And now for some much-needed good news. Scientists who are studying the evolution of COVID-19 say the virus' genetic code appears to be mutating relatively slowly, which suggests a single vaccine could provide long-term protection.

Peter Thielen, a molecular geneticist at the Johns Hopkins University Applied Physics Laboratory, says there are only four to 10 genetic variations between the strains that infected the U.S. population and the strains that emerged from China in late 2019; since then, there have been more than 400,000 confirmed cases of coronavirus around the world.

"That's a relatively small number of mutations for having passed through a large number of people," Thielen told The Washington Post"At this point the mutation rate of the virus would suggest that the vaccine developed for SARS-CoV-2 (the cause of COVID-19) would be a single vaccine, rather than a new vaccine every year like the flu vaccine."

Thielen explains that a virus' genome will undergo changes (or mutations) over time, as "they replicate imperfectly inside a host's cells and then spread through a population." Sometimes these mutations can be so rapid that the viruses require a new vaccine every year, which is the case for influenza. But this doesn't seem to be the case for coronavirus. Thielen says the COVID-19 mutation rate is slow that it's likely a single vaccine could provide immunity for a long period of time. He compared the potential vaccine to the ones used for chickenpox and measles.

"I would expect a vaccine for coronavirus would have a similar profile to those vaccines," he said. "It's great news."

Researchers are urgently pursuing a COVID-19 vaccine as the deadly virus continues to spread in certain regions of the world. However, Mike Ryan, executive director of WHO's health emergencies program, told the BBC that such a vaccine would not be available for at least a year.

"I think we have to be realistic. Vaccines take a lot of time to develop, test, make them safe, prove they’re effective, then you need to produce enough vaccines for everybody," Ryan explained. "We have to make sure that it’s absolutely safe … we are talking at least a year."

In the meantime, Ryan says governments need to implement measures that would slow the spread of COVID-19. This could include lockdowns or shelter-in-place orders.

"If we don’t put in place the strong measures, the strong public health measures now, when those restrictions and those movement restrictions and lockdowns are lifted, the danger is the disease will jump back up," he said.

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