28th May 2022 – (Hong Kong) Cases of Omicron sub-lineage BA.2.12.1 variant have been found successively in Hong Kong recently.
David Hui, a government expert consultant and chair professor of the Department of Respiratory System of CUHK, said that many cases found did not have an epidemiological relationship, and it is expected that variant virus BA. 2.12.1 has entered the community and an invisible chain of transmission has been created. Compared with the current circulating virus strain in the community, the vaccine antibody is weaker against it and the transmission is 25% higher, but there is no evidence that it will cause more severe illness. Hence, vaccination can still reduce death and severe illness, and it is expected that the number of confirmed cases in Hong Kong will remain in the low three digits.
In response to the increase in outbound travel due to relaxed border reopening measures implemented by Japan and South Korea, Hui said that if the supply of hotel rooms in Hong Kong is sufficient, the flight suspension mechanism can be cancelled. However, the World Health Organisation recommends 10 days of quarantine after entry and another 3 days for asymptomatic infections. Therefore, it is difficult for the government to reduce the quarantine period from the current 7 days to 5 days. He said that most of the cases could be detected during hotel quarantine within 7 days, but the incubation period of some cases varies. In the past four waves of the epidemic, there were many positive tests which were only recorded after 7 – 10 days. Therefore, it is still recommended to maintain the quarantine measure in hotels during the first week of entry before implementing the home quarantine during the second week.
As for whether a fourth dose is needed, he said that the T-cell response of 18-59-year-olds who received three doses is already very good. The fourth dose only raises antibodies for about two months, and the protection benefit is short-lived, so it is only recommended for high-risk groups such as front-line medical staff, cross-border drivers and overseas students, etc.
Even if the fourth dose is not administered, T cell protection can still reduce the severity and death. The fourth vaccine is optional for people aged 18 to 59, not mandatory. For citizens over 60 years old and those with immune disorders, due to their poor immune response, the fourth dose is recommended.