A woman from Sichuan, China, has been diagnosed with Covid-19 after previously testing negative for it eight times.

Quarantined as suspect patient for three weeks

The 56-year-old hotel worker, surnamed Tang, had been in quarantine for three weeks, according to Sichuan Online.

She worked at a hotel in Chongqing as a dishwasher, and returned to her hometown in Anyue on Jan. 23 to celebrate Chinese New Year with her family.

However, one of her colleagues at the hotel was confirmed to have contracted the virus, and Tang was placed under quarantine on Feb. 2.

From Feb. 7 to Feb. 23, medical workers conducted eight tests on Tang by taking throat swabs.

The workers then carried out nucleic acid detection tests using PCR (polymerase chain reaction) techniques to check if she had contracted the virus.

All eight tests then came back negative.

Tang was later transferred from a hospital in the county to another hospital in Ziyang city on Feb. 21.

Doctors finally confirmed that she was infected with Covid-19 on Feb. 24 after conducting further clinical and laboratory tests.

This means that a total of nearly three weeks had passed since Tang was quarantined.

Incubation period could be more than 2 weeks

Although Covid-19 is typically presumed to have an incubation period of 14 days, the Chinese government has revealed that it could potentially be much longer.

Reuters reported that a 70-year-old man in Hubei was infected with the coronavirus, but only showed symptoms 27 days later.

This longer incubation period could pose problems for authorities trying to clamp down on the spread of the virus.

Another study also revealed the incubation period can go up to 24 days although that data point was later clarified as an anomaly.

One factor that distinctly differentiates Covid-19 from SARS and MERS, is the absence of certain symptoms like fever in suspect cases at initial phases.

Which means that temperature screenings could potentially miss out on infected people who are asymptomatic.

Top photo from Getty Images.