A new polio vaccine holds the potential to eradicate the disease from our planet in as little as three years. That’s according to a study released in the British Journal Lancet in October 2010. Dr. Roland Sutter, lead author of the study, said the new vaccine is currently in use in India, Afghanistan, Pakistan and Nigeria, as well as 15 countries in West Africa.
Roland Sutter: Last year we had in India 498 cases, this year we have, so far, 39 cases. In Nigeria, last year to November we had 382 cases, and at this point we have 9 cases. So these have been quite dramatic decreases.
Dr. Sutter said the new polio vaccine is more effective because it only targets two of the virus’s three strains – polio types one and three. Polio type two is no longer a health concern, but was included in past vaccines. And the old vaccines that immunized against all three of the polio strains required more doses.
Roland Sutter: It was never formulated for developing countries and so you get much less per dose immunity. We needed to have something better.
He said one reason that the four countries where polio has never been eliminated – India, Afghanistan, Nigeria and Pakistan – require higher immunity to combat the virus is that temperatures remain warm all year round.
Roland Sutter: In the old times, particularly in the US, polio was a summer disease. In tropical countries it’s really all year round and so the immunity needs to be higher to stop it. And in many of these countries sanitation, hygiene, organized sewage systems, and drinking water, particularly for the poorest of the poorest is usually not available and so that helps to spread the virus as well.
The development of this vaccine was a joint effort of the WHO, Unicef, CDC, and Rotary International.
Roland Sutter: This partnership has tried since 1988 to eradicate polio and was looking, really in the last couple of years, for a vaccine that’s more immunogenic, that works better in developing countries than the existing vaccines we had. This vaccine, we think, fits the bill, not only because of what we saw in the clinical trial, but what we have seen in the field so far.
One issue with vaccines that target all three strains is that there’s an order to which strains our body builds immunity to first – and this process requires more doses.
Roland Sutter: The problem with the [vaccine that immunizes against all three strains of polio] is that it contains the type two vaccine, or the type two strain. And that is by far the strongest of the three types, so it takes over. So if you want to have an immediate effect, an immediate action against, let’s say, type one, then we should not have a vaccine with type two. The body of children who get a type two-containing vaccine will respond by building immunity to type two first. Once we have immunity to type two then we can focus on type three – or type one.