PARIS: A jab to protect children against polio that fell out of favor in the 1960s should be given a frontline role to help stamp out the disease, doctors reported in The Lancet on Friday.
The injection can provide better and long-lasting protection against the polio virus when used to supplement oral vaccine, which replaced it in most countries, they said.
Oral polio vaccine (OPV) protects individuals against contracting the disease, but they can still be infected by the virus.
It replicates in the gut and can then be passed to others through fecal-contaminated water, thus imperiling unvaccinated children.
Scientists at Imperial College London and the Christian Medical College in Vellore, in southern India’s Tamil Nadu state, investigated whether the old-fashioned vaccine still had a part to play.
Their study involved 450 children from a poor urban area of Vellore, all of whom had received the oral vaccine as part of a standard innoculation program.
Half of the children were then given a dose of the injected vaccine, which contains an inactivated virus, and the other half given nothing.
A month later, the children were given a dose of live oral vaccine, whose formula includes a tiny amount of live polio virus, the goal being to safely simulate re-infection.
A week later, their stools were tested to see if the polio virus was present—specifically the two strains of the virus, serotypes 1 and 3, which are resisting eradication.
Among children who had received the injected vaccine, there were 38 percent fewer who had traces of serotype 1, and 70 percent fewer with serotype 3, compared to those who did not get the jab.
“Because IPV [injected polio vaccine]is injected into the arm, rather than taken orally, it’s been assumed it doesn’t provide much protection in the gut and so would be less effective at preventing fecal transmission than OPV,” said Jacob John of the Christian Medical College.
“However, we found that where the children already had a level of immunity due to OPV, the injected vaccine actually boosted their gut immunity,” he said in a press release.
He added: “In the 1960s there was extensive rivalry between the scientists who developed the two vaccines, with OPV eventually becoming the most popular.”
“But it looks as if the strongest immunity can be achieved through a combination of the two,” he added.
Also called the inactivated polio vaccine or the “Salk vaccine,” after its inventor, Jonas Salk, who developed it in 1955, the jab has long been considered an astonishingly safe and effective weapon against polio.
It is still used in dozens of countries, but in more than 120 others, oral vaccine is the exclusive choice, as it is cheaper, easier and quicker to administer.