The first modelling study to quantify the impact of Covid-19 vaccines estimated that vaccines prevented 19.8 million out of a potential 31.4 million deaths globally in the first year after they were introduced. Experts reviewed data from December 8, 2020 to December 8, 2021 and found high and upper-middle income countries accounted for the greatest number of prevented deaths (12.2 million/19.8 million).
"Covid-19 vaccines reduced the potential global death toll during the pandemic by more than half in the year following their implementation," a mathematical modelling study published in The Lancet Infectious Diseases said. According to the study another 599,300 deaths could have been averted if the World Health Organisation's target of vaccinating 40% of the population in every country by the end of 2021 had been met.
The estimates are based on excess deaths from 185 countries and territories. According to the Lancet, in the first half of 2021, the greatest number of deaths averted by vaccination was seen in lower middle-income countries, resulting from the significant epidemic wave in India as the Delta variant emerged.
"They found that Covid-19 vaccination prevented an estimated 19.8 million deaths out of a total of 31.4 million potential deaths that would have occurred without vaccination, a reduction of 63%," it said.
More than three quarters (79%, 15.5 million/ 19.8 million) of deaths averted were due to the direct protection against severe symptoms provided by vaccination, leading to lower mortality rates.
The remaining 4.3 million averted deaths were estimated to have been prevented by indirect protection from reduced transmission of the virus and reduced burden on healthcare systems.
Overall, the number of estimated deaths prevented per person was greatest in high-income countries, reflecting the earlier and wider rollout of vaccination campaigns in these areas (66 deaths prevented per 10,000 people in high-income countries vs 2.711 deaths prevented per 10,000 people in low-income countries), it said.
For the 83 countries included in the analysis that are covered by the Covax commitment to affordable vaccines, an estimated 7.4 million deaths were averted out of a potential 17.9 million (41%).
However, failure to meet the Covax target of fully vaccinating 20% of the population in some countries is estimated to have resulted in an additional 156,900 deaths.