The number of coronavirus cases outside China could see a tenfold increase every 19 days in the absence of "strong intervention" by government officials worldwide, a study has found.

Chinese researchers believe that "34 unobserved founder patients" with "mild symptoms" triggered the spread of COVID-19 outside mainland China.

"The situation is dangerous" and "powerful actions on public health should be taken to combat this epidemic all over the world," according to the study.

Other experts like Harvard epidemiologist Marc Lipsitch have also issued warnings, stressing that COVID-19 could reach pandemic levels and infect around 3 billion people globally.

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The number of coronavirus patients outside mainland China could climb tenfold every 19 days, if countries don't enforce stringent restrictions to deal with the mounting crisis, researchers have found.

A study, led by geneticist Jin Li, of Shanghai's Fudan University, found that an estimated "34 unobserved founder patients" triggered the spread of COVID-19 outside mainland China.

They may have only presented with "mild symptoms," the study says, and so didn't go to a hospital to get tested for coronavirus.

Based on data gathered through the end of February, the researchers built a "mathematical model to capture the global trend of epidemics outside China."

"The situation is dangerous," the study said, underscoring the need for "strong intervention."

"Powerful actions on public health should be taken to combat this epidemic all over the world," the researchers wrote, highlighting China and Singapore as two countries where drastic containment measures have helped to control the spread of the coronavirus.

These findings were published on medrxiv.org, which is a preprint server for health sciences, according to its website. This means the study has not yet been peer-reviewed.

According to the South China Morning Post, a woman who traveled from Wuhan, in Hubei province, to Thailand was the first coronavirus carrier outside China. She tested positive for COVID-19 on January 13.

As of Saturday, the illness has now hit every continent, except Antarctica, and affected over 101,000 people.

Other experts have also issued equally bleak predictions, with Harvard epidemiologist Marc Lipsitch telling the Deep Background podcast that the coronavirus has the potential to erupt into a pandemic that would affect around 3 billion people or between 40% and 70% of the world's adult population.

A webinar presentation hosted by the American Hospital Association projected that there could be as many as 96 million cases in the United States alone along with 4.8 million hospitalizations and 480,000 deaths associated with the novel coronavirus.