LONG BEACH, N.Y. (CBSNewYork) — Despite a widely administered vaccine, there has been an outbreak of mumps on Long Island. There are 18 people, most in their 20s and 30s, recovering from the contagious virus.

As CBS2’s Carolyn Gusoff reported, most Americans under age 45 have been vaccinated — so why an outbreak now? Health officials said it could be a new strain that’s not covered by the MMR — measles, mumps, rubella — vaccine.

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Restaurants in Long Beach have been putting all of their glasses into a high temperature dishwasher, and supplying plastic cups — protective measures to stop a mumps outbreak.

Keegan Travers said several of his close friends have gotten it.

“I thought it was completely wiped out, weird,” Travers said.

Officials have asked anyone who knows they are sick to stay home.

“If you know you’re sick please stay home and don’t transmit this. Mumps is transmitted through saliva,” Dr. Lawrence Eisenstein, Nassau County Health Commissioner said.

The commissioner warned that the virus is making a comeback in Long Beach and nearby south shore communities where most of the victims were vaccinated. The virus was all but wiped out after the vaccine became standard issue in the early 70s, so this could be a new strain.

“It is highly contagious, and even those who were vaccinated can get mumps,” Dr. Aaron Glatt said.

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Doctors at South Nassau Communities Hospital said some presented with tell-tale swollen cheeks, but also less obvious symptoms.

“They are very non-specific. You can come in with just a headache, a low grade fever, body aches, similar to the common cold,” Dr. Joshua Kugler said.

In worst cases mumps even cause deafness, male sterility, and brain inflammation. That’s why officials have warned against sharing drinks, food, and utensils, and suggested washing hands often.

If you have symptoms, stay home for at least five days after onset.

There is no cure, only supportive treatment.

At the height of beach season, Long Beach officials say ‘be aware.’

“Everybody should come down and enjoy the summer, there’s no cause of over alarm,” Long Beach City Manager Jack Schnirman said.

For the most protection you need two doses of the vaccine, and some people may have only gotten one.

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The health department said it’s never too late to get a booster shot. It’s especially advisable if you think you’ve been exposed to someone with mumps.