Expert from Seattle’s PATH comments on one-shot H1N1 “swine” flu vaccination studies

It may be possible to protect most people from the new H1N1 “swine” flu with just one shot instead of the two shots many experts thought would be needed, writes Dr. Kathleen Neuzil, director of the Influenza Vaccine Project at Seattle’s global health organization PATH, in an editorial published online by the New England Journal of Medicine.

Dr. Neuzil’s editorial commented on two preliminary vaccine studies also published by the journal online that reported strong immune responses to the virus in people after just one shot.

Health officials have been concerned that if two shots were needed to get a strong immune response it would be much more difficult to slow the epidemic, which is already well underway in some parts of the U.S.

First, is hard enough to get people to come in to get one shot, let alone two shots. If two-shots were required, officials feared many people would fail to return for the second shot needed for full vaccination.

Second, a two-shot regimen requires twice as much vaccine, which is in short supply. If a one-shot regimen proves to be sufficient, the world’s vaccine supply will essentially double.

On the basis of the findings of these two new studies, Dr. Neuzil says in her editorial, “it would be appropriate to begin vaccination with the use of one dose….”

However, Dr. Neuzil have some caveats: first, the study participants were healthy, younger adults, and the vaccines tested in these studies may not work as well in younger children, the elderly and people with chronic illnesses.

Additional studies are underway to determine whether these groups need additional doses and to evaluate the effectiveness of different formulations of the vaccine, Dr. Neuzil pointed out, but “…The desire of see all the available data must be balanced with the need to deploy vaccine quickly to reduce morbidity associated with the pandemic.”

To learn more:

• Read the two research articles here and here (articles are free to the public).
• Read Dr. Neuzil’s editorial.
• Visit the U.S. Centers for Disease Control (CDC) and Prevention’s Web page on H1N1 flu.
• Visit the Web page of PATH’s Influenza Project.

Category: Influenza