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Scientific Committees under CHP update interim recommendations related to COVID-19 vaccination and quarantine requirements for vaccinated inbound travellers and vaccinated close contacts
     The Scientific Committee on Vaccine Preventable Diseases and the Scientific Committee on Emerging and Zoonotic Diseases under the Centre for Health Protection (CHP) of the Department of Health (JSC) convened a meeting today (June 9), joined by the Chief Executive's expert advisory panel (EAP), to discuss interim recommendations related to the interchangeability of COVID-19 vaccines, eligible age groups for receiving the Comirnaty COVID-19 vaccine, the use of COVID-19 vaccines for elderly, and quarantine requirement for vaccinated inbound travellers and vaccinated close contacts.  
     During the meeting, the JSC-EAP discussed the use of different types of COVID-19 vaccines for the first and second dose. It was noted that current evidence on the interchangeability of COVID-19 vaccines are limited and further studies on the interchangeability of COVID-19 vaccines involving different vaccine types are underway. There are no safety concerns reported so far for mixing viral vector vaccine with mRNA vaccine. Preliminary evidence showed that mixing viral vector vaccine with mRNA vaccine may be more reactogenic than without mixing schedule. The reactogenicity symptoms reported were short-lived. Members of the public are advised to complete both doses of the series with the same product when possible. In exceptional situations where the vaccine recipient is unable to complete the series with the same type of vaccine (e.g. due to anaphylaxis after the first dose; or if the vaccine is no longer available or accessible), vaccination with another COVID-19 vaccine may be considered on a case-by-case basis.
     Noting the Government's recent approval of lowering of the age limit for receiving the Comirnaty vaccine to age 12, the JSC-EAP agreed that the Comirnaty vaccine has a high efficacy against symptomatic COVID-19 disease. Vaccination will be important to protect adolescents against symptomatic COVID-19 disease and to reduce community transmission, as well as to increase the overall community immunity. The JSC-EAP also noted that there were overseas reports of mild myocarditis/pericarditis following vaccination with Comirnaty COVID-19 vaccine, and the probability on a possible link between the second dose and the onset of myocarditis among young adults. There is a need to continue monitoring ongoing studies on this possible link. Considering the benefits of Comirnaty COVID-19 vaccine in reducing deaths and hospitalisations due to COVID-19 infections outweigh the risks, the JSC-EAP recommended the use of Comirnaty COVID-19 vaccine for adolescents aged 12 - 15.
     In addition, the JSC-EAP highly recommended COVID-19 vaccines for the elderly as they are the group with highest risk of complication and death from COVID-19 disease. Inactivated vaccines, e.g. influenza vaccines, which have been used in elderly for a long time, successfully prevent influenza complications and outbreaks in residential care homes for the elderly. Any elderlies who have received influenza vaccines before can safely receive COVID-19 vaccines. For the frailest elderlies, the benefit versus risk may have to be carefully weighed. 
     During the meeting, the JSC-EAP has reviewed the criteria concerning the quarantine arrangement for fully vaccinated inbound travellers and made recommendations based on the prevailing scientific evidence on COVID-19 and COVID-19 vaccines. The duration of compulsory quarantine for inbound travellers could be shortened to 7 days of quarantine at a designated place plus 7 days of self-monitoring with multiple polymerase chain reaction (PCR) testing, provided that the following three criteria have been satisfied:
(a) Documented proof of completion of the full course of recognised COVID-19 vaccines, and 14 days have passed from the date of completing the full course of vaccination; and
(b) Result of PCR of the respiratory specimen taken on arrival is negative; and
(c)  Positive IgG/total antibody against SARS-CoV-2 spike protein/ surrogate neutralising antibody, conducted in Hong Kong after arrival.
     The purpose of checking antibody is to show evidence of response to vaccination. If the serology test is negative, the shortening of quarantine period could not be considered. The serology test should be done in Hong Kong on arrival and is valid for the coming three months. For travellers who have recovered from previous COVID-19 infection, they would be required to receive one dose of COVID-19 vaccine in order to be considered as fully vaccinated. The public is not encouraged to check their antibody level after vaccination. A negative result or low antibody level may not correlate with lack of protection.
     The JSC-EAP also discussed the list of recognised COVID-19 vaccines that would be accepted for consideration of adjusting the quarantine requirement for inbound travellers. Apart from the COVID-19 vaccines already recognised for use in Hong Kong, vaccines on the World Health Organization (WHO) Emergency Use Listing or Pre-qualification lists, vaccines recognised for use by Stringent Regulatory Authorities as designated by WHO or the National Medical Products Administration, as well as vaccines recommended by the JSC-EAP (Sputnik V) would also be accepted.
     The same list of recognised COVID-19 vaccines would also be accepted for the consideration of shortening of quarantine period for vaccinated close contacts.

     Details of the interim recommendation will be available at the CHP’s website www.chp.gov.hk/en/static/24008.html.
Ends/Wednesday, June 9, 2021
Issued at HKT 23:59
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