As Ontario and Quebec grapple with measles outbreaks, Liberal Leader Justin Trudeau has been attacking the Prime Minister’s record on vaccines during question period this week.

On Tuesday, Trudeau slammed Stephen Harper for running “partisan government ads” instead of a public health campaign to encourage parents to vaccinate their children. Trudeau went on to accuse the government of cutting the Public Health Agency of Canada’s budget for immunization programs by 23 per cent since 2006-07.

All the parties, of course, agree that vaccines are essential to public health. Harper said as much in his retort: “The minister of Health always advocates the use of vaccines. Vaccines have historically proven effective in improving the health of our children and families . . . As for the ads, we have a responsibility to make Canadians aware of all government measures, and we will continue to do so,” he said.

On Wednesday, Harper challenged Trudeau’s statement that the immunization budget has been cut by 23 per cent. “I checked on those numbers overnight, and saw that there had been no reduction whatsoever,” he said.

Here’s a quick fact-check of the Prime Minister’s fact-check: In the public health agency’s 2006-07 “report on plans and priorities,” $10 million is budgeted for immunization. In the 2013-14 version of the same document (scroll down to “Sub-Sub-Program 1.2.1.1: Immunization), the budget is $7.69 million—a reduction of 23.1 per cent.

However, this tells us nothing about the real amount spent on vaccination, which may be the source of the discrepancy between the numbers put forward by Trudeau and Harper. In the past, actual money used for immunization initiatives has fallen short of allotted funds. (The partially abandoned national vaccination registry is an example. Of the $135 million budgeted for the project in 2007, only 97 million was reportedly spent by last year).

The Public Health Agency of Canada’s publicly available spending reports aren’t broken down by program. However, a spokesperson told us that overall government spending on immunization has been stable over the past ten years if you count Health Canada funding, Public Health Agency of Canada funding, and special projects such as the new immunization records app.

“Health Canada and Public Health Agency of Canada funding for immunization since 2005 has ranged from over $15M a year to over $20M in 2010-11 on the heels of the H1N1 pandemic in Canada. Planned spending for fiscal 2014-15 is approximately $18M,” the spokesperson wrote in an email.

Some commenters have pointed to an audit the agency did of its immunization program in 2012 as the possible origin of budget cuts specific to PHAC. The document says that the effectiveness of the agency’s programs promoting vaccination—such as National Immunization Awareness Week and the Canadian Immunization Conference—has never been evaluated. The report concluded there was “no evidence” that the awareness campaigns were having any effect at all.

The audit also draws attention to Canada’s tangle of territorial, provincial and national health authorities and the confusion that can create: “The absence of a clearly defined and communicated mandate . . . has contributed to a lack of clarity among external stakeholders on the Agency’s purpose and intended roles . . . This constitutes a potential risk to the Agency’s reputation.”

Health Minister Rona Ambrose has been continually reassuring the public that Canada’s vaccination coverage rates are at a healthy 95 per cent, high enough to prevent large outbreaks through herd immunity, a number that comes from a 2011-12 telephone survey covering 3,000 children. At that time, 95 per cent of parents said their kids’ immunizations were up-to-date. Parents of kids aged two, seven, and 17 years were polled.

An updated edition of the survey taken in 2013 and 2014 is due out soon. According to Dr. John Spika, the director general for immunization at the Public Health Agency of Canada, it will be an improvement over past versions. More households were surveyed, and the data will be broken down by province for the first time. There will also be an effort to check parents’ responses against available information about kids’ vaccinations.

Still, as Maclean’s reported last week, there’s limited evidence that any campaigns are effective at dissuading anti-vaccination parents. And in many cases, those most vulnerable to vaccine-preventable diseases are not children, but adults, because they may not have received enough doses of vaccine or their immunity may have worn off.