Taipei, May 4 (CNA) A pilot and a flight attendant at China Airlines (CAL), one of Taiwan's largest carriers, tested positive for COVID-19 on Tuesday, bringing to 28 the number of cases linked to the carrier and an airport hotel in Taoyuan, according to the Central Epidemic Command Center (CECC).

The pilot, a Taiwanese male in his 30s, flew to the United States on April 16 and returned on April 18.

He tested negative for COVID-19 twice in Taiwan, the first time on April 21 after completing the three-day quarantine required of domestic flight crew members. A further test conducted on April 25 as part of a mass testing program of CAL pilots also came back negative.

On May 1, the pilot developed a fever, cough and runny nose and the third test came back positive, according to the CECC.

The CAL flight attendant is a Taiwanese woman in her 20s who flew to the U.S. April 22-25. After returning to Taiwan, she stayed at the Novotel Taipei Taoyuan International Airport hotel for the required three-day quarantine.

She tested negative for COVID-19 before checking out of the hotel on April 28.

However, after a Novotel manager was confirmed with the disease on April 29, the flight attendant was taken to a government quarantine center that evening. A COVID-19 test she took the next day came back negative.

A few days later, she developed a headache, stomach pains and hot flashes, subsequently testing positive for COVID-19 on Tuesday.

As the pilot and flight attendant visited a bar together in Taipei, the CECC is looking into whether one of them infected the other.

As of Tuesday, 11 CAL pilots, eight relatives of CAL pilots, a CAL flight attendant, five people who worked at Novotel and three of their family members have tested positive for COVID-19 over the past two weeks, according to the CECC.

The cases of the Novotel employees, their family members, and the pilots' relatives have been classified as domestic cases, but the CECC has not yet classified the infections of flight crew members as domestic or imported.

Because some flight crew at CAL stayed at the Novotel before testing positive, and the genome sequencing of the virus in the pilots and a hotel employee matched, it is likely the cases are connected, though the chain of infection is unclear, the CECC said.

The Novotel airport hotel is part of CAL's complex in Taoyuan, which comprises the Taiwanese carrier's headquarters and training facilities.

The hotel is also used to quarantine flight crews from CAL and other airlines, as well as providing accommodation, conference hosting and dining services to the general public.

In addition to the cases linked to CAL and the airport hotel, Taiwan also reported six imported cases on Tuesday from Indonesia, Thailand, India and the Philippines.

Three of the cases involve foreign nationals coming to work in Taiwan, one is an international student and the remaining two are Taiwanese nationals returning from working overseas.

To date, Taiwan has recorded 1,153 cases of COVID-19, 1,009 of which have been classified as imported. Of the total, 1,067 have recovered, 12 have died, and 74 are in the hospital, according to CECC statistics as of Tuesday.

Globally, COVID-19 has infected over 153 million people in 193 countries and regions, with more than 3.2 million fatalities, CECC figures show.