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Powdered Measles Vaccine Found Safe in Early Trial
A measles vaccine made of fine dry powder and delivered with a puff of air triggered no adverse effects in early human testing and is likely to be effective, according to an article to be published in the November 28 print edition of Vaccine. The paper is available online.
In 2013, measles killed 145,700 people, most of them children, according to the World Health Organization. That was despite the fact that the conventional injectable vaccine against the measles virus is effective.
“Delivering vaccines in the conventional way, with needle injections, poses some serious challenges, especially in resource-poor parts of the world,” said co-author Dr. Robert Sievers of the University of Colorado–Boulder.
His team developed a dry-delivery technique for the measles vaccine to eliminate the need for injections, liquid storage, and other challenges, such as vaccine contamination. “You don’t need to worry about needles; you don’t need to worry about reconstituting vaccines with clean water; you don’t need to worry about disposal of sharps waste or other vaccine wastage issues; and dry delivery is cheaper,” Sievers said.
The new paper describes the first successful phase I clinical trial of a dry-powder vaccine, he said. Sievers and his co-authors identified no adverse effects of the powdered, inhaled vaccine when tested in healthy men who were immune to measles. In this safety-focused study, the investigators tested delivery of the vaccine with two devices — the PuffHaler (Aktiv-Dry LLC) and Solovent (BD Technologies) — compared with the usual subcutaneous-injection method.
Sixty adult males (18 to 45 years of age), seropositive for measles antibody, were enrolled in the study. Adverse events were recorded with diary cards until day 28 after vaccination, and the subjects were followed for 180 days post-vaccination to assess potential serious long-term adverse events. Measles antibody was measured 7 days before vaccination and at days 21 and 77 after vaccination by ELISA and a plaque-reduction neutralization test.
The men in all three vaccination groups responded similarly, with no clinically relevant adverse effects and with some evidence of a positive immune response to vaccination, Sievers said. Because the men were already immune to measles, the study could not compare the effectiveness of the vaccines, as measured by the subjects’ immune responses. That will be the primary goal of follow-on phase II and phase III pivotal trials, according to Sievers.
“It is very good news that we encountered no problems, and now we can move on,” he said. The next phase of tests could include people who are not yet immune to measles, including women and children.
In preclinical research, Sievers’ team had demonstrated that the powdered vaccine protects monkeys and rats from infection by the measles virus. The researchers also have shown that their dry vaccine can be safely stored for 6 months to 4 years at room temperature or in refrigerators kept at 36 to 46 degrees Fahrenheit (2 to 8 degrees Celsius), respectively.
Sources: University of Colorado–Boulder; November 24, 2014; and Vaccine; November 28, 2014.