A passenger who had measles while travelling on an Air China flight from Beijing to Vancouver on March 3 may have put other passengers at risk, says Vancouver Coastal Health. 

Air China flight 991 arrived in Vancouver at 9:30 a.m. PT, March 3.

The health authority said the infected passenger developed symptoms after arriving in Vancouver, but would have been infectious during the flight. â€‹People are infectious from four days before to four days after the onset of the rash.

"Because flights from Beijing to Vancouver are long, and because measles is the most infectious disease known to us, when we can, we take the opportunity to tell the public they've been exposed," said Dr. Reka Gustafson, a medical health officer with Vancouver Coastal Health. 

Gustafson says people who have been exposed to measles can mitigate the risk of infection by getting immunized — if they're not already â€” within six days of exposure. Because it's now been more than a week since the flight arrived, passengers should watch for symptoms and can isolate themselves to prevent further transmission if they confirm they are infected. 

Measles symptoms include:

  • Fever.
  • Cough.
  • Runny nose.
  • Conjunctivitis, or pink eye.
  • A red rash.

Gustafson says the passenger didn't know they were infected when they got on the flight, and says they weren't immunized because a health condition prevented them from being vaccinated. Vancouver Coastal Health is not releasing information about the passenger's nationality, age or gender.

VCH is taking this opportunity to remind those who may have been exposed, as well as the general public, to ensure they're up-to-date with their measles vaccinations.

It's also reminding the public that measles is highly infectious and can lead to serious complications, even death.  

In April 2015 two passengers aboard a flight from Beijing to Vancouver travelled while they were infectious. At least 11 people were infected as a result. 

"In that particular case the individual was very sick on the plane and highly symptomatic, and had a strong cough, which actually increases infectiousness on the plane," Gustafson said. 

The chances of exposure are less likely in this case, she says, because the infected person was much less symptomatic.

Most B.C. residents have been immunized with the measles, mumps and rubella vaccine, but may not be if they were born outside of Canada.

The health authority says people need two doses of the vaccine to be fully immunized.

It says those born between 1957 and 1970 have probably already had one dose but may need another, while those born after 1970 are likely fully immunized.

People born before 1957, or who have had measles before, are considered immune. 

However the health authority says those observations only apply to people born in B.C.