Jacob Puliyel and colleagues highlight the importance of ensuring appropriate ethical standards are adhered to in the course of scientific studies. In our study of the fi eld effi cacy of monovalent oral type 1 poliovirus vaccine (mOPV1), we analysed existing surveillance data from acute flaccid paralysis (AFP) cases collected since 1997. The vac cines assessed were licensed for adminis tration in India by the national regulatory authority, the Drugs Controller General of India. The mOPV1 formulation assessed in our study has been used since mid-2005 by the Government of India, and now in over 20 countries around the world. (Correspondence)