Covid-19 Vaccines Prevented 19.8 Million Deaths Worldwide In First Year Of Rollout: Study In Lancet

According to estimates based on excess deaths from 185 regions, as many as 19.8 million out of a potential 31.4 million Covid-19 deaths were prevented worldwide in the first year of vaccine rollout.

As many as 15.5 million deaths out of 19.8 million deaths were averted due to the direct protection against severe symptoms provided by vaccination, accounting for 79 per cent of the deaths averted. | Representative Photo

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Covid-19 vaccines prevented 19.8 million deaths worldwide in the first year of rollout, reducing the potential global death toll during the pandemic by more than half during that year, a new study published in The Lancet Infectious Diseases estimates.

According to estimates based on excess deaths from 185 countries and territories, as many as 19.8 million out of a potential 31.4 million Covid-19 deaths were prevented worldwide in the first year of the vaccination programme.

A Further 5,99,300 Lives Could Have Been Saved Had A Target Been Achieved

A further 5,99,300 lives could have been saved if the World Health Organization's target of vaccinating 40 per cent of the population in each country with two or more doses by the end of 2021 had been met, the study estimates.

Study Offers Most Complete Assessment To Date Of Global Vaccination Impact

According to a statement released by The Lancet, Dr Oliver Watson, the lead author on the paper, said the findings offer the most complete assessment to date of the remarkable global impact that vaccination has had on the Covid-19 pandemic. He added that almost 7.5 million deaths were prevented in countries covered by the Covid-19 Vaccine Access Initiative (COVAX). 

Dr Watson said the initiative was set up because it was clear early on that global vaccine equity would be the only way out of the pandemic. The findings show that millions of lives have likely been saved by making vaccines available to people everywhere, regardless of their wealth.

However, more lives could have been saved, if the targets set out by the WHO had been achieved, Dr Watson said. Roughly one in five of the estimated lives lost due to Covid-19 in low-income countries could have been prevented, if the targets set out by the WHO had been achieved.

Almost Two-Thirds Of World’s Population Has Received At Least One Dose Of Covid Vaccine

According to the study, almost two-thirds of the world's population has received at least one dose of a Covid-19 vaccine, since the first Covid-19 vaccine was administered outside of a clinical trial setting on December 8, 2020. The Covid-19 Vaccine Access Initiative (COVAX) had an initial target of giving two vaccine doses to 20 per cent of the population in countries covered by the commitment by the end of 2021. It has facilitated access to affordable vaccines for lower income countries to try to reduce inequalities. The WHO expanded the target of COVAX by setting a global strategy to fully vaccinate 70 per cent of the world's population by mid-2022, with an interim target of vaccinating 40 per cent of the population in all countries by the end of 2021. 

More Than 3.5 Million Covid-19 Deaths Reported Since Administration Of First Vaccine

More than 3.5 million Covid-19 deaths have been reported since the first vaccine was administered in December 2020, despite the incredible speed of the global vaccine rollout.

New Study Is First To Access Number Of Deaths Averted Both Directly And Indirectly

The studies which attempted to estimate the impact of vaccination on the course of the pandemic have focused on specific regions, such as individual countries, states, or cities. The study published in The Lancet Infectious Diseases journal is the first to estimate the impact of Covid-19 vaccinations on a global scale and the first to assess the number of deaths averted both directly and indirectly.

Gregory Barnsley, co-first author on the paper, said quantifying the impact that vaccination has made globally is challenging because access to vaccines varies between countries, as does everyone's understanding of which Covid-19 variants have been circulating. Also, very limited genetic sequence data is available for many countries. The number of deaths that could have occurred without vaccinations cannot be directly measured. The alternative scenarios, which cannot be directly observed in real life, can be assessed using mathematical modelling, Barnsley said.

The researchers used an established model of Covid-19 transmission using country-level data for officially recorded Covid-19 deaths occurring between December 8, 2020, and December 8, 2021. This helped them estimate the impact of global vaccination programmes.

Separate Analysis Based On Number Of Excess Deaths Recorded Conducted

The researchers carried out a separate analysis based on the number of excess deaths recorded above those that would have been expected during the same time period, to account for under-reporting of deaths in countries with weaker surveillance systems. The researchers used estimates of all-cause excess mortality to account for under-reporting of deaths in the places where official data was not available. Then, they compared the analyses with an alternative hypothetical scenario in which no vaccines were delivered.

Factors The Model Accounted For

According to the study, the model accounted for variation in vaccination rates between countries, and also the differences in vaccine efficacy in each country based on the vaccine types known to have been predominantly used in those areas. The scientists did not include China in the analysis owing to its large population and very strict lockdown measures, which would have skewed the findings.

Estimated 18.1 Million Deaths Would Have Occurred During Study Period In Absence Of Vaccination

The scientists found that an estimated 18.1 million would have occurred during the study period if vaccinations had not been implemented. They made the estimates based on officially recorded Covid-19 deaths. 

According to the study, the model estimates that vaccination has prevented 14.4 million deaths. This represents a global reduction of 79 per cent.

