Data glitch muddies case trends
The rate of new coronavirus cases in California appears to be plateauing, a Bay Area infectious disease expert said Wednesday, although a major technical problem affecting the electronic data system used by state and local health departments has cast doubt on the accuracy of some numbers.
“As you look through the big contributors to this, they all have very similar trends. That’s one of the things that I think makes me some
what more confident that the trends are real,” George Rutherford, professor of epidemiology and biostatistics and principal investigator of California’s contact tracing program at UCSF, said at a news briefing.
Citing monitoring of cases by cities and counties, coronavirusrelated hospitalizations and the number of beds open in intensivecare units, Rutherford said new infections in the state do seem to be leveling off. Those categories are not affected by the data reporting issues.
The glitch with the state electronic case reporting system, known as CalREDIE, short for the California Reportable Disease Information Exchange, has led to questions about whether the state is undercounting coronavirus cases. The state’s top health official, Dr. Mark Ghaly, said the problem may have contributed to what initially appeared to be a 21% decline in the number of coronavirus tests that were coming back positive, a figure Gov. Gavin Newsom cited Monday as reason for cautious optimism.
Other health experts said that given the data reporting problems, it was difficult to tell how well the state is doing. Santa Clara County’s public health director, Dr. Sara Cody, said at a separate news conference Wednesday, “It’s not just inconvenient. This lack of data means we don’t know where the epidemic is heading, how it’s growing or not.”
Cody added, “I would say that right now, we’re back to feeling blind.”
The state has not said when the problem began or how far back the data are compromised, but Cody said it may be affecting case counts as far back as midJuly.
“We expect all of our numbers will go up,” she said. “To what extent, we don’t know.”
Cody noted, however, that hospitalization numbers have been dropping in Santa Clara County, which is an encouraging and more reliable sign that the outbreak is slowing.
The data collection problems don’t affect just the county’s ability to identify trends, Cody added. Public health officials rely on the state case reports to do contact tracing, a key component of containing new infections and preventing further spread of disease.
The state’s reporting of new cases, one of the metrics affected by the datareporting problem, continued to indicate a sharp drop Wednesday. The rolling 14day average was listed as 7,939 per day, 14.6% lower than a week ago.
Rutherford, however, said that the reliable data show that the state’s reimposition of shutdowns of several business sectors is helping stem the spread of the virus. There are still problem areas, including parts of Southern California, the Central Valley and cities such as Salinas and Ventura that are near farmland, with large numbers of agricultural workers.
“The epidemic is moving from urban Latino populations to rural Latino populations,” Rutherford said.
Summertime travelers are also spreading the virus to places that had largely been spared, including the Mammoth Lakes area on the eastern side of the Sierra and Lassen County in northeastern California, Rutherford said. Lassen is also being hit by outbreaks in state and federal prisons in the county.
Rutherford said California is a long way from being in the clear. Children returning to classrooms in some parts of the state, plus the second reopening of public life as cases decline, will test the state’s ability to keep the virus in check.
“We’ll see it go back down a little bit before it goes back up again,” he said. “I think that part is just inevitable.”
Ultimately, Rutherford added, “this is not going to be controlled without a vaccine. Make no mistake about it.”
Rutherford was joined for the hourlong briefing by UCSF colleague Joel Ernst, an expert on infectious diseases and vaccine development. Ernst offered a rundown on the six most promising vaccine trials, and said the earliest a vaccine might be available is July 2021.
He said predictions by Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, that a vaccine would be ready before the end of the year are “optimistic.” Having a vaccine go through all the phases of development and safety testing by this time next year would be impressive, Ernst said.
“This is lightning speed compared to traditional vaccine development,” he said.