BEIJING, Feb. 21 (Xinhua) -- Convalescent plasma therapy has proved to be effective on severe cases of novel coronavirus disease (COVID-19), a Chinese official said on Friday.

More than 100 patients who have recovered from COVID-19 have donated plasma, and the plasma can be prepared into therapeutic products to treat more than 200 patients with severe and critical symptoms, said Xu Nanping, vice minister of science and technology, at a press conference in Beijing.

The therapy so far proves effective on patients, said he.

According to the official, among the first 11 patients who received the therapy in Wuhan, six have viremia which means they had the presence of the virus in their bloodstream.

Two to three days following the therapy, viremia disappeared and the patients' conditions were improved.

In northern China's Shanxi Province, patients who were once in critical condition turned stable after receiving the convalescent therapy.

He added that it will be further applied to patients with severe and critical symptoms, as well as patients with rapid onset of COVID-19.

A total of 20 teams have been sent to 11 provinces to collect convalescent plasma. Local health authorities have been asked to provide support for plasma collection.

He called on recovered patients to donate plasma.

Along with convalescent plasma therapy, traditional Chinese medicine and Chloroquine Phosphate, an antimalarial drug, have been included in the treatment guidelines, Xu said.