Why are COVID-19 cases rising in the US at the same time deaths are dropping?

Every source I have looked at over the past two weeks has suggested an interesting phenomenon: COVID-19 cases are increasing while deaths are dropping dramatically. I include the figures from tonight’s Apple news spotlight, however the numbers from the New York Times, Johns Hopkins University, and multiple other sources including the CDC also indicate identical trends. 

One can hypothesize several reasons why this is occurring. One might be that the increase in case numbers is coming simply from increased testing and documentation of infections. Another might be that people who are infected are not dying at the same rate because they are healthier or their care has improved. Finally, it may be that the virus has changed so the infection is less severe and less likely to cause fatalities. 

I believe there could be a combination of these factors, and I will address them in likelihood of their relative contributions.

The one thing I don’t believe has happened is that the virus has changed or mutated in a way that has made it less lethal. While this claim was made by a physician in Italy, there is no data suggesting that this has happened. I addressed the D614G viral substitution yesterday. I can only say that there is no evidence that a new, less lethal strain of coronavirus has evolved.    

There is some chance that care for individuals with COVID-19 has improved. Better means of preventing individuals from requiring mechanical ventilation (ventilators), remdesivir the antiviral drug, and several of the anti-inflammatory therapies may have improved care. But only remdesivir has reached general use for COVID-19 infected individuals, and the ability to prevent mortality in clinical trials with this drug was minimal.  

Importantly, even if deaths were being prevented with therapy, hospital utilizations should still continue to increase. While there have been anecdotal reports of this in certain areas of Florida and Texas, the overall numbers for both the United States and these states in particular do not show increased hospital utilization (IHME data, shown below). 

Therefore, we are left with two alternatives: that fewer, healthier people are being infected or the majority of the increase in cases that we’re seeing are due to increased testing or differences in reporting. There have been reports that infections in younger people have increased tremendously. In reviewing the CDC website, however, the rates of coronavirus infection, have not changed. 

Dr. Tom Frieden, former director of the US Centers for Disease Control and Prevention, wrote in a Twitter post that there was an increase in infections of young people, but quoted no data. When he spoke on CNN, he only mentioned anecdotal data. Therefore, there is no firm data that excess infections in younger, healthier people are the reason deaths are dropping.

The only reasonable conclusion left is that we are identifying more infections, especially those that are asymptomatic (the majority) by testing more frequently, using better tests, and making rational assignments of infection based on retrospective data (antibody tests that show infection after the fact). This is best shown in the University of Washington Institute of Health Metric Analyses numbers where the only factor is increasing reports of testing. Combining viral testing and antibody testing to give overall infection numbers has made reporting difficult to evaluate.

We should be applauded because we are doing a better job of testing and reporting COVID-19 infections. Let’s hope this trend continues while deaths continue to fall.