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Coronavirus patients in northeastern China are reportedly taking longer to recover from the virus and to exhibit symptoms than patients from the original outbreak in Wuhan, one of China’s top doctors told state TV Tuesday.

Dr. Qiu Haibo, who is taking care of patients in the northeast, said the more than two-week incubation period is making it hard to keep the virus from spreading and could show the virus is changing, Bloomberg reported.

Patients in the northeast also mostly have lung damage rather than in their heart, kidney and stomach as in Wuhan.

CORONAVIRUS HAS MUTATED INTO AT LEAST 30 DIFFERENT STRAINS, STUDY STUDY FIND

At least 46 cases have popped up in three cities located just north of North Korea's border – Jilin City, Shulan and Shengyang – which are under lockdown again. Of those infected, 26 have been hospitalized, according to Bloomberg.

In this May 17, 2020, photo released by Xinhua News Agency, a medical worker collects sample for COVID-19 testing at the Tongji community in Shulan in northeastern China's Jilin Province. Authorities have tightened restrictions in parts of Jilin province in response to a local cluster. (Zhang Nan/Xinhua via AP)

In this May 17, 2020, photo released by Xinhua News Agency, a medical worker collects sample for COVID-19 testing at the Tongji community in Shulan in northeastern China's Jilin Province. Authorities have tightened restrictions in parts of Jilin province in response to a local cluster. (Zhang Nan/Xinhua via AP)

Last month, a study from Zhejiang University in Hangzhou, China, found the virus had mutated into at least 30 different genetic versions.

"Drug and vaccine development, while urgent, need to take the impact of these accumulating mutations, especially the founding mutations, into account to avoid potential pitfall," the study said.

The differences, however, could be because only the sickest patients were being treated when the virus first overwhelmed Wuhan and doctors can now pay more attention to the way symptoms manifest.

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“The longer period during which infected patients show no symptoms has created clusters of family infections,” Qui added, according to Bloomberg.