Getting vaccines to rural areas with little infrastructure is one of the biggest challenges for public health. Only herd immunity can stop the spread of deadly disease and eventually achieve eradication. That's why scientists are developing contagious vaccines that can be spread between wild animals and humans.
Animals are the key. A third of Ebola cases in humans are traced to contact with apes killed by the virus. Scientists will first focus on vaccine strains that will benefit animals and humans, as shrinking habitats means we overlap more and more. Vaccines administered to animals will spread to other animals, literally protecting the herd, and also jump to humans.
With a traditional vaccine you’ve got to…find each individual animal and vaccinate it, which is pretty much impossible. How do you go out there and vaccinate a bunch of deer mice against Hantavirus by hand?
It's cheaper. In addition to reaching more remote populations, its estimated that even a significantly weakened contagious version of the measles, mumps and rubella (MMR) vaccine could save $50 million each year.
We know this is possible, because a strain of the polio virus has spread between humans through a vaccine. The oral vaccine, used by the World Health Organization, contains three polio strains, and one, in rare cases, has become active and even deadly. The WHO will stop using this strain in their vaccine, but understanding how it lived in the body long enough to be transmitted to others has given scientists new insights into the potential of viruses for transmitting vaccines.
A herpes-related virus is a good candidate. Rather than using live, but weakened strains to transmit vaccines, scientists see cytomegaloviruses (CMV) as good candidate to carry vaccines. These are benign viruses in the herpes family that infect between 60-80% of human population, but cause no symptoms. A CMV could be designed to give the vaccine a ride from host to host.
(Source: Popular Science)
Photo: By Shobhit Gosain GFDL via Wikimedia Commons