The current measles vaccine - administered by an injection - is effective and safe, but experts say coverage could be made better by a vaccine that is easier to administer and transport. Now, a measles vaccine consisting of dry powder that is delivered with a puff of air has proven safe in early human trials and effective in previous animal trials.
Though many people living in the US consider measlesto be a thing of the past - thanks, in large part, to widespread vaccination efforts - the disease has made a comeback in recent years.
In fact, 2014 has so far seen a record number of measles cases in the US, with 603 confirmed cases reported to the Centers for Disease Control and Prevention's (CDC) National Center for Immunization and Respiratory Diseases (NCIRD) between January 1st and October 31st.
The organization says this is the highest number of cases since measles elimination was confirmed in the US in 2000.
Measles is spread by droplets or direct contact with the nose or throat secretions of people who are infected, but it can also be spread through the air or by objects containing nose and throat secretions.
According to the World Health Organization (WHO), measles is "one of the most readily transmitted communicable diseases and probably the best known and most deadly of all childhood rash/fever illnesses."
In 2013, the disease killed 145,700 people worldwide - most of whom were children - despite an already existing effective injectable vaccine.
"Delivering vaccines in the conventional way, with needle injections, poses some serious challenges, especially in resource-poor parts of the world," says Prof. Robert Sievers, author of the latest study from the University of Colorado Boulder's Department of Chemistry and Biochemistry.
New vaccine safe, with evidence of positive immune response
To improve the delivery of the vaccine, Prof. Sievers and his colleagues created a dry delivery technique - that involves an inhalable, dry powder - in order to circumvent the need for injections and liquid storage, and to avoid risk of vaccine contamination.
In previous work, he and his team showed that their vaccine protected rhesus macaques and cotton rats from measles infection, and they also demonstrated that their dry vaccines can be safely stored for 6 months to 4 years at room temperature or in refrigerators kept at 36-46° F (2-8°C).
But their latest study heralds the success of the first phase 1 clinical trial for their vaccine in humans. "Out of an abundance of caution," says Prof. Sievers, "we test first in people who have already had the disease, or been injected earlier by needles with liquid vaccines."
As such, they enrolled 60 adult males aged 18-45 years who were already seropositive for the measles antibody. In the clinical trial, the researchers tested delivery of the powder using two devices and compared those two groups with a group that received the typical injection.
Results showed that the men from all three groups responded similarly and displayed no clinically relevant side effects. What is more, there was also evidence of a positive immune response to vaccination from the powder.
Any adverse events were recorded with diary cards for 28 days after the vaccination, and researchers followed the participants for 180 days post-vaccination to watch for any long-term adverse events. Additionally, the team measured measles antibodies 7 days before vaccination and 21 and 77 days after vaccination.
Commenting on their new dry vaccine, Prof. Sievers says:
"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."
Vaccine trials in humans are ongoing
Though their trial demonstrated that their powder vaccine is safe, because the men were already immune to measles, it could not compare effectiveness of the vaccines.
"It is very good news that we encountered no problems," says Prof. Sievers, "and now we can move on."
He and his team plan to continue their research through phase 2 and 3 trials in people who are not yet immune to measles, including women and children.
The research was funded by a $20 million grant from the Foundation for the National Institutes of Health, with support from the Bill and Melinda Gates Foundation. It should be noted that the authors of the paper include researchers from the Serum Institute of India, Ltd. - the largest manufacturer of childhood vaccines used in developing countries.
Additionally, Prof. Sievers is president and CEO of Aktiv-Dry, LLC, a Colorado-based company that provides dry powder solutions for the vaccine, pharmaceutical and biotechnology industries.