The boy developed a fever and sore throat on May 12. He was taken to a private doctor in Tsing Yi the following day and a Covid test was ordered.
On May 15, health authorities reported the boy was infected and they didn’t know how he had caught the virus.
More than 20 students and teachers at the boy’s kindergarten in Ho Man Tin were sent to a hotel to undergo quarantine for 14 days.
But repeated negative tests since then suggest the boy is not carrying the virus, and nor does he have antibodies for it.
Henry Yeung, the private doctor who treated the boy, told RTHK that a saliva sample was submitted to a government outpatient clinic on May 13 and the test result came back as “indeterminate” the next day.
Yeung said he did not know why health authorities had classified the boy as a confirmed case on May 15, adding that they should clarify whether it was a false positive as soon as possible, given all the people sent into quarantine as a result of the suspected infection.
Earlier on Thursday, infectious disease expert Leung Chi-chiu said that if the boy was found not to be infected after all, Hong Kong would have gone 26 days with no untraceable infections.
Leung said when the territory hits 28 days, officials can consider holding talks with their mainland counterparts on resuming cross-border travel.
The Centre for Health Protection announced one new imported Covid-19 case on Thursday, involving a 26-year-old woman who flew in from Indonesia. There were no new domestic cases for the fourth day in a row.