Frequently Asked Questions about COVID-19 — November 16, 2022

“Shared expectations lead to predictability.”

599. Rapid changes in research and science have created public health confusion.

         Q:  Why is guidance about what to do to prevent getting Covid-19 so confusing?

         A:  In an opinion article in last Sunday’s Hartford Courant, two epidemiologists at the University of Connecticut School of Medicine were quoted as saying, “Over the past two years of the Covid-19 pandemic, the recommendations from the US Centers for Disease Control and Prevention (CDC) have changed frequently.  These changes have resulted in 60% of Americans feeling ‘confused,’ and 56% feeling less confident in public health officials’ recommendations as a result.”  Hank Weinstock, MPH, and David Banach, MD, MPH recommend that the CDC should consider measuring wastewater for the presence of the Covid-19 virus as the more reliable method of surveillance.

It is true that the CDC has changed its guidance over the course of the disease.  An example is the traditional public health measure of calculating the positive rate of Covid tests given to predict the risk of future infections in a given population.  The World Health Organization had established an international standard that if a given number of tests given daily shows an increasing percentage of positive tests reaching 5%, restrictive measures such as masking should be imposed.  And then science developed the take-home testing capability.  Over the past year, tens of thousands of people using these tests found they were positive and sought medical care.  None of these home test results were centrally recorded, so a positive test ratio could not be determined.  The more reliable PCR laboratory tests were given, but not to everyone.  So, the percent positive of these tests was not useful as an assessment of risk.  The positive test ratio disappeared.

One of the new CDC guidelines that replaced it was to evaluate how the number of Covid-19 patients filled local hospital bed capacity.  The authors correctly point out that this measure is heavily influenced by the larger number of beds in major medical centers instead of the concentration of Covid patients in the adjacent communities.

The recommendation they offer – surveillance of wastewater to assess risk – suffers from similar characteristics, the complexity of the disease and the technology that surrounds it.  While measuring wastewater is a valid measure of future risk in communities that have centralized wastewater management, this cannot become a national CDC standard for everyone.  It would not be feasible to periodically sample and evaluate wastewater in thousands of individual septic tanks.

The conflict appears to remain with us, at least for a while – the need for simple answers to complex problems as defined by improving technology.