An 11-month old girl has died after contracting the coronavirus, becoming Hong Kong’s youngest pandemic-related victim and the third such death of young ­children in the past fortnight.

Health authorities said the baby, who had “good past health”, was in a stable condition until 4am on Saturday, when she developed a fever and started to suffer from convulsions. She was brought to the accident and emergency department of Tseung Kwan O Hospital, intubated and then transferred to the intensive care unit at Queen Elizabeth Hospital in Yau Ma Tei.

She was given the antiviral drug Remdesivir, but her condition worsened rapidly and she suffered cardiac arrest at noon on Saturday. The baby died on Sunday night.

“The case was referred to the coroner for further investigation, as the patient was just admitted for one to two days,” said Dr Lau Ka-hin, a chief manager at the Hospital Authority. “We cannot identify the cause of death at this moment. We will discuss with the parents as well as pathologists how to carry out the coroner examination.”

He added that the baby’s twin sister, eight-year-old brother, parents and grandparents had also tested positive for the virus.

Professor Lau Yu-lung, a paediatrician and member of the government’s Advisory Panel on Covid-19 Vaccines and Scientific Committee on Vaccine Preventable Diseases, said young children had not been exposed to other types of common human coronavirus, which also caused flu-like symptoms, in the past, and therefore had not built up much immunity.

Lau noted that early stages of physical development also made children more prone to serious complications after contracting respiratory viruses.

“The only way to change destiny is to get vaccinated as soon as possible. Those aged three or above should do it quickly, it doesn’t matter which vaccine,” Lau said. “For those who are too young to get the jab, their caretakers need to get inoculated immediately if they haven’t already.”

In Hong Kong, children as young as three can receive the Chinese-made Sinovac jab, while those aged five to 11 are able to take the German-produced BioNTech vaccine.

Lau urged the Hospital Authority to centralise information on all child Covid-19 patients who were in a serious condition and hold a daily telemedicine conference to provide the best treatment for patients.

He also said health authorities should conduct genome sequencing on these patients as soon as possible to see whether the BA. 2 subvariant of Omicron which had already become dominant in Hong Kong had mutated.

Dr Patrick Ip Pak-keung, a clinical associate professor of paediatrics and adolescent medicine at the University of Hong Kong, said children who were admitted to hospital with Covid-19 during the fifth wave were often found to suffer convulsions, which could cause their condition to worsen.

“If the virus affects the brain, it can cause encephalitis,” he said, adding that the virus could also cause frequent convulsions, depriving the brain of oxygen.

Ip said it was rare to see a child or baby in a serious or critical condition before Hong Kong’s fifth wave of coronavirus infections.

“There may have been misconceptions before as some parents thought that the Omicron variant could not be very lethal to children, or even said it was just the flu. But this time the alarm was sounded,” Ip said.

Last Tuesday, a three-year-old girl with no underlying medical issues died at Hong Kong Children’s Hospital after being transferred in critical condition from Prince of Wales Hospital. Sources said the fatality was caused by acute brain inflammation triggered by her Covid-19 infection.

On February 11, a four-year-old boy who was sent to Pok Oi Hospital after vomiting and collapsing at his home in Yuen Long was certified dead. He tested preliminary-positive for the virus.

Lau advised parents and caretakers to monitor children for signs including difficulty in breathing, sounds of grunting, persistent high fever, vomiting or coldness to the extremities.

Parents should also call an ambulance if an alert, active and playful child becomes unusually quiet and inactive, loses their appetite and urinates less frequently, he warned.

Data from the Centres for Disease Control and Prevention in the United States showed 970 Covid-related deaths involving minors took place between January 2020 and February 2022. Of those, 307 were up to four years old, making up 31.6 per cent of child Covid-19 deaths, or 0.03 per cent of all deaths tied to the virus in the US.

In Qatar, a three-week-old baby with no known medical or hereditary conditions died last month as a result of severe Covid-19 infection, according to a statement from the country’s Ministry of Public Health.