China recently announced it will make it easier for foreign travelers to apply for a visa to enter the country if they've received one of the Chinese-made COVID-19 vaccines.

"The final target of every country is to get rid of the coronavirus pandemic and gradually recover economically. In this context, if we want to get back to normal and facilitate people's  traveling, we indeed need such kind of policies," said Hu Naijun, associate professor at the School of Public Policy and Management of University of Chinese Academy of Sciences. 

But the move has also raised concerns, as China prioritizes its domestic jabs over those approved by the World Health Organization.

"It's quite acceptable, because a country has confidence in its own-made shots. It knows the efficacy of its vaccines so it can facilitate the process of people entering the mainland," said Alice Hyun-Kyung Tan, an internist at MizMedi Women's Hospital in Seoul.

Countries around the world are weighing measures to ease cross-border travel restrictions, by rolling out so-called vaccine passports, which will open up international travel for people who have been vaccinated. But experts believe for some regions, rushing the policy through could be a mistake.

"In many European countries, as we know, some are already in lockdown... and some are preparing to lockdown... so I believe it's indeed not a good time for them to open the borders," said Tan.

Experts say the policy of vaccine passports could also put stresses on global vaccine supplies, which are already unequal, with many poorer countries unable to access jabs at all.

"I think currently we need first tackle the problems of the lack of COVID-19 vaccines... so more people can get vaccinated," added Tan.

Experts say the vaccine passport is nothing new. In the past, authorities have put forward this kind of passport for yellow fever. But since COVID-19 is a brand new disease, COVID-19 vaccines are also brand new.

"Usually if we issue a vaccine passport, there would be an expiration date for it. The problem with COVID-19 vaccines is we do not know the durability of immunity provided by the vaccines, so we cannot decide the expiration date of the document," said Tan.