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Experts have estimated that a coronavirus vaccine could take 12 to 18 months before it is available for the public — and without a vaccine, people will still have to maintain some physical distancing measures to keep the virus from spreading, Dr. Tom Frieden, former director of the US Centers for Disease Control and Prevention, said on MSNBC this morning.

"We don't know when a vaccine will come," Frieden told MSNBC Friday.

"Anyone who is not afraid of the devastation this virus causes is not taking it seriously enough and that can be a deadly error," Frieden added. "This is a highly infectious virus. It's spreading like a super SARS — all of the way SARS spread and more."

Due to this, Frieden said the United States could be facing a "new normal."

"What we're going to need to see is a gradual loosening of the faucet. A step wise return to not normal, but a new normal, where no one who is sick goes out, where we stop shaking hands for a while, where we cover our mouth and for a while wear face masks," Frieden said.

Frieden said that while individuals can do a lot to reduce the risk of transmission, people who are vulnerable "are going to have to shelter in place for longer. Maybe not that long, but longer."

On a public health level, Frieden emphasized that people need to get tested when they're at risk and isolate when they're infected. It is also important to track contacts to determine who may have been exposed and quarantine them, Frieden said.

"This is the way we can try to keep the virus at a simmer instead of boiling over," Frieden said.