The polio virus may be able to mutate to avoid vaccines, researchers have revealed.
A mutant form of the virus has been discovered in a study of an outbreak that took place in the Congo in 2010.
The findings are alarming because polio has resurfaced as a threat in troublespots around the world – in spite of a global drive to eradicate it.
The German researchers confirmed that the strain they found was vaccine resistant by tests on blood samples from 34 medical students, all vaccinated in childhood.
The research was undertaken at the University of Bonn.
The researchers say the mutant strain may not yet be able to cause an outbreak on its own. The original outbreak in the Congo was halted, partly through a vaccination programme.
Researcher Dr Jan Felix Drexler said: "We isolated polio-viruses from the deceased and examined the viruses more closely. The pathogen carries a mutation that changes its form at a decisive point."
The researchers add: "We can’t afford to sit back and do nothing. We need to further increase the vaccination rate and develop new, more potent vaccines. Only in this way do we have a chance of permanently vanquishing polio."
* A second study in the journal Science last night suggests using two vaccines as part of the anti-polio campaign.
The Indian researchers say that the inactivated polio vaccine is an effective booster for children given the live polio vaccine and more effective than a second shot of the live vaccine.
Robustness against serum neutralization of a polio virus type 1 from a lethal epidemic of poliomyelitis in the Republic of Congo, 2010; PNAS 18 August 2014; doi: 10.1073/pnas.1323502111
Efficacy of inactivated poliovirus vaccine in India. Science 21 August 2014 [abstract]
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