“Those findings are now in bold, italics and underlined,” said Jay C. Butler, the CDC deputy director for infectious diseases and a co-author of the study published in the journal JAMA Network Open.
As disease specialists had forecast for months, the coronavirus is spreading with speed and ferocity in the new year, with Thursday’s single-day record for deaths underscoring the threat. In the past seven days, U.S. infections, hospitalizations and deaths have hit record highs. Cases reached a record 277,135 on Saturday. And by Thursday, more than 132,000 people were hospitalized in the nation with covid-19, the disease caused by the virus.
With more than 363,000 Americans dead since the start of the pandemic, the CDC’s most recent forecast predicts fatalities could stand between 405,000 and 438,000 by the end of January.
There is no evidence that the surge is being driven by the more contagious strain, known as B117, because if it were, it would have turned up in more of the genomic sequences analyzed by researchers in recent weeks. But health officials fear the variant could make a bad situation worse, driving more patients into hospitals and boosting the covid-19 death toll.
On Thursday, three states — Connecticut, Pennsylvania and Texas — reported detecting B117, joining California, Colorado, Florida, Georgia and New York. Health experts have said they believe the virus variant may be present throughout much of the country. The variant is not believed to carry a greater risk of illness or death for individual patients. But experts have been alarmed at the likelihood it is more transmissible, which could result in more people developing covid-19 and, in turn, more deaths overall.
“We are in a race against time,” said Jennifer Nuzzo, an epidemiologist with the Johns Hopkins Center for Health Security. “We need to increase our speed in which we act so that we don’t allow this virus to spread further and allow this variant to become the dominant one in circulation. The clock is ticking.”
The need to slow transmission is especially evident in Los Angeles County, where Public Health Director Barbara Ferrer said Wednesday the region was in the midst of “a health crisis of epic proportions.” The county has reported more than 200 daily covid-19 deaths in recent days and has about 8,000 people hospitalized with covid-19. Statewide, California reported 583 deaths Thursday.
Describing herself as “more troubled than ever before,” Ferrer reiterated pleas for residents to follow public health guidance to try to slow the spread and ease the strain on hospitals.
“In Los Angeles County, we have doubled the number of people passing away each day, and this reality has upended all aspects of our health-care delivery system,” Ferrer said. “Our tragedy continues until we get it together to change our actions.”
At Methodist Hospital in Arcadia, northeast of downtown Los Angeles, administrators announced they had adopted crisis care guidelines. According to state guidelines, a hospital is at crisis care level when resources are scarce and the focus shifts to delivering the best care possible under the circumstances, forcing choices that may pose risk to patients.
Three other hospitals have notified the California Department of Public Health that they are approaching or entering that stage, which triggers the mobilization of regional and state resources to better care for patients. The agency did not identify the other three.
Methodist Hospital officials said they had activated a triage team, which includes doctors, community members, a bioethics specialist and spiritual care providers, to “make the difficult, but necessary decisions about allocating limited resources.”
Clifford R. Daniels, a senior vice president and chief strategy officer at the hospital, stressed that care had not been rationed as of Thursday and that all patients are receiving the care they need.
“We hope to never get there,” Daniels said. “It truly is the antithesis of every doctor and nurse in their training to deny care to somebody. We never want to be there. It almost makes me emotional to think in metropolitan Los Angeles in the 20th century that’s something that might happen.”
Administrators have had to redirect resources to accommodate 111 covid-19 patients, including 30 in intensive care, Daniels said. Some who are on ventilators are not in the ICU, where they would normally be treated, and instead are on other wards. Staffing is the biggest concern, he said; the hospital is paying nurses three times its normal rate and “looking at nooks and crannies” to try to find more.
The National Guard has provided five medics and a supervising nurse, Daniels said, while the state sent several more after the hospital moved to crisis care. Hospital officials believe the impact of Christmas and New Year’s Eve gatherings has yet to be realized, he said, and they’re bracing for a growing surge.
“If the demand for hospital services continues at the pace that it’s at now,” he said, “I fear that we may be facing a situation that was once unimaginable.”
The research the CDC released Thursday on how the coronavirus is spread comports with earlier estimates of the contribution of asymptomatic spread.
“It’s certainly confirmatory, but it’s nice to see confirmation,” said epidemiologist Richard Menzies, who directs the McGill International TB Centre in Canada and was not affiliated with this research. “These are pretty believable, solid results.”
Fifty-nine percent of all transmission came from people without symptoms, under the model’s baseline scenario. That includes 35 percent of new cases from people who infect others before they show symptoms and 24 percent that come from people who never develop symptoms at all.
Many factors influence how the coronavirus spreads. The researchers took an admittedly uncomplicated approach — Butler called it “a fairly simple mathematical model” — and used that to assess several scenarios, varying the infectious period and the proportion of transmission from people who never develop symptoms.
The model consistently predicted asymptomatic spread accounted for roughly half of viral transmission. But Muge Cevik, an infectious-disease expert at Scotland’s University of St. Andrews, argued some of the model’s assumptions are flawed.
Cevik also noted the study does not account for the environment where the spread occurs.
“Maybe asymptomatic transmission is important, but it may be much more important in long-term care facilities and households,” Cevik said. “That might mean that we need to do much more targeted testing for high-risk populations,” as opposed to mass screening.
Whether vaccines stop coronavirus transmission is not yet certain, and was not a scenario addressed in this model. “The data on the impact of the vaccines on asymptomatic infection are very limited,” Butler said, though he anticipates more information in coming months.
The clinical trials for two vaccines authorized by U.S. regulators in December concluded the vaccinations are highly capable of preventing symptomatic illness. But those trials did not determine whether vaccinated people are still able to spread the pathogen.
“If they were asymptomatic but equally contagious, then that’s going to have quite an impact on the epidemic,” Menzies warned.
As of Thursday, more than 21 million doses of coronavirus vaccine had been distributed to states, and just under 6 million had been administered, according to CDC data.
National Institutes of Health Director Francis S. Collins acknowledged in an interview with The Washington Post this week that U.S. distribution got off to a “rocky beginning” but said he was “not totally surprised by that.”
“The next couple of weeks are going to be really critical to see how we can get this distribution system up and going more smoothly,” Collins said.