Encouraged, they introduced the DTPvaccine, which protects children from diphtheria, tetanus and pertussis (still a top seller), followed by an anti-snake-venom serum for snakebites.
But selling only in India and mainly to the government wasn't a very profitable business. (A DTPvaccine might sell for three cents a dose in India, as mandated by the government, but triple the price in the export market.) So Poonawalla shifted course.