France, April 24 -- The UN's World Health Organization and children's agency Unicef, along with the Gavi Vaccine Alliance, had ​launched "The ‌Big Catch-Up" during the World Immunisation Week in ⁠2023 as a response to the 2020 pandemic, which disrupted vaccination campaigns.

The initiative, focused on children aged 1 to 5 years and spanning 36 countries in Africa and Asia, ‌ended in March this year.

About 12.3 million children who were ⁠previously "zero-dose" and had never received a vaccine were immunised against diseases such as diphtheria and polio, the agencies said. Before the drive, around 15 million ​children had not received a measles shot.

While final data is still b...