Making vaccine for new flu H7N9 flu virus could be a challenge, experts say

TORONTO – Influenza experts say making a vaccine to protect against the new H7N9 flu virus that has emerged in eastern China could prove to be problematic.

In an article published online in the New England Journal of Medicine, experts from the U.S. Centers for Disease Control warn that previous clinical trials with H7 vaccines suggest they induce a poor response in people.

The head of the CDC’s influenza division says this may mean producing a workable vaccine for this virus, if it is needed, could be challenging.

But virologist Nancy Cox says those fears would need to be confirmed in research with this particular H7 virus.

Another influenza expert, Michael Osterholm, says the earlier studies show that even when people get 12 times the amount of vaccine they would get for a seasonal flu virus, H7 vaccines don’t trigger production of many protective antibodies in healthy adults.

And he warns that if a vaccine doesn’t work well in that group, it’s likely to work even less well in older or sicker people.

“If you add all those (facts) together, it doesn’t really paint a really very optimistic picture about influenza vaccine being a really significant weapon against this, should a pandemic emerge quickly,” Osterholm says.

Since it reported the first three human cases of this flu at the end of March, China has confirmed 38 infections and 10 deaths. Laboratories in a number of countries are working to develop the seed strain for a vaccine so that it will be ready if countries decide to order H7N9 vaccine.