Flu expert urges pre-vaccination against possible pandemic strains

TORONTO — A leading figure in the world of flu is making a bold proposal on how to circumvent too-slow production and too-little output of influenza vaccine during a pandemic.

Dr. Klaus Stohr, former head of the World Health Organization's global influenza program, is suggesting the world consider pre-vaccinating people, giving them protection against strains that could emerge from nature to trigger future pandemics.

In an opinion piece published Thursday in the journal Nature, Stohr argues pre-pandemic immunization may be one of the few solutions to a vexing problem — there is no way to make pandemic vaccine fast enough and in large enough quantities when it is needed to have an impact on the toll the outbreak takes.

Stohr is now vice-president of influenza strategy for Novartis Vaccines and Diagnostics, the world's No. 2 flu vaccine producer and a company which stands to gain significantly if his proposal were to take off.

Still, he insisted that he — not Novartis — is making the proposal because the pandemic response model needs to be fixed and the available options are limited.

"I'm not saying it's simple. I'm not saying it's inexpensive. I'm only saying that there is no other solution I can see," Stohr said in an interview Wednesday.

"We need a game changer."

Stohr's proposal, which has been floating around flu circles for years, is to use vaccine between pandemics to build up at least partial immunity against some or all of the potential virus subtypes that could cause a pandemic.

There are 16 types of hemagglutinins, which is the H in a flu virus's name. The hemagglutinin is the protein on a flu virus's surface that latches onto cells the virus is invading; it is the portion of the virus the vaccine teaches the immune system to target.

Adding vaccine against an H7 or an H9 or an H5 virus to a seasonal flu shot could start to build up some immunity to those viruses in the human population, Stohr argues.

But given the range of virus subtypes that exist and science's inability to predict which will ever be a threat to humans, Stohr's idea would require millions and eventually billions of people to be vaccinated against viruses they might never encounter in their lifetimes.

A fellow flu expert, Dr. Michael Osterholm, shares the view the system needs to be fixed. The experience with H1N1 — where even countries that had pre-purchased vaccine only started to get substantial supplies after the second wave had peaked — is proof a major overhaul is needed, said Osterholm, who heads the Center for Infectious Diseases Research and Policy at the University of Minnesota.

"What this demonstrated was that much of the hopes and dreams that we had for influenza vaccines for a pandemic were just those — they were hopes and dreams. When it came to the actual plan, the execution of that plan and the delivery of timely vaccine, it didn't happen," he said.

But Osterholm doesn't believe Stohr's proposal is the answer. For one thing, he said, most countries that had H1N1 vaccine couldn't persuade even a third of their citizens to take the shot. Poor uptake even in the midst of an outbreak throws into doubt how willing people would be to get vaccinated against viruses they might never encounter.

"The idea that we could somehow go out and vaccinate large populations with vaccine in a pre-priming environment — particularly with adjuvants, which were shown throughout the course of this pandemic to be a deterrent to people receiving vaccine because of safety concerns — is just way off the mark," Osterholm said.

Adjuvants are compounds which boost the immune response to vaccine, stretching supplies by allowing lower doses to be used. While they have been used in flu vaccines for seniors in Europe for years, adjuvants are new to many countries. And in countries, like Canada, that bought adjuvanted H1N1 vaccine, some people refused the shots because of concern over the safety of adjuvants.

Osterholm also argued that pre-vaccinating might not offer much benefit. H1N1 viruses have been circulating for most of the last century and most people alive have some immunity to them, yet an H1N1 virus from pigs was sufficiently different that it was able to cause a pandemic, he noted.

"Even if you had a similar subtype vaccine, there's no guarantee whatsoever there'd be any protection against a similar subtype that emerges as the pandemic strain," Osterholm said.

"It's like picking one Donald Paul Peterson out of the Minneapolis phone book assuming that represents every Donald Peterson in Minnesota."

Stohr countered that the mildness of the H1N1 pandemic actually proves the value of his proposal, suggesting the reason the outbreak was so mild was because so many people had antibodies to distantly related H1N1 viruses.

There are other issues that stand in the way of Stohr's proposal, global production capacity and the lack of public health infrastructure in many countries among them.

In the end, he acknowledged, his idea may not be the best option. But critics should come up with alternatives, he said, because the time to improve the system is now.

"We need here global leadership to put the best people around a table and come up with doable things," Stohr said.

"It's provocative, it's radical," he admitted. "And some people will throw up their hands and say this is totally impossible. But we need solutions and we need discussion about it and we need something practical."

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