The H1N1 pandemic vaccines are expected to confer 'good protection,' the WHO said. (Darren Calabrese/Canadian Press)

The World Health Organization says millions of doses of H1N1 vaccine have been given so far and no unusual side-effects have been seen.

Dr. Keiji Fukuda, the agency's top flu expert, told a news conference in Geneva on Thursday that 20 countries have started to administer the pandemic vaccine, which appears to be "very safe."

He said the rates of local reactions like sore arms are similar and maybe even lower than seen with seasonal flu shots.

Fukuda added that H1N1 viruses still aren't mutating much, though the WHO expects they will start to as immunity in the human population rises.

He said cases of viruses that are resistant to the antiviral drug Tamiflu remain isolated and sporadic.

"We see no evidence at all that there is widespread occurrence of antiviral resistance," Fukuda told reporters.

Fukuda also said H1N1 viruses are the dominant flu viruses all over, and appear to be starting to crowd out H3N2 viruses in East Asia.

Vaccine costs in Canada

Meanwhile on Wednesday, the federal government's 2009-10 supplementary estimates suggested it will cost Ottawa and the provinces $400 million for the H1N1 vaccine, not including related costs.

The federal government is covering 60 per cent of the cost for 50.4 million doses, while the provinces and territories will foot the rest of the bill. The government ordered the total before it was clear whether people would require one shot or two.

The estimates were tabled Wednesday by Treasury Board president Vic Toews.

Ottawa will spend $78 million more on related costs incurred by Health Canada, the Public Health Agency of Canada and the Canadian Food Inspection Agency. As well, the government's public awareness campaign cost $4.5 million.