Covid-19’s spread in China might tell us how deadly Omicron really is

Covid-19’s rapid spread in China has prompted reports of crowded hospitals and inundated crematoria. It could also help answer whether Omicron is truly a milder version of the virus.

Iterations of the Omicron variant are spreading rapidly in China after officials relaxed zero-Covid controls in place for most of the pandemic. Pharmacies say they are out of fever medications and hospitals are strained, employees have said. Chinese officials have reported a modest rise in Covid-19 cases and deaths, but some public-health experts and relatives of the deceased suspect a higher toll.

Chinese officials have told citizens that Omicron is significantly less deadly than previous variants. Some studies suggest Omicron is milder than earlier versions. In countries including the U.S., high levels of Omicron-fueled infections are translating into less severe disease compared with earlier waves.

But Covid-19 vaccines and prior infections have bolstered immune defenses in the U.S. and elsewhere, public-health experts said, lowering risks of hospitalization and death as the pandemic goes on.

China is meeting the Omicron variant with less exposure to the virus and lower vaccination rates among the elderly, public-health experts said. Covid-19’s spread there will help explain to what extent lower rates of severe disease and death are influenced by Omicron’s nature compared with a population’s built-up defenses.

“China will be very important for us in understanding how Omicron works,” said Dr. Melanie Ott, who directs the Gladstone Institute of Virology at the University of California, San Francisco.

Tracking Omicron’s impact in China will be a challenge because undercounted deaths could obscure its deadliness and blind residents to the full danger, public-health experts said. They, along with relatives of deceased patients, have said they think the government isn’t publicizing the full toll from the virus.

China has reported a handful of deaths since it ended its control policies. Its definition for what constitutes a Covid-19 death is narrow by global standards.

China leaned on measures including mass testing, lockdowns and border closures to contain the virus and limit case numbers for most of the pandemic. Covid-19 vaccination drives and work to strengthen health infrastructure to prepare for surges weren’t as much of a focus.

Now China, with the rest of the world, is confrontingthe rapid spread of Omicron subvariants. Shortly after Omicron was identified in late 2021, and quickly outcompeted other virus versions, some studies and anecdotal reports from doctors indicated it caused milder disease than its predecessor, Delta. But it was significantly more transmissible.

Research in human cells and animals such as hamsters has suggested that Omicron might not infiltrate as deeply into the lungs as its predecessors, potentially leading to less severe disease. Instead, there might be a heavier impact on the upper airways, said Michael Diamond, a viral immunologist and professor of medicine at the Washington University School of Medicine in St. Louis.

“That’s why you might get more transmission and less severe disease,” Dr. Diamond said, an author on one such paper. He also said that the animal findings might not apply to people.

Researchers in the U.S. found that among hospitalized patients without prior immunity, the risk of severe outcomes was lower among patients infected with Omicron compared with people infected by Delta. But the risk from Omicron among hospitalized patients was similar to that of earlier variants including the original strain, according to the study published in Clinical Infectious Diseases this month.

Omicron is still probably less severe overall than earlier versions of the virus, said Matt Robinson, lead author on the paper, and assistant professor in the Division of Infectious Diseases at Johns Hopkins University School of Medicine. Dr. Robinson said increases in population immunity in the U.S. and other places have helped boost protection against severe illness.

Virus levels in U.S. wastewater show higher readings nationally than two years ago, when deaths in the nation peaked, data from tracking company Biobot Analytics show. But mortality has dropped. States and territories reported about 2,950 Covid-19 deaths in the most recently measured week, according to the Centers for Disease Control and Prevention, compared with a peak topping 23,380 in a single week in January 2021.

The U.S. reported about 2,700 Covid-19 deaths in the most recently measured week, according to the Centers for Disease Control and Prevention, compared with a peak of 26,000 in a single week in January 2021.

Omicron’s ability to spread so easily can still lead to a significant death toll, even if individuals face lower risks. The variant in the U.S. last winter triggered the second-highest level of deaths in the pandemic, in part because of the sheer number of people infected. Covid-19 ranked as the third-leading U.S. cause of death after heart disease and cancer in both 2020 and 2021.

Most of China’s population has gotten at least one vaccine dose, but only 66% of people 80 and older are fully vaccinated and just over 40% had received a booster shot, an official with China’s National Administration of Disease Control and Prevention said last week. China has said it was aiming to get at least 90% of people 80 and older at least one shot by the end of January.

In Hong Kong, which also had tight pandemic controls and low vaccination and booster rates among older people, Omicron spread widely earlier this year. At its peak the death rate was among the highest recorded globally during the pandemic.

“There is great concern that the Hong Kong experience will be reflected across China as a whole,” said Dr. Christopher Chiu, a professor of infectious diseases at Imperial College London.

(This story has been published from a wire agency feed without modifications to the text.)