Global immunization efforts have saved at least 154 million lives in the past 50 years, the World Health Organization said Wednesday, adding that most of those to benefit were infants.

That is the equivalent of six lives saved every minute of every year of the half century, the UN health agency said.

Thanks to these vaccines, "a child born today is 40 percent more likely to see their fifth birthday than a child born 50 years ago", WHO chief Tedros Adhanom Ghebreyesus told reporters.