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Optimizing oral polio vaccine efficacy

This area of research focuses on optimizing oral polio vaccine efficacy to accelerate polio eradication. It includes evaluating new vaccines and exploring novel uses of existing vaccines to enhance immunity.

Enhancing mucosal immunity in India

New data have highlighted the importance of understanding mucosal immunity in addition to humoral immunity. Research is looking at ways to both enhance mucosal immunity and also to lower the immunity threshold. Studies focus on:

  • investigate the epidemiology and determine the risk factors of decreased mucosal immunity
  • evaluate possible interventions to boost mucosal immunity
  • assess potential surrogate measures of mucosal immunity against poliovirus.

Known risk factors that contribute to compromised vaccine efficacy include chronic diarrhoea, high enteric disease burden and inadequate sanitation infrastructure. Studies are looking at ways of reducing these risk factors such as through improving nutrition, parasite treatment and combining oral polio vaccine with inactivated polio vaccine, as well as water and sanitation measures.

Mucosal immunity and polio vaccines meeting of experts: December 2010, India
Mucosal immunity study, Moradabad, India, 2011

Water and sanitation measures

This research will evaluate the impact of simple sanitation measures on vaccine efficacy – for example, increasing access to clean water by protecting hand pumps from faecal contamination.

Monovalent oral polio vaccine (mOPV)

Results of clinical trials have confirmed that the efficacy of monovalent OPVs is superior to trivalent OPV in inducing immunity against wild poliovirus type 1 and poliovirus type 3.

Bivalent oral polio vaccine (bOPV)

Bivalent oral polio vaccine simultaneously targets the two remaining types of wild poliovirus (type 1 and type 3) and was developed to improve the efficiency and impact of vaccination campaigns in areas where both poliovirus types co-circulate. Results of a multi-centre clinical trial in India have demonstrated that bivalent oral polio vaccine (bOPV) is ‘non-inferior’ to mOPV1 and mOPV3 individually, and ‘superior’ to trivalent oral polio vaccine.

Sutter R. et al. Immunogenicity of bivalent type 1 and 3 oral vaccine: a randomised, double-blind, controlled trial. Lancet 2010; 376:1682-88