Vaccines that Can Beat the Heat
A new process could keep vaccines stable at tropical temperatures.
Mixing virus-based vaccines with sugars and allowing them to dry on a simple filter can keep them stable for four months, even at tropical temperatures. The process, developed and tested by scientists at Nova Bio-Pharma Technologies and the University of Oxford, could provide an inexpensive way to streamline vaccine storage and delivery, reduce waste, and improve vaccine efficacy. “It is very simple,” says Matt Cottingham, a virologist who worked on the project at Oxford.
The new technique could make vaccines cheaper and more accessible in areas lacking modern infrastructure. Existing live vaccines must be refrigerated between 4 °C to 8 °C to remain effective. In countries like England and the United States, maintaining this “cold chain” costs up to $200 million a year and increases the cost of vaccination by 14 percent to 20 percent, according to the World Health Organization. In poor countries, the refrigerated transports and even electricity at medical clinics is often missing altogether, making vaccination impossible.
Nova has previously shown that the technique can stabilize various types of vaccines, as well as protein-based drugs. The new study, published in today’s issue of Science Translational Medicine, is the first time a live-virus vaccine has been kept potent after exposure to high temperatures.
The scientists used the technique on two viruses that are the basis for some of the latest vaccines in development. To make vaccines from these live viruses, the researchers disable the viruses so they can infect a cell in the body but not replicate, and then engineer them to carry genes for proteins from different disease organisms. This way, the viral vaccine will stimulate an immune response but won’t make the recipient sick. The team at the Jenner Institute in Oxford, led by professor Adrian Hill, has pioneered the use of these viruses as the basis for vaccines against tuberculosis, malaria, and a “universal” flu vaccine, as well as for HIV. All of these are currently in clinical trials.
The viruses must remain alive in order to be effective, but they are sensitive to heat. Drying them in the sugar solution makes them less vulnerable. “This could be a really big breakthrough,” says Stephanie James, director of science and director of the Grand Challenges in Global Health Initiative at the Foundation for the National Institutes of Health, which oversaw funding of the work. “These viral vaccine vectors are being seriously examined for the development of a lot of new vaccines to address disease problems that we don’t have vaccines for yet.”
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