The novel coronavirus vaccines are working to stop the highly contagious virus — but not enough people are getting their vaccine shots, experts recently told CNBC.

Do vaccines work well?

William Schaffner, a professor of medicine at the Vanderbilt University School of Medicine, said vaccines don’t work if they’re not used.

  • “Leaving it in the refrigerator doesn’t help, that won’t prevent disease. You have got to move that vaccine into arms,” he said.

Why do you need your shot?

Schaffner told CNBC there are two major questions at hand that researchers need to keep thinking about as they determine the need for booster shots — how long does immunity last? And will variants evade the current vaccines?

  • “The duration of protection of our current vaccines, still to be determined but so far so good, and the other is, whether new variants develop that can evade the protection of our current vaccines,” he told CNBC. “We just have to get (COVID-19 vaccines) more accepted in the population.”

Are unvaccinated people at risk?

Dr. Anthony Fauci, the White House chief medical adviser on the novel coronavirus, said on  the “Today” show earlier in June that unvaccinated people remain most at-risk for variants of coronavirus.

  • “In several weeks or a month or so, it is going to be quite dominant,” he said.
  • He added, “It’s the unvaccinated people that we’re concerned about. ... If they are unvaccinated, they are at risk.”

Surgeon General Vivek Murthy told CNN that unvaccinated people may create more COVID-19 variants, too.

  • “For those who are unvaccinated, they are increasingly at risk as more and more variants develop,” he said.
  • He added, “The news about the delta variant is evidence of really why it’s so important for us to get vaccinated as soon as possible.”