Reena Jani rose early, finished her chores in the crisp January cold and walked uphill to the road skirting her remote tribal hamlet of Pendajam in eastern India.

Riding pillion on a neighbour's motorcycle for 40 minutes through hillsides dotted with paddy fields, the 34-year-old health worker headed for the Mathalput Community Health Centre.

Jani's name was on a list of 100 health workers at the centre, making her one of the first Indians to be inoculated against Covid-19 earlier this month, as the country rolls out a vaccination programme the government calls the world's biggest.

But she had heard rumours of serious side-effects...