H1N1 Vaccine Protective With 1 Shot


The winter flu vaccine is widely available. Everyone is encouraged to get this one out of the before H1N1 flu shots start arriving in mid-October.

It looks as if only one H1N1 vaccination shot will be needed rather than two as previously projected. This will mean only two flu vaccination shots rather than three. One seasonal flu vaccination and one H1N1 vaccination.

Michael E. Greenberg, M.D and colleagues published online in the New England Journal of Medicine the preliminary results of a phase 2, prospective, randomized, observer-blind, parallel-group clinical trial ongoing in Adelaide, Australia (CMAX, a division of the Institute of Drug Technology).

The study involved 240 healthy, nonpregnant adults between the ages of 18 and 64 years who were randomized into two groups. One received 15 µg and the other group 30 µg of hemagglutinin antigen in a 1:1 ratio.


A single 15-µg or 30-µg dose of the H1N1 vaccine produced a robust immune response in more than 93% of subjects. Seroconversion occurred in 74.2% of subjects. The effect was similar between the two study groups. Protection was noted in most within 10 days of the shot.

This is good news as there was a question of enough H1N1 vaccine being available. Now it looks as if the available vaccine with go more than twice as far. Only one dose and a small dose will be effective.

The U.S. has ordered 195 million doses, based on the hope that 15 micrograms was indeed the right dose.

Flu Information On the Net:
* Flu information: http://www.flu.gov
* National Institute of Allergy & Infectious Diseases

Response after One Dose of a Monovalent Influenza A (H1N1) 2009 Vaccine — Preliminary Report; Michael E. Greenberg, M.D., M.P.H., Michael H. Lai, B.Med.Sc., M.B., B.S., M.Med.Sc., Gunter F. Hartel, M.S., Ph.D., Christine H. Wichems, Ph.D., Charmaine Gittleson, B.Sc., M.B., B.Ch., Jillian Bennet, M.Sc., M.P.H., Gail Dawson, B.Pharm., Wilson Hu, M.D., M.B.A., Connie Leggio, B.Sc., Diane Washington, M.D., and Russell L. Basser, M.B., B.S., M.D., F.R.A.C.P.; published at www.nejm.org September 10, 2009 (10.1056/NEJMoa0907413)

Yang Yang et al. The Transmissibility and Control of Pandemic Influenza A (H1N1) Virus. Science, September 12, 2009


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