Children across Canada continue to be a target for the contagious measles virus, but a growing number of adults who were never immunized, or received only one dose of the vaccine, are being infected, too.
Now, some doctors are sounding the alarm on the need for a national vaccine registry – in addition to existing provincial databases – that would track Canadians, newcomers to the country, and those who have travelled to measles trouble spots such as the Netherlands and Philippines. "Here in Ottawa, we have a provincial data base [that tracks who has been immunized and when]. It's very useful and a big step in the right direction," said Dr. Rosamund Lewis, associate medical officer of health for Ottawa Public Health. But, she said, "we need a national registry."
Such a registry would streamline contact between provincial health organizations and the federal government, ensure medical histories are available for doctors when they need it, and allow for fast identification of individuals who are not fully vaccinated.
"Health care is meant to be portable," Dr. Lewis said. "When we move from province to province, we don't necessarily carry our medical records with us."
The precise number of adults who have contracted measles has not been made public. B.C.'s Fraser Valley has 228 cases, the majority of which are minors. (On Sunday, an official with Whatcom County, Wash., reported that an American resident had contracted the disease in B.C., but health authorities would not release the age of the patient.) Alberta Health Services said that of the 50 cases it has encountered in 2013-14, nine involved adults 20 years and older. Of Ottawa's four cases, one is an adult male, and in Manitoba two adult males have the disease. An un-immunized university student was diagnosed with measles in the Waterloo region last week.
The latest report of potential measles exposure in Ontario comes from Mississauga, where public health officials have warned that a man from Hamilton, Ont. who visited the Sky Zone Indoor Trampoline Park on March 22 has been diagnosed with measles.
Dr. Allison McGeer, an infectious disease expert at the University of Toronto, says a vaccination registry solves a number of problems, but wouldn't be without pitfalls of its own.
"All of us have trouble remembering our vaccination histories – especially when it gets to be 30 or 40 years ago. The paper vaccination cards are great, but it is easy to forget to take them when you get a vaccine, and they are relatively easy to lose. Mothers sometimes forget, and family physicians move and retire, and their records are not kept forever. So when people end up being exposed to, say, measles, and need to know whether or not they are immune (which might determine whether they need treatment, or have to be off work), it can be difficult to find out," she explained.
Furthermore, a national registry would streamline the flow of information when families move to a new city or province, as getting immunization cards to a new physician and transcribed into their records is difficult and error prone.
"A vaccination registry would fix all that," she said.
But, Dr. McGeer added, Canada has struggled with creating information systems that securely store private information.
"Registries also raise substantial issues of privacy and confidentiality … Setting up a system in which vaccine providers can enter vaccine data when you need them to, but not access information that is private to you, and have the information protected from hackers, has been a challenge that has so far defeated us in Canada," she said.
To be considered 100 per cent vaccinated, Canadians need two doses of the measles, mumps and rubella vaccine. Without full protection, Canadians who travel abroad may be susceptible to measles in countries where the immunization rates are low.
"Any time you've got a measles outbreak in a different part of the world, you've got a concern," said Dr. Michael Routledge, Manitoba's chief public health officer.
On the flip side, immigrants moving to Canada may not have been vaccinated at all. According to the Public Health Agency of Canada, "persons newly arrived in Canada lacking adequate documentation of immunization should be considered unimmunized and started on an immunization schedule …"
"We've done a pretty good job with the bulk of the people. But there are lingering concerns," Dr. Routledge said. "There are some religious groups (opposed to vaccinations). In Canada, and Manitoba, we have a lot of new Canadians and sometimes they don't have the same immunizations we do."
With a report from The Canadian Press