About 20 million lives were saved by the COVID vaccine in its first year, according to new estimates.
Experts believe more deaths were prevented in richer countries, with 12.2 million saved in high and upper-middle income nations.
The Imperial College London research, published in the Lancet Infectious Diseases journal, suggests 19.8 million deaths were prevented overall.
UK grandmother Maggie Keenan was the first to get the jab outside a clinical trial on 8 December 2020, and at least 66% of the world’s population are estimated to have had at least one vaccination.
More than 11 billion jabs have been administered so far, while Johns Hopkins University in the US puts global COVID-related deaths at 6.3 million.
The Imperial research suggests another 600,000 deaths could have been avoided if a World Health Organisation (WHO) target of vaccinating 40% of the global population by the end of 2021 had been met.
The headline figures in the study were formulated from estimates on vaccination rates, COVID deaths and excess death records from 185 countries.
“COVID-19 vaccination has substantially altered the course of the pandemic, saving tens of millions of lives globally,” the study’s authors said.
“However, inadequate access to vaccines in low-income countries has limited the impact in these settings, reinforcing the need for global vaccine equity and coverage.”
Lead author Dr Oliver Watson said nearly 7.5 million deaths were prevented in countries covered by the Covax scheme, which aims to provide access to vaccines and tests to poorer countries.
“Our findings show that millions of lives have likely been saved by making vaccines available to people everywhere, regardless of their wealth,” said Dr Watson.
“However, more could have been done.
“If the targets set out by the WHO had been achieved, we estimate that roughly one in five of the estimated lives lost due to COVID-19 in low-income countries could have been prevented.”
The WHO said last month that almost a billion people in lower-income nations were still unvaccinated and that there was “insufficient political commitment to roll out vaccines” in some countries.
It said “misinformation and disinformation” was still preventing some people coming forward.
Only 57 countries – almost all of them rich nations – have been able to vaccinate 70% of their population, the WHO added.