Vaccination Prevented 19.8 Million Deaths Out Of A Total Of 31.4 Million Potential Deaths

The scientists conducted a further analysis based on total excess deaths during the same time period to account for the under-reporting of deaths. The study 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. This represents a reduction of 63 per cent.

15.5 Million Deaths Averted Were Due To Direct Protection

According to the study, more than three quarters of deaths averted were due to the direct protection against severe symptoms provided by vaccination. This led to lower mortality rates. As many as 15.5 million deaths out of 19.8 million deaths were averted due to the direct protection against severe symptoms provided by vaccination, accounting for 79 per cent of the deaths averted.

4.3 Million Deaths Averted Due To Indirect Protection

Indirect protection from reduced transmission of the virus, and reduced burden on healthcare systems could have helped prevent an estimated 4.3 million deaths, the study found. Reduction of the burden on healthcare systems helped improve access to medical care for those most in need.

Greatest Number Of Deaths Averted In First Half Of 2021 Seen In Lower-Middle Income Countries

The study found that vaccine impact changed over time and in different areas of the world as the pandemic progressed. The greatest number of deaths averted by vaccination was seen in lower middle-income countries, in the first half of 2021. This resulted from the significant epidemic wave in India as the Delta variant emerged. In the second half of 2021, the greatest impact of vaccination was concentrated in higher income countries. This is because restrictions on travel and social mixing were eased in some areas, leading to greater virus transmission.

High And Upper-Middle Income Countries Accounted For Greatest Number Of Deaths Averted

The study found that the number of estimated deaths prevented per person was greatest in high income countries. This reflects the earlier and wider rollout of vaccination campaigns in these areas. As many as 66 deaths were prevented per 10,000 people in high-income countries, while 2.711 deaths per 10,000 people were prevented in low-income countries. 

According to the study, high and upper-middle income countries accounted for the greatest number of deaths averted, highlighting the inequalities in access to vaccines around the world. As many as 12.2 million deaths out of an estimated 19.8 million deaths were averted in the high and upper-middle income countries.

As many as 83 countries that are covered by the COVAX commitment to affordable vaccines were included in the analysis. In these countries, an estimated 7.4 million deaths were averted out of a potential 17.9 million, accounting for 41 per cent of the total deaths prevented.

Estimated 1,56,900 Deaths Occurred Because Of Failure To Meet COVAX Target

However, the study estimates that the failure to meet the COVAX target of fully vaccinating 20 per cent of the population in some countries resulted in an additional 1,56,900 deaths. The preventable deaths were concentrated in 31 African nations, in which 1,32,700 deaths could have been averted if the target had been met, the study found.

Additional 5,99,300 Deaths Could Have Been Prevented If WHO Target Was Met

An additional 5,99,300 deaths, that could have been prevented, are estimated to have occurred worldwide due to the shortfall in the WHO target of fully vaccinating 40 per cent of the population of each country by the end of 2021. The study found lower-middle income countries to account for the majority of these deaths. As many as 3,47,500 deaths out of 5,99,300 deaths worldwide occurred in lower-middle income countries due to the shortfall in the WHO target of fully vaccinating 40 per cent of the population of each country by the end of 2021. This means that 59.7 per cent of the deaths worldwide could have been prevented in the lower-middle income countries.

Most Of The Preventable Deaths Occurred In Africa And East Mediterranean Regions

Most of these deaths were focused in Africa and East Mediterranean regions. As many as 3,48,900 deaths out of 5,99,300 deaths worldwide were concentrated in Africa, while 1,26,800 deaths out of 5,99,300 deaths worldwide were concentrated in the Eastern Mediterranean regions. These accounted for 58.2 per cent and 21.2 per cent of the total deaths that could have been prevented worldwide, respectively.

According to the study, the number of deaths averted by vaccination in these areas would have more than doubled, if the 40 per cent target had been met in all low-income countries. As many as 1,80,300 deaths are estimated to have been averted in all low-income countries under current vaccination rates. Had WHO's target been met in all low-income countries, an additional 200,000 deaths would have been prevented, the study found.

Important To Ensure Most Vulnerable People In All Parts Of World Are Protected From Covid-19

Professor Azra Ghani, one of the authors on the paper, said the study demonstrates the enormous benefit that vaccines had in reducing deaths from Covid-19 globally. She added that while the intense focus on the pandemic has now shifted, it is important to ensure that 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 further said that ensuring fair access to vaccines is crucial, but requires more than just donating vaccines. She added that improvements in vaccine distribution and infrastructure, as well as coordinated efforts to combat vaccine misinformation and improve vaccine demand, are needed, because only then can it be ensured that everyone has the opportunity to benefit from these life-saving technologies.

Limitations To The Study

The authors noted several limitations to the study, including the fact that the model is based on a number of necessary assumptions. These assumptions include the precise proportion of which vaccine types have been delivered, how they were delivered and their precise timing of when new virus variants arrived in each country. 

The authors also assumed that the relationship between age and the proportion of Covid-19 deaths occurring among infected individuals is the same for each country. The scientists noted that the findings from the study should be considered in the context of uncertainty in calculating the true death toll of the pandemic, owing to the difference in country-level reporting of Covid-19 mortality.