Study on nonadjuvented vacccine in China

Chinese H1N1 Vaccine Similar to Western Drugs
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By Michael Smith, North American Correspondent, MedPage Today
Published: October 21, 2009
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner


Action Points
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Explain to interested patients that vaccines developed in the West against the H1N1 pandemic flu appear to give a good immune response with a single dose in most adults.



Note that this study found that a vaccine developed by Chinese researchers was also effective in adults after a single dose.

The pandemic flu vaccine being used in China has characteristics similar to those of vaccines developed in the West, researchers said.

In a randomized trial, the vaccine delivered a dose-dependent immune response that required a single dose in adults, according to Feng-Cai Zhu, MD, of the Jiangsu Provincial Center for Disease Control and Prevention in Nanjing, China, and colleagues.

Children ages 3 to 11, however, required a second dose to reach the same immune response, the researchers said online in the New England Journal of Medicine.

China was first out of the blocks with a vaccine and began immunizing people by the last week of September, but published details have been sketchy. (See Vaccination Under Way Against Pandemic Flu)

In this study, the researchers tested three doses of a split-virus inactivated vaccine in four age cohorts, with and without an alum adjuvant.

The 2,200 volunteers were given two injections three weeks apart. The researchers measured immune responses and safety 21 days after the first shot and 14 days after the second.

The vaccines included 7.5, 15, or 30 micrograms of the viral protein hemagglutinin. The 7.5-microgram vaccine was always delivered with the alum adjuvant, and the others were administered with or without it.

The volunteers were stratified into four age groups -- 61 or older, 18 through 60, 12 through 17, and 3 though 11. The arm including those 18 through 60 was placebo-controlled.

Volunteers were considered to have a protective immune response if antibody titers on the standard hemagglutination inhibition test were at least four times their baseline value.

The researchers found that most volunteers reached an immunogenic response after a single dose of the nonadjuvanted vaccine -- a finding that parallels those seen in vaccines developed in the West. (See H1N1 Vaccines Safe, Immunogenic in Single Dose)

For instance, 97.1% of those 12 through 60 (the same rate for both cohorts) had such a response 21 days after a 15-microgram dose. After the second dose, that rate rose to 100% among the adolescents but there was no change among the adults ages 18 through 60.

At the same time, 97% of the adolescents and 92.6% of the adults had a response from a single 30-microgram dose, which rose to 100% and 98.1%, respectively, after the second dose.

On the other hand, children younger than 12 and those 61 or over had a lower response rate to the first dose of both the 15- and 30-microgram vaccines but after the second dose reached rates comparable to the other groups.

The researchers focused their report on the nonadjuvanted vaccine, because the adjuvanted vaccine delivered lower response rates -- something they said was "consistent" with data from the study of other flu vaccines.

Zhu and colleagues said they saw no severe adverse side effects associated with the vaccine. In the groups getting nonadjuvanted vaccine, 5.5% to 15.9% of volunteers reported mostly mild injection-site or systemic reactions, they said.

The adjuvanted vaccine was associated with a significantly greater number of site reactions (at P<0.001), they said.