Explainer | When Omicron and Delta collide: all you need to know about Hong Kong’s fifth Covid-19 wave. And is there light at end of tunnel?
- Four clusters threaten to overwhelm city’s pandemic strategy, with residents returning to living under strict social-distancing measures
- Current fifth wave has raised new concerns, such as animal-to-human transmission and the actual effectiveness of masks
Hong Kong’s Covid-19 situation took a worrying turn after Christmas celebrations last month, when the Omicron variant slipped into the community and sparked the city’s fifth wave of infections.
Weeks later, the Delta coronavirus variant also surfaced locally, with infections thought to be spread by hamsters imported from the Netherlands.
The Post explores how Hong Kong is currently weathering the pandemic.
1. What are the major clusters?
Moon Palace cluster: A quarantine-exempt aircrew member returning from the United States flouted home isolation rules by dining with a family member in a restaurant called Moon Palace and visiting a friend in Tuen Mun in late December. A total of 16 Omicron cases involving diners at the Kowloon Tong eatery and residents in Tuen Mun were later detected.
Dance cluster: A group that has grown to 53 confirmed cases originated from a 28-year-old flight attendant returning from the US. She carried the Omicron variant and infected her socially active mother, who danced in Victoria Park and visited a few restaurants.
Silka Seaview Hotel cluster: The biggest cluster so far. A resident returning from Pakistan was thought to be infected by another guest at the quarantine hotel in Yau Ma Tei. Her infection was only detected days after she completed her 21-day hotel stay. The Omicron variant eventually spread to her family members and close contacts, affecting people in schools, various locations in Sham Shui Po, and a Kwai Chung public housing estate, where close to 280 cases have been uncovered as of Tuesday. The escalating situation at the estate forced a lockdown of three blocks, and testing orders for others.
Pet shop cluster: Officials also uncovered possible animal-to-human transmission involving the Delta variant among a batch of hamsters imported from the Netherlands in mid-January. The cluster has now grown to 16 infections, including staff and customers at the chain’s various sister shops, as well as their close contacts.
2. What’s there to note about the fifth wave?
Kwai Chung Estate, at the centre of a superspreading event, is a large housing complex. Thousands of residents living in three out of the 16 buildings have been locked down for five to seven days, while infections have been found in nine other blocks. The number of cases has surged exponentially from nine to more than 270 in merely six days.
The city is also battling two variants at the same time – Delta and Omicron. The incubation period for Delta is longer, complicating pandemic control strategies. The much more transmissible Omicron variant also sparked concerns over the effectiveness of masking. Experts have found short-range airborne transmission on several occasions, including cross-infection in a hotel and within an examination setting in a school, where students and teachers had put on masks properly.
3. How can we be sure of animal-to-human transmission in Hong Kong?
The latest genome analyses found significant similarities between samples taken from hamsters and the shopkeeper, suggesting such transmission pathways.
Yet, the woman’s virus sample had a difference of four genetic mutations from the strain found in two other patients – a customer and her husband. Officials said this showed the shopkeeper might not have directly transmitted the virus to the customer, who could have been exposed to the animals in the pet shop or caught the infection from her hamster at home.
Authorities also found positive samples in the shop’s warehouse in Tai Po, but the shopkeeper had never visited the premises.
An expert leading the genome analysis of Covid-19 cases added that hamster-to-human transmission of the virus was theoretically possible, as a similar spread had occurred between people and mink in Denmark.
4. Is Hong Kong back to tough social-distancing measures?
Vaccine bubble arrangements banning entry to government venues for those who are not inoculated will also be extended to cover more places, such as restaurants and schools.
5. So is masking effective at all?
Health experts believe masks still offer a measure of protection, but recommend an added layer of shielding with cloth masks, face plates or even glasses.
Vaccination is still considered the best way to avoid serious complications from infection.
6. Should Hong Kong opt for ‘living with the virus’?
Hong Kong has prioritised the reopening of the border with mainland China, and therefore aligns itself with Beijing’s “dynamic zero-infection” approach, meaning an outbreak should be contained as early as possible.
Leading government health advisers have said the city can only live with the virus when vaccination rates across all age groups hit a high mark, such as 90 per cent. Other epidemiologists have argued that the current approach is not sustainable, though they agree the low inoculation rate for the elderly is worrying.