or you find yourself among a group of people, anyone you're close to is 10 times more likely to be contagious than you might have thought.
But that also implies that the SARS-CoV-2 virus may well be ten times less lethal than we've been told so far; it may kill just two out of a thousand cases rather than the more frequently cited estimates of from 7 to 34 out of a thousand. From the point of view of the population as a whole, that's definitely good news.
However, if you, like 92 million other Americans, are over 65 or have an underlying medical condition such as hypertension, diabetes or obesity, you remain at high risk of serious illness or a miserable death from the virus. For those at high risk, the crucial, and potentially vital take-away is the fact that there may be 10 times more potential sources of contagion outside your door than you thought.
Please take care!
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| What are your chances of finding yourself in a situation like this? Credit: U.S. Air Force/Staff Sgt. Kevin Linuma |
Probably the most garbage-laden information about the COVID-19 pandemic is the actual number of people in a given region who have been infected by the SARS-CoV-2 virus. This number is necessary in order to calculate how infectious the virus really is, how quickly it can spread through a population, what proportion of the population remains vulnerable, and, crucially, how deadly it is.
Unfortunately, in the absence of widespread testing and contact tracing, typically only severe cases get confirmed and counted. The trick is to get a handle on how many uncounted cases there are for each confirmed one.
That's the key number which is now providing us both good and bad news.
The bad news is that multiple signs point to there being many more people who have been or are currently infected than the official, confirmed case counts tell us. That's bad because it means that you're much more likely to run into someone carrying and potentially shedding the virus than you and public health authorities probably thought.
The good news is that if there are in fact many more COVID-19 cases than we thought, but if the count of deaths is reasonably accurate, then the virus may be significantly less lethal than we thought in terms of the number people who die compared to the total number who catch the virus.
Here are some relevant data points:
--Out of 3,330 people tested for antibodies to the SARS-CoV-2 virus in Santa Clara County, California, 1.5 percent tested positive. That doesn't sound like much, but it implies that the actual number of cases in that county is 50 to 85 times greater than the confirmed case count.
--A similar study in Los Angeles County found an infection rate between 2.8 and 5.6 percent among adults. Compared to the 8,000 confirmed cases at that time, it implies a true incidence of infections between 27.5 and 55 times greater than the official count.
--New York State has turned out to be the unfortunate epicenter for the virus, with more than 288,000 confirmed cases and more than 22,000 deaths to date. When 3,000 people in 19 counties were tested for antibodies, 13.9 percent tested positive (and a remarkable 21.2 percent in New York City). Those numbers indicate that there have been at least 10 undocumented cases in the state for every confirmed case.
The picture is still blurry--we need much more testing, not only to make the models and their predictions more accurate, but, along with contact tracing and effective isolation, to be able to get our lives and the economy back to normal.
Critics tell us that the above numbers must be scrutinized with care. Statisticians point out that when the incidence of a disease is low, a less-than-perfect test can produce enough false positives to significantly blur the picture. Others point out that it is hard to match these indicators of a more widespread but milder and much less lethal illness with well-documented clusters of cases and fatalities, as we saw on several cruise ships.
Still, if we squint, it looks as though there are probably ten times or more actual cases of COVID-19 than confirmed cases.
So again, when you go out, someone comes to your door or you find yourself among a group of people, anyone you're close to is 10 times more likely to be contagious than you might have thought.
But that also implies that the SARS-CoV-2 virus may well be ten times less lethal than we've been told so far; it may kill just two out of a thousand cases rather than the more frequently cited estimates of from 7 to 34 out of a thousand. From the point of view of the population as a whole, that's definitely good news.
However, if you, like 92 million other Americans, are over 65 or have an underlying medical condition such as hypertension, diabetes or obesity, you remain at high risk of serious illness or a miserable death from the virus. For those at high risk, the crucial, and potentially vital take-away is the fact that there may be 10 times more potential sources of contagion outside your door than you thought.
Please take care!
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