Coronavirus: BioNTech third dose ‘not needed’ but final decision on extra shots for both Hong Kong vaccines postponed
- Full assessment of suitability of third shots for Sinovac jab not possible given lack of data, Hong Kong’s low inoculation rate
- Government committee advising on vaccine use delays to October its decisions on whether to recommend additional doses
Professor Lau Yu-lung, chairman of the Hong Kong government’s committee on vaccine preventable diseases, on Thursday said a lack of data and the city’s low inoculation rate, especially among the elderly, prevented a proper assessment of the pros and cons of administering third shots of the Sinovac jab.
He said the body, which was established under the Department of Health to provide science-based advice on vaccine use, would consider both types of jab in the round and had deferred the decisions to October.
Lau also stressed the two jabs were “similarly effective” from a personal protection perspective, and urged residents not to be alarmed by recent reports showing BioNTech’s version created 10 times more antibodies than Sinovac’s.
Officials also on Thursday imposed orders for an overnight lockdown and mandatory testing covering Block 6 of Handsome Court in Tuen Mun.
A person living in the area within the past three weeks had tested preliminary-positive after arriving from Dubai and was found to carry a mutant strain of the coronavirus.
Meeting the press on Thursday night along with the joint scientific committees’ chairmen, Dr Ronald Lam Man-kin, the Centre for Health Protection’s controller, warned Hong Kong was facing Covid-19 threats “both domestic and foreign”, given the meagre 4.8 per cent vaccination rate among over 80-year-olds, and the Delta variant gaining dominance around the world.
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Asked if increased uptake among the wider Hong Kong population would be enough to return city life to normality, Lam said social-distancing measures would depend on the state of the crisis, but added: “They would for certain be tighter than otherwise if the elderly remained largely unvaccinated.”
Lau, the committee chairman, however, said experts would need more time – two to three months – to reach a long-awaited decision on whether Hongkongers would need a booster jab.
“Many citizens have not had their first or second meal yet, how can we decide to give others their third meal,” he said using a food analogy, adding the World Health Organization would question the city’s allocation of vaccines especially in the context of shortages among the poor globally.
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The third reason Lau cited for the delay was a lack of large-scale trial data on the pros and cons of booster doses, which he hoped would be available by the autumn.
Lau however said the current consensus in the medical community was that BioNTech recipients would not need a third dose, with the possible exception of patients who had undergone organ transplants and would have difficulty producing antibodies from the vaccines.
The infectious disease expert said it was normal for inactivated vaccines such as the Sinovac one to require booster doses, pointing to the multiple polio jabs given to Hong Kong infants and schoolchildren.
However, Lau cautioned Hongkongers not to draw the conclusion that Sinovac jabs were less effective. He said differences in antibody levels only affected a person’s ability to stop spreading or catching Covid-19, but crucially, both vaccines generated similar T-cell immune responses, meaning they were “similarly effective” in preventing hospitalisation and deaths.
He urged those, especially the elderly who were worried of strong side effects from BioNTech jabs, to consider taking Sinovac.
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Lau added that only a more balanced uptake at a ratio of 6:4 in the Germany-produced jab’s favour could fully utilise the city’s limited stock and achieve 80 per cent inoculation coverage.
That ratio had shifted to 4:1 in recent weeks following the release of data on the differences in antibody levels between the two vaccines.
Exceptions could arise in emergent health situations, such as the need of having a rabies vaccine after being bitten by a dog.
Earlier on Thursday, two non-government health experts called for the city’s criteria for suspending passenger flights to the city to be tightened in the face of a rise in imported cases involving Covid-19 variants.
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Under the existing flight-ban mechanism, if a total of five or more passengers among all flights from the same place – regardless of the airline – test positive for the N501Y mutant strain, or other variant strains, within seven days of arriving, all passenger flights from there are banned for two weeks.
The ban would also be triggered if those variant strains were found among a total of 10 or more passengers from the same place during post-arrival testing at any time, including during quarantine.
“The previous changes to the flight-ban mechanism came on May 1 and it has not been adjusted since then,” Ho told a radio show. The rules were therefore set before the more infectious Delta variant was spreading on a global scale, he added.
Rather, Ho called for standards to be tightened so flight bans were triggered by three positive tests in the first instance, and five in the second.
Based on Ho’s analysis, the number of imported cases in Hong Kong involving variant strains was about 13 per cent in May, but had risen to 66 per cent in June. So far this month, about 85 per cent of the imported cases involved a variant strain, with most carrying the L452R or the Delta variant, according to his findings.
Respiratory medicine specialist Dr Leung Chi-chiu also backed tightening the rules, adding that designating a country as “extremely high risk” under the city’s classification of overseas threat levels for Covid-19 could also be deployed to prevent the spread of imported infections. Eight countries classified as such – including Britain, India, and the Philippines – are subject to indefinite flight bans.
