The World Health Organization says that its panel has concluded that vaccinations against the novel coronavirus should not be mandatory for international travelers, citing uncertainty over effectiveness and supply.

“Given that the impact of vaccines in reducing transmission is yet unknown, and the current availability of vaccines is too limited, the committee recommended that countries do not require proof of vaccination from incoming travelers,” the WHO Emergency Committee said in a press release.

The committee called on countries to “implement coordinated, time-limited, risk-based, and evidence-based approaches for health measures in relation to international traffic in line with WHO guidance,” it said.

The announcement comes as many countries scramble to strengthen border controls and require incoming travelers to submit proof of having tested negative for the coronavirus before departing from their countries.

Earlier this week, the U.S. government said it will require from Jan. 26 all overseas travelers to provide proof of a negative coronavirus test result before they are permitted to board inbound flights.

The committee “strongly encouraged vaccine manufacturers to rapidly provide safety and efficacy data” to the WHO, the release said, noting that the lack of such data may become a barrier to ensuring a timely and equitable supply of vaccines around the world.

While vaccination against the coronavirus is under way in some countries, access has mainly been limited to the elderly and workers in selected occupations such as medical personnel, police officers and nursing care facility staff members.

It is expected to take some time before the general public will receive the vaccinations on a wide scale.

-Agencies