- The European Union could open up a "Pandora's box" if it restricts exports of Covid vaccines, said James Crabtree of the Lee Kuan Yew School of Public Policy.
- He said the EU is facing "enormous political pressure" to begin to experiment with vaccine nationalism.
- The bloc has already imposed strict rules on exports, including checks on how controlled the receiving country's virus situation is compared to Europe's.
Vaccination drives in the 27-member bloc have been hindered by production issues. Anglo-Swedish firm AstraZeneca earlier this year cut its first-quarter target from 90 million doses to 30 million doses.
The shot, developed in partnership with the University of Oxford, is favored for the vaccine rollout in the European Union.
Officials have already imposed strict rules for exports. The EU will check if the receiving country has the virus under better control than Europe and whether it has limitations on vaccines or raw materials before allowing the shots to be shipped.
Some EU nations, however, have concerns about the new rules and want supply chains to remain open.
European Commission President Ursula von der Leyen is "really struggling" because other rich countries are doing much better on vaccinations compared to the EU, said James Crabtree, an associate professor in practice at Lee Kuan Yew School of Public Policy.
"There's enormous political pressure … to begin to experiment with a kind of vaccine nationalism," Crabtree told CNBC's "Street Signs Asia" on Friday.
"This is, of course, very dangerous because the EU is normally one of the most responsible international actors," he said.
He also warned that other countries may follow the EU's lead in prioritizing vaccines for domestic populations.
"If it begins to try and restrict the flow of vaccines out of EU factories, then it opens up a Pandora's box in which countries like India may then begin to do the same," said Crabtree.
That could be very damaging given that new Covid variants are likely to keep emerging, he added.
For its part, the EU's trade chief, Valdis Dombrovskis, said it is "highly unfair" to accuse the EU of vaccine nationalism, given that it is "one of the largest vaccine exporters."
Data shows that the EU has exported 77 million doses of the shots to 33 countries since December, while 88 million have been delivered to EU countries.
The bloc has also complained that London is not showing the same level of reciprocity in the distribution of vaccines.
Heather Conley of the Center for Strategic and International Studies (CSIS) noted that the U.K. and EU said they are working toward a "reciprocally beneficial relationship."
Still, leaders in Europe are nervous about their political futures with some countries going to the polls in the coming year or so, said Conley, who is director of the Europe, Russia, and Eurasia Program at CSIS.
"Political testiness of leaders and this hysteria about political futures will make the EU take steps that may work ultimately against their long-term interest of getting those vaccines into arms very quickly," she told CNBC's "Squawk Box Asia" on Friday.
"I think the international harm that that would do to global vaccine production would be greater than the increased number of vaccines in the EU," she said.
Experts have long warned that vaccine nationalism could be bad for public health and the economy.
WHO Director-General Tedros Adhanom Ghebreyesus in January said the coronavirus will continue to mutate and thrive if the distribution of vaccines remains inequitable.
"Vaccine nationalism hurts us all and is self-defeating," Tedros said. "But on the flip side, vaccinating equitably saves lives, stabilizes health systems and would lead to a truly global economic recovery that stimulates job creation."
— CNBC's Silvia Amaro, Chloe Taylor and Noah Higgins-Dunn contributed to this report.