But this week a Chinese pharmaceutical company announced it is getting closer to developing a homegrown mRNA vaccine, which may prove a critical step in Beijing accepting the technology, providing a much-needed immunity boost to its 1.4 billion population, and finally reopening its borders.

On Monday, Chinese vaccine maker Walvax Biotech published Phase I clinical data on China’s first homegrown mRNA vaccine showing that the vaccine induced an immune response. Walvax is jointly developing the vaccine with private vaccine maker Suzhou Abogen Biosciences and the Chinese military’s Academy of Military Science, and published the peer-reviewed study in The Lancet medical journal.

In the study, Walvax gave six different groups of 20 people two jabs 28 days apart. One group received a placebo, while the other groups received differing doses—5, 10, 15, 20, or 25 micrograms—of the vaccine to gauge the intensity of immune responses.

The results showed the mRNA jab has an efficacy between 80% and 95%, which is on par with the mRNA vaccine developed by Pfizer and BioNTech—but Bloomberg Intelligence analyst Mia He says those early figures don’t tell the whole story.

For one, He told Bloomberg, the Walvax vaccine appears to be more effective in generating antibodies than actually catching the virus when administered in certain concentrations. That finding suggests that unless dosing is extremely precise, getting the jab may not provide more protection than getting COVID-19. Other mRNA vaccines, like BioNTech’s, don’t have that problem.

Plus, the Walvax vaccine appears to cause more side effects, such as fevers, than Pfizer’s or Moderna’s shots do. But the study remains the first clinical proof that China may have a viable homegrown mRNA jab to distribute to its population.

Chinese authorities, meanwhile, appear to have iced out the country’s other mRNA option: the BioNTech jab.

Since March 2020, China’s Fosun Pharma has partnered with Germany’s BioNTech to market and distribute the proven and highly effective mRNA jab in the Chinese market. (Pfizer, which struck an agreement with BioNTech after Fosun did, controls distribution rights to BioNTech’s vaccine in most other countries.)

Fosun Pharma has already distributed jabs to places where it controls distribution rights, including Hong Kong, Macau, and Taiwan, and has reportedly built manufacturing facilities to produce the mRNA vaccine in mainland China.

But Beijing has yet to approve the vaccine for distribution in mainland China, despite BioNTech’s mRNA shot being more effective than the inactivated vaccines from makers like Sinopharm and Sinovac that China is currently distributing to its citizens.

Last July, when Walvax’s drug was still in development, the company’s director of research development, Dr. Tong Xin, told Fortune he was optimistic that an mRNA jab would eventually launch in China because “the vaccine technology has been proved effective.” But Walvax still has a long way to go before it can bring its drug to market.

Walvax reports it is currently conducting Phase III clinical trial for its vaccine in Mexico and Indonesia, but it is still recruiting the volunteers it needs to carry out the tests. Finding volunteers is increasingly difficult as global vaccination rates have increased since the pandemic began. The trial requires unvaccinated test subjects.

The stakes may be high for Walvax to complete its trials soon and begin rolling out the jabs.

On Wednesday, Bloomberg reported that Hong Kong’s European Chamber of Commerce expects mainland China—and Hong Kong by proxy—to remain closed off from the world until the country starts administering an mRNA vaccine as a booster to its 1.4 billion citizens. The chamber believes that China may only feel confident in opening its borders once citizens can get boosted with more effective mRNA vaccines.

But the chamber said it expects that process of boosting citizens with mRNA shots to take up to two years, with China and Hong Kong potentially remaining closed until the spring of 2024.