Chinese scientists say coronavirus illness symptoms peaked on February 1 - but they warn that the epidemic could 'rebound'

• A study of more than 72,000 coronavirus patients in China found that the largest number of patients were showing symptoms on February 1.
• That could be a sign that the outbreak is tapering off.
• But the authors also warned that the outbreak could rebound once Chinese residents return to school and work.
• For the latest case total and death toll, see Business Insider's live updates here.
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With each passing day, China continues to report more cases of the deadly coronavirus that emerged in the city of Wuhan in December.

COVID-19, as the illness is now known, has so far infected more than 73,000 people and killed at least 1,875.

But a recent study of more than 72,000 patients in China suggests that coronavirus illnesses may have peaked in early February.

The study authors, who work at the Chinese Center for Disease Control and Prevention (China CDC), examined cases of the virus from December 8 to February 11. Their results showed that the largest number of coronavirus patients started exhibiting symptoms on February 1.

Since then, there haven't been as many new illnesses, the authors found. That could be a sign that the outbreak is tapering off. But the authors also warned that China should prepare for a "possible rebound of the epidemic."

Severe cases among healthcare workers have gone down considerably

The new study offers one of the broadest pictures of how the virus operates in humans so far. The results showed that the majority of patients have been men between the ages of 30 and 69 in Hubei Province.

More than 80% of cases in China have been mild, the research found - those patients might experience a fever or dry cough, but they aren't likely to have difficulty breathing or develop a severe lung infection within 24 to 48 hours. More severe cases of COVID-19 are marked by pneumonia-like symptoms.

Less than 5% of the cases in the study were critical; those patients had respiratory failure, septic shock, or multiple organ failure. Only half of the critical patients died.

Healthcare workers represented around 7% of the confirmed cases.

The number of critical cases among healthcare workers in China also declined from early January to early February, the study found. At the start of the outbreak, around 45% of cases among healthcare workers were severe or critical and around 5% were deadly. By early February, less than 9% of the cases were severe or critical and only 0.3% were deadly.

Another spike in cases could come in the coming months

The COVID-19 outbreak began as hundreds of millions of people prepared to travel for the Chinese Lunar New Year - one of the largest annual human migrations in the world. Many Chinese cities called off their festivities because of the virus, and more than 50 million people in China's Hubei province have been under lockdown since late January.

All transportation in and out of Wuhan has been halted.

Despite these extreme efforts, the coronavirus spread from Wuhan to the rest of mainland China within 30 days, according to the study. But the authors said the outcome could have been worse if China had not shut down entire cities, canceled New Year celebrations, rapidly built new hospitals, and required people in Wuhan to wear masks.

"The massive vigorous actions taken by the Chinese government have slowed down the epidemic in China and curbed spread to the rest of the world," they wrote.

Thus far, around 900 cases have been reported outside the Chinese mainland - around 1.3% of the global total.

But the Chinese CDC expressed concern about what could happen after the quarantines end. The authors warned that a spike in cases could be imminent once Chinese residents return to school and work.

"Although the epidemic appears to be in decline in the lead up to February 11, 2020, we may yet face more challenges," the researchers wrote. "We need to prepare for a possible rebound of the COVID-19 epidemic in the coming weeks and months."

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