Scientists say they have discovered the first evidence of a “significant” mutation of the coronavirus. The discovery has raised concerns that strides made toward a vaccine so far could become “futile,” according to a new study.

The researchers, who isolated a strain of the virus from a sample collected in India in January, said the mutation appeared to make the bug less able to bind to a receptor on human cells called ACE2, an enzyme found in the lungs.

The discovery of this mutation “raises the alarm that the ongoing vaccine development may become futile in future epidemic if more mutations were identified,” the researchers said, according to Newsweek. The study, which was published on biorxiv.org on Saturday, has not yet been peer-reviewed.

However, the team—led by the National Changhua University of Education in Taiwan in collaboration with Murdoch University in Australia—added that SARS-CoV-2, the virus which causes COVID-19, has a low mutation rate.

“We confirmed that SARS-CoV-2 has a relatively low mutation rate but also proved that novel mutation with varied virulence and immune characteristics have already emerged,” they said.

But Jenna Macciochi, a lecturer in immunology at the University of Sussex who did not work on the study, told Newsweek that although the finding is important to monitor, she doesn’t believe vaccination efforts are hindered. “Small mutations would be expected with any virus. The emerged mutation in this report appears to reduce binding to ACE2 meaning less virulence which could potentially mean less ability to infect. But as this is an isolated report this doesn’t necessarily mean vaccine attempts are futile,” she said.

Benjamin Neuman, professor and chair of biological sciences with Texas A&M University, also told the South China Morning Post that the constant mutation of the coronavirus only means the vaccine will need periodic tests and updates.