The centre said the resurgence could be attributed to a few factors, such as people not getting vaccinated, not receiving the latest vaccination and waning natural immunity.
Twenty-four cases of whooping cough were registered in Hong Kong in the first quarter of the year and four more since then, bringing the total to 28 as of Thursday. Of these, 22 were locally acquired infections, while the rest were imported from mainland China or overseas.
Figures from the centre also showed that 19 cases – or nearly 70 per cent – affected infants and children aged up to 17 years. The remaining nine were adults, including five with unknown vaccination history and one who was unvaccinated.
Whooping cough is an illness with initial symptoms such as runny nose, sneezing and a low-grade fever. As the cough gets more severe, bacteria can infect the lungs and, in severe cases, lead to seizures and coma.
The latest caseload in Hong Kong is a significant increase from 2023, when just 15 whooping cough infections were recorded for the entire year. In 2020, the year the Covid-19 pandemic broke out, there were 22 cases. Those numbers plummeted to two and three respectively in the following two years.
In pre-Covid years, the city recorded 110 cases in 2018 and 96 in 2019.
The resurgence of whooping cough cases in Hong Kong this year has been mirrored elsewhere around the world.
England saw a steady increase in infections over the first quarter of the year, rising from 556 in January to 918 in February and 1,319 in March. These cases included five infants who died after contracting the illness.
There was also a significant increase on the mainland, which recorded 59,458 cases and 13 deaths over the same period.
In the Philippines, more than 2,500 infections, including 96 deaths, were logged this year as of May 11, compared with 20 cases in 2021 and four in 2022.
Dr Mike Kwan Yat-wah, an honorary clinical associate professor from the University of Hong Kong’s department of paediatrics and adolescent medicine, warned that whooping cough could cause brain damage or even death in severe cases.
He urged parents to be on the lookout for warning signs in their children.
“It is dangerous when your child’s skin or lips turn purple or blue when they are coughing,” he said.
Whooping cough can be prevented through vaccination, which the government offers to babies from two-months-old and Primary One students through its immunisation programme.
Pregnant women are also advised to receive a dose of the vaccine between 26 and 34 weeks of gestation to pass on protection to their infants.
Health authorities urged pregnant women, as well as infants aged under six months who have not received the first three doses of vaccines, to refrain from travelling to places with whooping cough outbreaks.
