Global Alert and Response (GAR)

Seasonal influenza vaccines and pandemic (H1N1) 2009

30 October 2009

Will current seasonal influenza vaccines offer any protection against pandemic influenza infection?

So far, evidence suggests that current seasonal influenza vaccines will not be protective against pandemic influenza.

On the other hand, will pandemic influenza vaccines protect against other influenza viruses, such as the seasonal influenza?

The pandemic vaccines are not expected to provide protection against other influenza A or B viruses that are different from the pandemic (H1N1) 2009.

Influenza viruses constantly undergo genetic changes and require vaccines that match the circulating influenza strains to be effective, so seasonal influenza vaccines have to be modified annually.

Should people continue to be vaccinated against seasonal influenza?

Yes. Every year many people suffer and die from seasonal influenza, particularly the elderly, children younger than age 2 and people with other medical conditions or weakened immune systems. People should therefore continue to seek seasonal influenza vaccination like any other year.

Can pandemic influenza vaccines be administered with the seasonal influenza vaccine?

Seasonal influenza and pandemic influenza vaccines can be administered together, and there is a public health value in doing so, according to a global panel of immunization experts.

(Updated from 12 July 2009, 27 May 2009 and 2 May 2009 versions)

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