China has approved a new inactivated polio vaccine (IPV) that will be used to clamp down on recent outbreaks of the disease despite the country eradicating the disease in 2000.
The country’s proximity to two of the three countries in which polio remains endemic (Pakistan and Afghanistan) means that despite eliminating the disease from its domestic population – thanks to a national immunisation programme with an oral polio vaccine (OPV) first introduced in the 1960s – imported cases still occur.
The injectable IPV – developed by the Chinese Academy of Medical Sciences (CAMS) and the first to be based on the Sabin strain of polio used in the OPV – will be incorporated into routine childhood vaccination programmes.
In general IPVs are considered more effective than the live OPV product, which in some cases can cause polio but nevertheless has been amazingly successful in reducing the number of cases from 350,000 a year in the late 1980s to a couple of hundred at present.
Imported Salk polio strain-based IPVs became available in China in September 2009, according to the World Health Organization (WHO), but supplies have been limited and take-up limited by the fact that it has to be paid for out-of-pocket by the recipient.
The new Sabin-IPV was developed in response to a call by the WHO, which has been concerned about the risks associated with the large quantities of wild-type poliovirus needed for IPV production.
In particular, the agency is concerned about the situation after eradication is achieved when containment of remaining wild poliovirus stocks and a discontinuation of the live oral polio vaccine will be required.
Inactivated vaccine produced from attenuated Sabin strains is more suited to the post-eradication environment as it is based on a safer, non-infectious form of the virus and uses less wild-type material than the Salk-based vaccines.
“Sabin polioviruses pose less of a threat in the event of an intentional or unintentional release from the production facility,” says the Polio Global Eradication Initiative.
The development of the Sabin-IPV vaccine is further evidence of the growing sophistication in China’s domestic vaccines sector, which has also developed an Ebola vaccine that was approved for production late last year.