DTP

The three diseases the DTP vaccine protects against are all highly dangerous or even deadly for children if contracted.

Of the 25 million children who did not receive a single dose of DTP during 2021, 18 million of them live in low- and middle-income countries, UNICEF's statement said.

Requejo said that even before the pandemic, coverage rates of vaccination for DTP had stagnated in part because of rapidly increasing population numbers in key countries.

DTP is often used as a benchmark for vaccine coverage globally as it’s been in wide use for decades.

The number of children either not fully vaccinated with DTP, which prevents a number of potentially fatal illnesses including whooping cough, or not vaccinated at all for it rose from 19 million in 2019 to 25 million in 2021, the data shows.