Nearly two-thirds of the world’s population has had at least one COVID-19 vaccine, which has prevented nearly 20 million deaths, new research finds.

The study from Imperial College London was the first to quantify the impact of vaccines on a global scale. It was based on death records and estimates from 185 countries.

“Our findings offer the most complete assessment to date of the remarkable global impact that vaccination has had on the COVID-19 pandemic,” said lead author Dr. Oliver Watson, who noted that almost 7.5 million of the deaths prevented in the first year of vaccination were in countries covered by the COVID-19 Vaccine Access initiative (COVAX).

“This initiative was set up because it was clear early on that global vaccine equity would be the only way out of the pandemic,” Watson said.

In the first year of vaccination, researchers estimated that 19.8 million of a potential 31.4 million deaths were prevented. About 12.2 million prevented deaths were in high- and upper-middle income countries.

The study estimated that an additional 599,300 deaths could have been prevented if the World Health Organization (WHO) had hit its target of vaccinating 40% of the population in every country by the end of 2021.

Watson estimated that one in five COVID deaths in low-income countries could have been avoided.

Despite the speed of vaccine rollout worldwide, more than 3.5 million COVID deaths have been reported since the first was administered in December 2020, the study noted.

The findings were published June 23 in The Lancet Infectious Diseases.

To estimate the impact of global vaccination programs, the researchers relied on a model of COVID-19 transmission using country-level data for deaths recorded between December 2020 and December 2021. A separate analysis, based on number of excess deaths, was done for countries with weaker tracking systems.

The investigators also accounted for country-to-country differences in vaccination rates and effectiveness based on the major vaccine types in those areas.

China was not included because its strict lockdown measures and large population would have skewed the findings.

In all, 79% of deaths prevented owed to vaccines’ direct protection against severe COVID-19. The remaining 4.3 million prevented deaths owed to reduced transmission of the virus and the lower burden on health care systems.

The impact of the vaccines changed over time and in different regions, the study found.

In the first half of 2021, for example, the greatest number of vaccine-prevented deaths were in lower middle-income countries during the Delta wave. This shifted to higher-income countries in the second half of 2021 when travel restrictions and social distancing requirements changed.

Of 83 countries in the analysis that are part of COVAX, an estimated 7.4 million deaths were averted, but the number could have been higher if targets had been met, the study authors suggested. Preventable deaths were concentrated in Africa and the East Mediterranean.

Azra Ghani, chair of infectious disease epidemiology at Imperial College London, said the study demonstrates the enormous global benefit of vaccines.

“Whilst the intense focus on the pandemic has now shifted, it is important that we ensure the most vulnerable people in all parts of the world are protected from ongoing circulation of COVID-19 and from the other major diseases that continue to disproportionately affect the poorest,” Ghani said in a journal news release.

Ensuring fair access to vaccines requires more than just donating vaccine, she said.

“Improvements in vaccine distribution and infrastructure, as well as coordinated efforts to combat vaccine misinformation and improve vaccine demand, are needed,” Ghani said. “Only then can we ensure that everyone has the opportunity to benefit from these life-saving technologies.”

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccines.

SOURCE: The Lancet Infectious Diseases, news release, June 23, 2022

Source: HealthDay