Elderly patients who have gotten one or two vaccine jabs but been infected also need to go in for an extra dose three months after they have recovered. However, those who have already received three jabs before getting infected can rest easy as they don't need any more doses.

The proposals came after experts from two scientific committees under the Department of Health met on Wednesday to discuss the SAR's inoculation program.

"Local data showed that three doses of Covid-19 vaccines are highly effective in reducing hospitalizations and deaths across all age groups in the adult population," the experts said late Wednesday.

The recommendation backtracks slightly on the earlier government advice, which said that people who have received two jabs before being infected do not need to take a third one and those who were not vaccinated before an infection should receive only two jabs after recovery.

But experts said on Wednesday that elderly aged 60 or above and care home residents are a different category.

"As the majority of local fatal cases in the fifth wave of the Covid-19 epidemic have been persons aged 60 or above, [the experts] thus recommend persons aged 60 years or above receive an additional dose," with an exception to those who already had three jabs.

Additionally, elderly people who were unvaccinated before getting infected should receive the first dose one month after recovery, the experts said.

They should then get a second jab one to three months after the first, and a third jab another three months afterward.

The experts also said all recovered persons without a history of vaccination in the past can be vaccinated one month after recovery.

They also had no objection to recovered patients receiving their next Covid-19 vaccine dose for personal reasons - such as before going abroad to study or to fulfill a requirement for overseas travel - at a shorter interval of no less than 28 days after recovery.

The experts concurred that vaccinations should be offered to persons unsure if they had a previous infection, and they should proceed as if they had not been infected. This is as vaccines are safe for people with previous Covid infections, and prior screening before administration is not required.

As for new vaccines, including those specifically targeting the Omicron variant, experts said they are in different stages of development or have been put into use late last year.

As of now, there is limited scientific evidence on their use as booster shots, but they added that the scientific committees would keep in view the development of these vaccines.

University of Hong Kong health expert Ivan Hung Fan-ngai yesterday said that the elderly and immunocompromised people should receive a fourth jab because their antibody level drops quickly eight weeks after getting the third jab.

Hung also said that young and healthy persons who have been infected recently do not have to receive an additional jab shortly after recovery, because their natural immunity after an Omicron infection lasts for more than six months.

Those recovered patients could receive a new-generation vaccine targeting Covid-19 variants later this year, he added.