People who failed to return for their second coronavirus jab from Monday lose the right to carry a COVID-19 Safe Pass as they are now considered unvaccinated.
In the latest tweaking of the Safe Pass rules, thousands of people who did not get a second jab will be considered unvaccinated and need to take a rapid test, which is free for the vaccinated.
A relevant decree providing for the change came into effect on Monday, the Health Ministry reminded.
The ministry had given people with one jab a chance to get a second shot by 18 October, or their Safe Pass would no longer be valid.
People with only one shot now have to take a coronavirus test every 72 hours.
The ministry said it was prompted to alter the Safe Pass policy as it came to light that 11,000 people did not turn up for a second jab.
In recent weeks, health authorities have frequently reminded the public that receiving only the first dose of a COVID vaccine offers less coverage and is not as effective against more potent variants.
Those who wish to complete their vaccination scheme can visit any walk-in centre for their second shot.
The period between shots for Pfizer recipients is three weeks, four weeks for Moderna and eight for AstraZeneca.
In Cyprus, 81.5% of the adult population received a COVID-19 vaccine, while 79% have completed their vaccination scheme.
As immunity wanes over time, health authorities have rolled out a booster shot scheme to bolster protection against serious disease or death among the elderly and vulnerable groups.
So far, booster shots have been administered to 26,897 people, including health professionals.
To access hospitality, shops or other venues holding more than 10 people at a time, a Safe Pass is required as proof of being vaccinated, recovered from the virus in the past six months or a negative coronavirus test within 72 hours.