Vaccinating older people for the first time against COVID-19 saves most lives

It has been argued that vaccinating the oldest, and therefore most vulnerable in society, to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a first priority may not be the optimal strategy for saving the greatest number of years of life.

A short paper by Goldstein, Cassidy, and Wachter, recently published online in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), mathematically shows that vaccinating the oldest first actually saves both the most lives and the most most years of life.

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The group obtained data on the age of deaths related to COVID-19 from the United States, Germany, and South Korea and found that the risk of dying from COVID-19 increases exponentially with age, being around 11% per year. However, the remaining life expectancy of people continues to decrease linearly up to extreme old age. The number of years saved by vaccinating the average person of a given age was calculated from these two data points.

The number of years saved by vaccinating a person of a given age increased almost linearly with age. For example, American 40-year-olds live approximately 0.005 years longer and 90-year-olds 0.05 years longer on average. It was predicted that vaccinating 75-year-olds would save 0.025 years of life, half as many as vaccinating 90-year-olds. In terms of the number of lives saved, the difference is significantly larger: distributing vaccines to 90-year-olds saves three times as many lives as distributing to 80-year-olds and eighty times more than distributing to 50-year-olds.

Since only these basic statistical aspects were considered in the mathematical model: risk of death from COVID-19 and years remaining at a certain age, these conclusions should generally be applied. The group notes that vaccinating the youngest patients with comorbidities or serious health problems would inevitably save most years of life if they could be successfully immunized. This model assumes, on the one hand, that the vaccine provides good and lasting immunity and, on the other hand, that the effectiveness of the vaccine is constant with age. At this point, the available vaccines appear to be satisfactorily effective in all age groups, and at least short-term immunity is relatively guaranteed after two doses.

The authors support the announced priority of the World Health Organization, which had been criticized for its decision to recommend vaccination of the elders first. Delivering the COVID-19 vaccine to those at highest risk of death remains the optimal strategy in terms of both lives saved and total life years saved.

Journal reference:

  • Vaccinating Elders Against COVID-19 Saves Both Most Lives and Most Years of Life Joshua R. Goldstein, Thomas Cassidy, Kenneth W. Wachter, National Academy of Sciences Proceedings March 2021, 118 (11) e2026322118; DOI: 10.1073 / pnas.2026322118, https://www.pnas.org/content/118/11/e2026322118

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