The latest case of the measles in the Lower Mainland involves someone who became infected even though they’ve been vaccinated.

On Friday, a medical health officer with Vancouver Coastal Health said it has been confirmed the individual had one dose of the measles, mumps and rubella (MMR) vaccine when they were a child.

Health officials stressed it is important to receive two doses in order to be fully protected.

“From 1970 to 1994, we were only giving one dose of measles-containing vaccine in the routine immunization at the time. We realized in the mid-90s that it was important to have two doses to protect people,” Dr. John Harding explained.

The individual didn’t show symptoms for a few days and later and went to several crowded places between Saturday and Tuesday, including the Skookum Music Festival, a community block party on Quebec Street and the Noodlebox restaurant in Mount Pleasant. They also rode the Main Street bus from Terminal to Broadway.

A full list of locations and times of concern is available here.

“Measles is highly infectious. It’s a virus that stays active in the area for up to two hours after a person has left,” Harding explained.

Adults 'complacent' about vaccinations: researchers

A policy analyst with C.D. Howe Institute said it’s common for adults to be unaware of their immunization status.

“We are very conscientious of our children getting their vaccines but we can become complacent in adulthood because it isn’t part of regular conversation,” Rosalie Wyonch said.

Wyonch said “anti-vaxxers” are just a minority of the population and most those who don’t get immunized tend to be complacent and what she calls “vaccine fence-sitters.”

“They may not be well-informed about the risks of not getting a vaccine they may not be well-informed about whether there are risks in getting the vaccine, and so they simply don’t know if they should get it,” she said.

Health officials said for those who aren't aware of whether they received just one dose of the MMR vaccine or the full amount, it would not be harmful to get the booster shot.

People are encouraged to go to their doctor’s office, pharmacy or community health centre to get a free vaccine.

To learn more, people are asked to call VCH Public Health (604-675-3900).