Health experts have disputed claims by Hong Kong's leader that Covid-19 is six times more fatal than the flu, saying the mortality rates for the two respiratory illnesses were similar, partly because of high levels of immunity.
The medical specialists on Wednesday (Sept 14) estimated the fatality rate for the coronavirus in Hong Kong stood at 0.098 per cent, close to the 0.1 per cent recorded for influenza, citing the city's high Covid-19 vaccination coverage and natural immunity levels.
The Covid-19 fatality rate of 0.6 per cent put forward by city leader John Lee Ka Chiu on Tuesday "failed to differentiate between this current wave and the fifth wave during February and March", said Dr Leung Pak Yin, a former chief executive of the Hospital Authority.
"With the build-up of the immunity barrier in the community, the [Covid-19] death rate in Hong Kong since May has been similar to that of flu," Leung said on social media.
Citing government data, Lee had warned against equating Covid-19 with influenza and described the city's epidemic situation as still "critical".
"People should not just think that Covid is a normal flu, because if you look at our figures we have lost 9,000 lives just because of Omicron when every year we lost about 300 lives because of flu," he said.
But Leung explained that Lee had calculated the mortality rate by dividing the overall number of Covid-related deaths as of September 4, which was 9,511, by the total number of cases over the same period, which stood at 1,569,768.
The former authority chief said a more accurate number would be to divide the 356 deaths since May 15 by the 363,469 cases from the same period, which would put the mortality rate at 0.098 per cent.
The latest surge in infections had started in mid-May, as officials relaxed several social-distancing curbs and cases declined to their lowest point since the city's fifth wave began, he said.
Leung added that another variable to consider was that the surge was largely driven by the Omicron subvariant BA.5, instead of the BA.2 strain, which was increasingly reported during February and March.
"Analysing data has to be precise. Death rates vary according to the mutation of the virus, and the community infection situation," he said.
Professor David Hui Shu Cheong, a government pandemic adviser, echoed Leung's points, saying the recent coronavirus fatality rate remained low due to the prevalence of hybrid immunity among the population, referring to a level of natural resistance achieved through a combination of inoculation and past infections.
According to the latest government figures, around three-quarters of all eligible vaccine recipients in Hong Kong had taken the recommended three doses, while more than 90 per cent had received two shots.
Dr Joseph Tsang Kay Yan, chairman of the Medical Association's advisory committee on communicable diseases, said the recent death rate could be lower than 0.098 per cent because of under-reporting of infections.
"There are people who tested positive via self-administered rapid antigen tests and don't report to the government for fear of being quarantined.
"This could result in a larger denominator in the equation and hence a smaller death rate," he said.
"Moreover, the official figures included people who only died with Covid-19 but the direct cause of death was not the disease."
Tsang argued that it was pointless to include deaths from the various stages of Hong Kong's epidemic, since they involved different strains of the Covid-19, such as the more deadly Delta variant.
BA.5, one of the most prevalent viral strains during the recent surge, was characterised by a higher transmission rate and a lower likelihood of producing severe cases, he said, which resulted in a smaller number of fatalities.
The number of related deaths per day in Hong Kong has remained below 20 for the past two weeks, while critical cases have hovered between 45 and 65, even when the daily infection tally previously passed the 10,000 mark.
Appearing at a press briefing on Wednesday, Dr Chuang Shuk Kwan, of the Centre for Health Protection, agreed the current fatality rate was around 0.1 per cent.
"In the fifth wave after May, the overall death rate is certainly lower than that from December to April. I think that is because many people had been infected before, and more people had got vaccinated," she said.
But Chuang added that the mortality rate among elderly Covid-19 patients could be higher, but not to the extent suggested by Lee.
"If you look at some 400 deaths since May 1, about 70 per cent are aged above 80, accounting for about 320 people and a gross death rate of about 0.2 per cent," she said.
Respiratory medicine specialist Dr Leung Chi Chiu also said the figures for the flu and Covid-19 in Hong Kong were similar, but explained it was the result of "active intervention, and not the intrinsic attribute of virus or by lying flat".
Such interventions included government efforts to boost vaccinations, earlier case detection and the increasing use of antiviral medicines to treat patients, he said.
This article was first published in South China Morning Post.