At a televised briefing on Sunday, the UAE government encouraged people to register for a third shot.
Until now, boosters were largely limited to people with health conditions, over 50s, and those who had the Sinopharm vaccine early on in the inoculation campaign.
“The Ministry of Health and Prevention … recommends all adults aged 18 and above who received the two primary doses of Pfizer-BioNTech more than six months ago take a booster shot,” said Dr Farida Al Hosani, government health spokeswoman.
The small number of residents who took the Russian-made Sputnik V were urged to take a booster. She did not state if those who took the Oxford-AstraZeneca vaccine were eligible yet.
“We advise everyone to make sure they received the booster shot on time and not to postpone — especially the elderly and those with chronic illnesses,” Dr Al Hosani added.
She said the body's immunity to coronavirus and its multiple strains would inevitably wane over time, prompting the need for booster doses.
The Omicron strain, which was first reported in South Africa, is potentially more contagious than previous variants, although scientists have said it is too early to tell how it will affect the effectiveness of Covid-19 vaccines.
Israel, which has vaccinated the majority of its population, shut its borders to all foreign travellers amid concern.
Last week, the UAE said 100 per cent of the population had received one dose of the vaccine, with 90.3 per cent having received two.
But Dr Al Hosani said there was still a need to push for full community protection.
“This percentage does not mean that every person in the population is vaccinated,” she said.
“There is a changing group of new residents, new visa holders, who will be followed up with and confirmed they have had two doses of the vaccine.”
Countries around the world have rushed to close their borders to African nations after the World Health Organisation declared Omicron a coronavirus variant of concern on Friday.
The new strain — initially known as B. 1.1.529 — has triggered a surge in cases in South Africa, with infections also detected in countries such as Australia, the UK, Germany, Israel, Italy and the Czech Republic.
The WHO has said the variant must still be thoroughly studied to assess its danger to the public.
Many nations around the world — including in the Gulf — have taken swift action to safeguard public health and stem the spread of the variant by imposing travel restrictions.