Vaccine alliance Gavi has highlighted the improvement since the start of the year, when on average only 31 percent of people across the 92 lower-income countries had received the two initial jabs.
Half of people in poorer countries have now received two vaccine doses against Covid-19, a global vaccine alliance has said, hailing progress in closing the vaccine equity gap.
Gavi, which co-leads the Covax global vaccine distribution scheme with the World Health Organization and others, said on Thursday 92 lower-income countries receiving donor-funded jabs had reached 50-percent coverage on average.
Gavi, the WHO and others have long condemned the stark inequities in access to vaccines developed to battle the still-raging Covid pandemic.
"Vaccine inequity is the biggest moral failure of our times and people and countries are paying the price," UN Secretary-General Antonio Guterres said earlier this year.
While those inequities remain, Gavi said massive efforts to narrow the gap were paying off.
"Lower-income countries have made remarkable strides," it said in a statement celebrating the "key Covid-19 coverage milestone".
Gavi highlighted the dramatic improvement since the start of the year, when on average only 31 percent of people across the 92 countries had received the two initial jabs.
Back then, vaccine coverage in 34 of those nations stood at below 10 percent, compared to 10 countries today, it said.
Gavi said governments had successfully prioritised the vaccination of healthcare workers, with most of the lower-income countries now protecting more than 80 percent of this highest-risk group.
Derrick Sim, acting managing director of Gavi's Covax office, hailed the "vital progress".
"The pandemic is not over," he said in Gavi's statement, pointing out that "cases and deaths continue to rise and new variants pose a threat to us all".
Since the first Covid-19 vaccines became available, Covax has shipped more than 1.4 billion doses to lower-income countries around the world.