On the opening night of this conference, a discussion of “how we got here” recounted a week of discussions and swiftly escalating events surrounding the spread of COVID-19 that got us here, at the first online version of the Conference on Retroviruses and Opportunistic Infections.
Today that discussion took a longer view, across a history of coronavirus cross-species transmission dating from 500 to 800 years back, to the acceleration in the 21st century of known events that have included outbreaks of SARS, MERS, SADS-CoV (Swine Acute Diarrhea Syndrome — a diarrheal disease that crossed from pigs to humans) and now SARS-CoV2, the virus that causes COVID-19, to the first cases of illness reported in China, its response, and the international spread that followed. It was a discussion that also looked ahead — to the large known reservoir of other coronaviruses, “poised” as epidemiologist Ralph Baric explained it, for trans-species spread, and to the responses, including research toward expanded knowledge and diagnostics as well as the first promising moves toward treatments and vaccines against the virus.
Dr. Zunyou Wu of the Chinese Center for Disease Control and Prevention recounted the now familiar but still dizzying sequence of events in China over the last three and half months:
- a Dec. 27 report that a new coronavirus posed a threat; a Dec. 31 public health alert;
- the isolation of 1.4 billion people in their homes for 10 days and the cordoning off of 59.2 million people in Hubei province that continues;
- the addition of more than 48,000 hospital beds;
- the deployment of 40,000 health care workers;
- the graphs showing the steep drop of cases from the end of January;
- and the conclusion that a million cases of illness were averted by ancient public health measures.
He reviewed the questions that were answered in those fast-moving weeks:
- That in China, at least the majority of cases resulted from close contact with symptomatic people;
- That among those infected the mean time from when they were exposed to the virus to when they experienced symptoms ranged from five to six days;
- That infection without the development of symptoms appears to be rare — with less than 1 % of patients diagnosed but never reporting symptoms;
- But that patients could “shed” — and transmit — the virus one to two days before experiencing symptoms of illness
- That patients with mild illness — an estimated 80 percent of patients — recovered in two weeks, and patients with severe illness who did recover doing so so within three to six weeks.
Transmission in closed settings, including prisons and nursing homes hadn’t appeared to be a major driver, he said, although how that had been determined is unclear, and no transmission had been seen in schools — although, he noted, early on they had all been closed.
Since March 4th, Dr. John Brooks of the United States Centers for Disease Control and Prevention said, deaths due COVID-19 outside of China have exceeded the numbers of those dying from the disease in China. While estimates of the percentage of COVID-19 cases that lead to death is likely to drop as more people with mild illness are diagnosed, with a likely case fatality rate of from 0.5 to 3.5, the coronavirus is from five to 35 times more deadly than seasonal flu. And while WHO officials continue to emphasize containing the spread of disease over mitigating its impacts, while calling the two approaches a “false dichotomy,” U.S. communities experiencing outbreaks, Dr. Brooks said, have moved from focusing on known cases to preparing for more.
While animal markets have been associated with the amplification of coronavirus spread from animals to humans, and hospitals have served as epicenters for disease expansion, epidemiologist Ralph Baric of the University of North Carolina said, community spread of SARS-CoV2 is now understood as common, due to its relatively long incubation and prevalence of mild cases of illness compared to previous coronaviruses.
His institution, one of five testing the antiviral drug remdesivir as a treatment for COVID-19, is one of many looking for answers. As of the last week, the WHO International Clinical Trials registry records 261 new studies of approaches to understanding, diagnosing and treating COVID-19 Dr. Anthony Fauci of the National Institute of Allergy and Infectious Diseases said in the last presentation today. More funding opportunities — to identify vaccine candidates, animal models, medical responses — are on the horizon, he said. “It’s a rapidly evolving field.”
CROI has made the session on COVID-19 publicly available.
Jaclyn Levy, director of science and research policy for the Infectious Diseases Society of America, contributed to this report.