Why did some families refuse vaccination for their children?

Directions: Read the passage carefully and answer the question that follows.

India’s polio-free certification, which was awarded by the World Health Organization (WHO) in 2014 for ensuring polio did not infect anyone in three straight years, took almost two decades of very hard work. Though vaccination against polio started in 1978 under India’s Expanded Programme in Immunisation, only about 40% children under five were being reached by 1984.
Following the WHO’s Polio Eradication Initiative, India launched its Pulse Polio Programme in 1995 with the target to vaccinate every child under five. It took some years, but it met targets. For successive years, each one of the country’s 26 million newborns was vaccinated against the paralysing infection not once but repeatedly for the first five years of their lives. The biggest challenges were geography (for example, in the Kosi river belt in Bihar annual floods isolate several hundred families), work-related migration and ignorance: some families would refuse vaccination because they were convinced the drops would make their children impotent.
Ensuring these lifesaving drops reach around 800 million children each year — 172 million children are reached in each nationwide round of vaccination, and then there are sub-national rounds — is a spectacular feat by any standards.