State health officials, continuing to investigate the growing number of mumps infections statewide, are urging most Hawaii residents to get an extra mumps vaccination.

On Friday, the Department of Health notified primary care physicians, emergency and urgent care doctors and nurse practitioners of a new recommendation for an additional mumps vaccination due to an outbreak that has grown to 384 cases so far this year. Most of the cases have been on Oahu.

“We sent it out to the physicians because what we didn’t want to have is everyone rushing out to the pharmacies,” said State Epidemiologist Dr. Sarah Park. “We want to try to make sure we’re focused on people who especially live or work in crowded conditions.”

That includes multigenerational households and workplaces where people are typically 3 to 6 feet away from each other at any given time, she said.

“That’s kind of where we’re seeing more of the cases. More often than not, people who are in those situations — having larger numbers of members in one’s household — can potentially put you at higher risk,” she said. “Especially because of our culture, we naturally share things. We’re very open with each other.”

Mumps, a contagious viral disease, is spread from coughing, sneezing and touching infected items, such as cups and utensils. The state has confirmed the disease in both vaccinated and unvaccinated children and adults. Most of the cases — nearly 60 percent — have been in adults 18 years and older.

“The number of cases seems to be increasing so it seems reasonable that people should get an extra dose particularly if they hadn’t had the vaccine in a long time,” said Dr. James Ireland, a community physician. “Oahu is generally a crowded place and there’s potential exposures in schools, workplaces and even on the street when there’s enough people around.”

The current routine is that children get two doses of the measles, mumps and rubella vaccine, known as MMR. Adults born in 1957 or later who had two doses of the vaccine 10 or more years ago should get a third vaccination, while those with one dose five years or more ago should receive a second dose. Adults born before 1957 when mumps was prevalent have likely been exposed to the disease. People who do not know if they had the disease or were ever vaccinated should also get the shot immediately, the DOH recommends.

“It really gets down to how is that saliva spread,” Park said. “From looking at data from other outbreaks, there may be some element of waning immunity. Like so many other disease numbers we report, it’s only part of the story. There are probably many more we haven’t detected. We strongly encourage people to consider it (getting the shot) in consultation with their health care provider.”

Though not ideal, receiving extra doses of the vaccine generally poses no health risk, the department said.

Symptoms of mumps resemble the flu and include fever, headache, fatigue and loss of appetite. The main symptom of the disease is swollen salivary glands near the jaw.