In his research paper, published online Thursday by the journal Health Affairs, Basu acknowledges there’s still lots of uncertainty surrounding the fatality rate for the disease caused by the coronavirus known as SARS-CoV-2. But he says there’s evidence that the U.S. death toll could amount to 350,000 to 1.2 million.
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Anirban Basu is the Stergachis Family Endowed Director of the CHOICE Institute at the University of Washington’s School of Pharmacy. (UW Photo)
“This is a staggering number, which can only be brought down with sound public health measures,” Basu said in an interview with MedicalResearch.com.
The latest projections from UW’s Institute for Health Metrics and Evaluation estimate that the U.S. death toll due to COVID-19 will amount to nearly 135,000 by Aug. 4. IHME’s projections are closely watched (and occasionally lowballed) by the White House. “We’ll be at 100,000” or 110,000 deaths, President Donald Trump told Fox News today.
Unlike IHME’s projections, Basu’s calculations don’t depend directly on what kinds of social distancing policies are in place, and they’re not limited to the time frame between now and August. They’re based purely on estimates of how many people who contract the disease end up dying.
Based on an analysis of figures from 116 counties selected from 33 states, Basu estimates that the symptomatic infection fatality rate, or IFR, is 1.3%. That figure has an uncertainty interval of 0.6% to 2.1% at 95% confidence.
Running the numbers on fatalities
To derive his “staggering” death toll, Basu assumes that 20% of the U.S. population is infected with the virus by the end of the year, and that more than 80% of those people show symptoms. The others would never know they had the virus.
Running the percentages on the upper and lower limits of the uncertainty interval would give you 350,000 to 1.2 million deaths, if you start with a high estimate for U.S. population.
Basu admits that his assumptions may not be quite right. That’s particularly true for the assumptions relating to how many people with the virus never show symptoms. “Population-wide antibody testing would be needed to establish this statistic,” he says in the Health Affairs research paper.
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But at least some of the assumptions are well in line with what other researchers are finding. “This agrees with our model’s 0.9-1.2% IFR [infection fatality rate] estimate from last week,” Youyang Gu, a data scientist who’s in charge of a COVID-19 projection model that’s often compared with IHME’s model, wrote in a tweet.
Eric Topol, founder and director of the Scripps Research Translational Institute, said Basu seemed to be on the right track with his estimate of the fatality rate. “I think that it’s a very fair estimate given it’s still unknown, a work in progress we’ll nail down better over time,” Topol told GeekWire in an email.
For what it’s worth, Basu’s symptomatic infection fatality rate estimate for Seattle and the rest of King County is higher than the norm, at 3.6%. But he points out that the figures can vary depending on the demographics of the COVID-19 patient population and the care they receive.
“It is possible, as the infection spreads to more rural counties of the country, the overall IFR will increase due to the lack of access to necessary health care delivery,” he said.
Bad news about virus transmission
Another concern has to do with what happens when social distancing policies are relaxed. The Bellevue, Wash.-based Institute for Disease Modeling had some bad news for western Washington state on that score today.
After weeks of seeing declines in the transmissibility of COVID-19, epidemiologists reported that the data showed a slight uptick as of April 22. The institute’s analysis suggests that the outbreak is plateauing, or potentially on its way to a rebound, with 95% of King County’s population still fully susceptible to COVID-19.
“This report once again reminds us that our position is precarious and COVID-19 transmission and new cases remain unacceptably high,” Jeff Duchin, health officer for Public Health – Seattle & King County, said in a news release.
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The black dots represent the most recent estimates of the effective reproductive number in King County from the Institute for Disease Modeling, with lines extending above and below the dots representing error bars. The gray dots show the previous estimates for comparison. Recent data points suggest that the transmissibility trend is edging back upward after a long decline. (IDM Graphic)
“We need to double down on distancing and other prevention steps at home, in the community and in workplaces, and we must see these numbers improve before relaxing our current restrictions,” Duchin said.
Looking on the bright side, it’s possible that the prospects for surviving the virus will improve due to the development of new treatments. Or that the chances of contracting the virus in the first place will decrease when vaccines become available.
“All these estimates are based on the fact that right now there’s no treatment or vaccine,” Basu told GeekWire.
When we look back at all this a year from now, let’s hope that the outlook for the outbreak isn’t staggering, but encouraging.
More from GeekWire:
- Univ. of Washington researchers predict 80,000 COVID-19 deaths in U.S. by July
- Coronavirus modelers raise projected U.S. death toll and lengthen state-by-state recovery timeline
- Scientists create atomic-scale map of coronavirus’ deadly weapon, pointing out a path to fighting it
- Is the outbreak widening or fading? Fresh analysis suggests that we’re ‘on the cusp’
