A more equitable access to Covid vaccines could have prevented more than 50 per cent of Covid-19 deaths in 20 lower income countries, according to a new study.

Scientists from the Northeastern University, US, have estimated 518,000 deaths could have been averted if the 20 countries in the study had received the vaccines at the same time as the US and other high income countries and in comparable quantities, using a computational epidemic model.

The countries included in the study were Angola, Kenya, Ghana, Cote d'Ivoire, Mozambique, Uganda, Rwanda, Zambia, Egypt, Morocco, Afghanistan, Pakistan, Sri Lanka, Bangladesh, Indonesia, Bolivia, El Salvador, Honduras, Philippines and Kyrgyzstan.

The study is published in the journal Nature Communications. The estimation that "thousands and thousands" of lives were lost to vaccine inequity was a "punch in the stomach," said Alessandro Vespignani, director of Northeastern's Network Science Institute and the study's co-author.

"We need to have a different system in place so that we have more vaccines and a more equitable distribution across the world," said Vespignani. "There is a high price for this inequity." Further, the scientists also looked at what would have happened had these nations received the vaccines earlier, but in no greater amount.

"For more than half of the countries, the percentage of deaths averted exceeds 70 per cent, with peaks above 90 per cent for Afghanistan and Uganda," the paper said. In terms of numbers of deaths, it meant that an estimated 149,000 Covid-19 deaths could have been prevented in Indonesia and 1,700 in Rwanda with earlier and more vaccines, according to the researchers.

In this case, "even without increasing the number of doses, we estimate an important fraction of deaths (6 to 50 per cent) could have been averted," they said. International health agencies and foundations anticipated the problem and tried to address it but failed to do so in time, Vespignani said.

After the Covid-19 vaccines were introduced in October of 2021, high income countries ended up with one or more doses of vaccine for every person, while low income countries had one to four doses of vaccine for every 100 individuals, according to Vespignani.

"Despite international initiatives for equitable sharing agreements such as the Covid-19 Global Vaccine Access (COVAX) program, vaccine nationalism has largely superseded global equity efforts," the study said.

"Besides being 'very costly in terms of life', vaccine inequity encourages the circulation of pathogens in countries where a large percentage of people are not inoculated," Vespignani said.

The solution wasn't just to redistribute the vaccine supply from wealthy countries to poorer ones because "you will have more deaths in the higher income countries," Vespignani said. "The issue is how to step up the system in order to have much more vaccine doses the next time a pandemic breaks out.

"Timing is important as well as the number of doses. We need to have both logistic and manufacturing capacity in place the next time so that we can really have a different outcome in those countries," Vespignani said.