Flu outbreaks spike at Hong Kong schools with doctors warning winter will bring more serious cases
- More than 220 flu outbreaks have been recorded in primary and secondary schools since late August
- Doctor says people have not been exposed much to the flu virus in recent years so their immune systems have not been trained up
The number of flu outbreaks in Hong Kong’s primary and secondary schools has spiked since mid-September, with doctors warning of more serious cases to come in winter.
Centre for Health Protection data showed that the number of outbreaks in primary schools more than doubled from 23 in the week of September 10 to 53 last week.
A similar trend was observed among secondary schools, with the figure jumping from nine outbreaks to 28 over the same period, a threefold increase. And this week alone, 34 outbreaks had been reported in primaries and 22 in secondary schools up to Thursday.
Kindergartens also experienced an increase, from four outbreaks a week in mid-September to 11 this week.
However, the number of outbreaks recorded at care homes for the elderly and the disabled has remained under 10 each week.
Since Hong Kong entered the summer flu season in late August, more than 140 outbreaks have been recorded in primaries and about 80 in secondary schools as of Thursday.
Dr Mike Kwan Yat-wah, an honorary associate professor of the University of Hong Kong’s department of paediatrics and adolescent medicine, said the spike in influenza cases among children could be a result of the new school year starting in early September.
Another reason was the “immunity debt” phenomenon, he said, after social-distancing measures were put in place during the coronavirus pandemic.
“We have not been exposed much to the flu virus and our immune system has not been trained up … and so when the virus is around, we are more prone to infection,” Kwan said.
Respiratory medicine specialist Dr Leung Chi-chiu said the rise in reported outbreaks among primary and secondary schools could be a result of more frequent activities.
“Students can have lots of contact with each other during school activities, and the frequency of contact could be higher than for those in kindergartens,” Leung said, pointing to recess and extracurricular activities as examples.
He said care homes were less likely to be affected as the elderly had been exposed to the flu in past decades so they would have a certain level of immunity.
The vaccination rate among elderly residents in care homes was also higher than for schoolchildren, he noted.
According to the Department of Health, around 70 per cent of residents and staff at care homes for the elderly were vaccinated over the previous year, while the rate for children aged 12 or younger was roughly 50 per cent.
Leung warned that as the winter flu season was approaching, there was a chance more children would develop severe conditions because of the lack of exposure to the virus in the past few years and the overall low vaccination rate.
At least 12 children locally have suffered from serious flu conditions in the current summer flu season, including a five-year-old girl with good past health who died on September 21.
Chu Wai-lam, principal of Fung Kai No 1 Primary School in Sheung Shui, said he had noticed more students falling ill with the cold and flu recently compared with early September.
But the number of cases had not yet triggered any class suspensions, he said.
Chu said the school had arranged an on-site flu vaccination service for students in November. Students were also asked to take their body temperature at home and at school daily.
The city’s influenza vaccination subsidy scheme, targeting eligible groups such as children aged from six months to 17 years and people aged 50 or older, began on Thursday.
The government vaccination scheme, which hands out free flu shots to specific groups, as well as outreach services at schools and care homes, will start next Thursday.
