Taipei, Feb. 21 (CNA) Taiwanese medical authorities are increasingly perplexed by the country's 24th novel coronavirus (COVID-19) case -- a woman in her 60s from northern Taiwan, with no recent history of travel abroad and an unknown source of infection.
The woman's case, which was announced Wednesday by the Central Epidemic Command Center (CECC), may stretch back to the early days of an outbreak that has since spread across the globe, sickening over 75,000 people and killing more than 2,200.
According to a timeline provided by the CECC, on Jan. 6 the woman came in contact with her daughter's classmate, who had recently returned from Hangzhou, China.
Doctors who treated the woman, however, believe this encounter was too early to have been the source of infection.
On Jan. 22, the woman fell ill, and after visiting two clinics over the course of a week, she was admitted to a hospital on Jan. 30.
On Feb. 10, she was transferred to the hospital's intensive care unit with respiratory failure, and on Feb. 17 was moved into a negative-pressure isolation room, before testing positive for the virus on Feb. 19.
On Feb. 21, her granddaughter, who had visited her in the hospital on Feb. 12, was diagnosed as Taiwan's 25th case of the virus, and the woman's daughter was confirmed as the 26th case.
In interviews with CNA, virology experts following the woman's case offered their opinions on the possible source of infection, as well as the case's implications for Taiwan's outbreak prevention efforts.
According to a health care worker involved in the government's coronavirus testing efforts, researchers are using an international virus genome database to track the virus' mutations based on time and location.
The bewildering thing about the 24th case, the source said, is that the virus the patient was infected with resembles the virus structure from the beginning of the outbreak, as opposed to that seen in more recently affected locales, such as Japan or South Korea.
From a virological standpoint, this suggests that the virus was present in her body for an extended period of time, the source said.
Meanwhile, Hwang Kao-pin (黃高彬), director of the Pediatric Infectious Diseases Division at Taipei's China Medical University Hospital, said the many trips to see a doctor made by the woman before her diagnosis, and the potentially large number of people she came in contact with, made finding the source of infection "a real nightmare."
Hwang also said the granddaughter might have contracted the virus while visiting her grandmother on Feb. 12, given the closeness of contact, although their meeting only lasted several minutes.
More broadly speaking, Shih Shin-ru (施信如), director of Chang Gung University's Research Center for Emerging Viral Infections, said the case shows Taiwan has reached a point where travel history can't be the only standard for judging risk of infection.
Recognizing this, the CECC has not only expanded its screening standards, but also gone back and administered tests on unexplained respiratory infections -- which is how they found the 24th case, she said.