Reality check: Why 15K new cases of COVID-19 doesn’t mean the outbreak is exploding

On Wednesday evening, China announced its new numbers on cases of COVID-19, the novel coronavirus disease that has stricken the country.

It said it had 15,152 new cases and 254 new deaths — the biggest single-day increase yet.

But these numbers don’t mean the outbreak is spreading uncontrollably, experts say. Rather, it’s more a change to how cases are counted that has inflated the total.

“This increase that you’ve all seen in the last 24 hours is largely in part down to a change in how cases are being diagnosed and reported,” said Dr. Michael Ryan, executive director of the World Health Organization’s health emergencies program, at a press conference Thursday morning.

While 15,000 new cases is a big increase, Ryan said, not all these cases necessarily happened in a single day.

“Most of these cases relate to a period going back over days and weeks and are retrospectively reported as cases since, sometimes, back to the beginning of the outbreak,” he said.

2:41 Coronavirus outbreak: WHO says China ‘doesn’t need to ask’ for praise for its response to virus

Cases in Hubei province, which has seen the vast majority of COVID-19 cases so far, will now be counted on the basis of a clinical diagnosis, not only when they have been confirmed in a laboratory.

Get weekly health news

Receive the latest medical news and health information delivered to you every Sunday.

Sign up for weekly health newsletter Sign Up

By providing your email address, you have read and agree to Global News' Terms and Conditions and Privacy Policy.

That means that doctors could diagnose a patient with COVID-19 after seeing signs of lung infection on a CT scan, rather than sending a sample off to a lab to see whether the person has the virus. This is less accurate, as it could include other kinds of pneumonia, but it is much faster, experts say.

Other Chinese provinces, aside from Hubei, will still be reporting only lab-confirmed cases of COVID-19.

“The reason the Chinese health authorities decided to change the diagnostic procedure by including the clinical diagnosis, I assume, is because they lack diagnostic kits, delaying treatment of those with symptoms,” said Choi Jae-Wook, chairman of the scientific review committee of the Korea Medical Association.

0:33 Coronavirus outbreak: China Health Commission says death toll at more than 1,300

The change in the way cases are counted reflects a local policy in Hubei to promote early detection and isolation, said Qi Xiaolong, a medical professor at First Hospital of Lanzhou University in Gansu, China.

Waiting for a test to come back is slow, he said, and that could have consequences for public health.

“The case data would not be timely if Hubei uses nucleic-acid testing only to confirm cases, because patients there, without enough test kits and testing staff, need to wait for days to get out a result,” he said.

“Meanwhile, the quality of kit and sampling error will lead to a probability of false negative. The false-negative person might be the mobile source of infection in the community.”

2:05 Coronavirus outbreak: 2 patients at UCSD facility tested positive for virus, third person under investigation

Diagnosing the disease at the doctor’s office means patients can get treatment faster, Ryan said. Public health authorities can also get information on their travel history and who they have been in contact with faster and can act on that information to try to contain the outbreak.

“There have been some backlogs in testing, and this is also going to help in ensuring that people get adequate care and that adequate public health measures can be taken,” he said.

— With files from Reuters