Life-saving vaccines have to be refrigerated before use to guarantee their effectiveness – a necessity that has made it difficult to deliver vaccines to remote areas. Professionals have even used drones as a quick delivery method. However, a new approach may change all this. Researchers at McMaster University say they have developed a method to store vaccines in a cheap and safe way at more than room temperature for up to three months without losing effectiveness.
Presented in Scientific Reports, the researchers were able to combine the vaccines' active ingredients with sugars, creating doses that are light, durable, compact, and able to withstand high temperatures for up to eight weeks. The sugars in question are called pullulan and trehalose, which are FDA-approved and have been studied as a coating for fruit and vegetables to extend their shelf-life.
Vaccines need to be kept at between 2°C and 8°C (35°F and 46°F). This means that infrastructures have to be in place to make sure the inoculation remains viable from its production all the way to the person injected with the vaccine. Many regions, mostly hard to reach and/or poor, don’t have those structures in place, costing people their lives.
Several methods have been put forward to create vaccines that are unaffected by temperature changes, but this one appears to be relatively simple: the viruses are dried in a sugar film made from pullulan and trehalose. This helps to stabilize the enzymes and viruses by protecting them against oxidation and high temperatures. Once dried, the team capped the tubes, wrapped it in paraffin film, and put it in a heating block at 40°C (104°F) for up to 3 months. Once needed, the vaccine is reactivated with water and returned to its original form. The team tested the approach in mice with two sample vaccines, the flu vaccine and the herpes simplex vaccine, and they remained effective.
"You can spend all kinds of money developing a vaccine, but if it is deactivated by high temperature an hour before you can give it to someone, it doesn't matter," co-author Ali Ashkar, a professor of Pathology and Molecular Medicine specializing in immunology at McMaster University, said in a statement.
The researchers noted that encapsulating vaccines in sugar adds a marginal cost to the manufacturing side of things while dramatically reducing the cost of transport and storage. Given that the latter is 80 percent of the total cost, this method is cheaper in the long run.
"This, to us, is the ultimate application of this technology," said lead author Vincent Leung, an assistant professor of Chemical Engineering also at McMaster. "To imagine that something we worked on in the lab could one day be used to save people's lives is very exciting."
The researchers are now working to take the method to market.