When the Cure is Worse than the Disease for the Unlucky Few: Polio Vaccine
NPR: Mutant Strains Of Polio Vaccine Now Cause More Paralysis Than Wild Polio
For the first time, the number of children paralyzed by mutant strains of the polio vaccine are greater than the number of children paralyzed by polio itself.
So far in 2017, there have been only six cases of "wild" polio reported anywhere in the world. By "wild," public health officials mean the disease caused by polio virus found naturally in the environment.
By contrast, there have been 21 cases of vaccine-derived polio this year. These cases look remarkably similar to regular polio. But laboratory tests show they're caused by remnants of the oral polio vaccine that have gotten loose in the environment, mutated and regained their ability to paralyze unvaccinated children.
... The oral polio vaccine used throughout most of the developing world contains a form of the virus that has been weakened in the laboratory. But it's still a live virus. (This is a different vaccine than the injectable one used in the U.S. and most developed countries. The injectable vaccine is far more expensive and does not contain live forms of the virus.)
..."As the virus starts circulating in the community, it acquires further mutations that make it basically indistinguishable from the wild-type virus. It's polio in terms of virulence and in terms of how the virus spreads."
... But for now, the live vaccine continues to be the workhorse of the global polio eradication campaign for a couple of reasons. First it's cheap, costing only about 10 cents a dose versus $3 a dose for the injectable, killed vaccine.
... The killed vaccine doesn't fully block the virus from spreading because a person who is immunized can still carry and spread the polio virus. And this is an important difference between these two types of vaccines when the goal is to exterminate the polio virus... In 1988, when the campaign began, there were 350,000 cases of polio around the world each year compared with the six so far this year.
DIGLLOYD: OMG. But it is a risk assessmsent situation; see the last paragraph above and read the whole article. Still, I don’t know how 6 is 21.
What if this mutant polio virus acquires new super powers by futher mutation?
What does this imply for a vaccine hastily developed for SARS-CoV2? Maybe nothing, but it shows that assumptions, even well established ones, should always be questioned regularly.
