MANILA - The elderly are the most vulnerable to a new virus that has killed at least nine in China and sickened hundreds, the Department of Health said Wednesday.

Health Secretary Francisco Duque said those who died from the illness had underlying medical conditions such as cancer and diabetes.

"Mula sa mga naiulat sa atin, yung hirap ng paghinga o kakapusan sa paghinga ay posibleng sintomas na rin ito na tutuloy sa pneumonia o sa mabigat na komplikasyon o severe acute respiratory syndrome na pwedeng makamatay, lalong lalo na sa mga matatanda, yung mga may underlying medical problem," he told radio DZMM.

The Bureau of Quarantine remains on alert as the department awaits updates from the World Health Organization, Duque said.

"Dapat talaga pinagiingat na ang ating mga kababayan na tutungo ng China. Hintayin natin ang advisory ng WHO na oras-oras naman tayo ay nakikipag-ugnayan para sa pinakahuling ulat," he said.

The Philippines has started screening passengers arriving at the capital's main airport for fever and flu symptoms, after a 5-year-old from the central Chinese city of Wuhan arrived in Cebu City last Jan. 12 and tested positive for "non-specific pancoronavirus."

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Passengers who show fever and flu would be submitted to further quarantine checks, Health Undersecretary and Spokesperson Eric Domingo said in a separate DZMM interview.

Common symptoms of coronavirus infection include cough, fever, shortness of breath and breathing difficulty. In severe cases, it can cause pneumonia, acute respiratory syndrome, kidney failure and even death, Duque earlier said.

Vaccines and medicine against the novel (new) coronavirus have yet to be discovered, he added, but a strong immune system would prevent a person from contracting the illness.

"Wala akong maalala na merong nang nalikha na gamot o bakuna kundi puro supportive treatment lang, dahil kung malakas naman ang resistensiya eh kusang mawawala naman itong sakit, kung tawagin self-limiting," he said.