Most of us alive today are familiar with vaccines. In the US where I live most of us have been vaccinated for major diseases such as whooping cough, Hepatitis A, measles, mumps, rubella, tetanus, diphtheria; the list goes on. However, due to our developed infrastructure and relative ease of access to medical care many of us have never worried about obtaining life-saving vaccines for our children or ourselves. This alone has contributed to some of the most startling gains in public health ever witnessed.
In other parts of the world this is a very different story. Less infrastructure and fewer opportunities for medical care has made vaccinating large segments of the human population extremely difficult with serious consequences for those who are not vaccinated.
One major hurdle in the race to vaccinate the majority of people on this planets is the maintenance of cold-chains for vaccine delivery.