- Wealthier countries could see a significant drop in life expectancy if Covid-19 infection rates remain high
- In a simulation, scientists looked at various infection scenarios in different regions and how it would impact mortality rates
- Sub-Saharan Africa could lose between three and five years with a 70% infection prevalence rate
Death and disease have been one of the hallmarks of 2020, and Covid-19's global impact will be felt for years, maybe even decades to come.
In one of the many ways it has changed our lives, it might also have shifted the trajectory of human life expectancy around the world according to research published in PLOS ONE.
In real life, as of 22 September 2020, there have almost been one million global deaths in total as a result of Covid-19, with the US in the lead followed by Brazil, India, Mexico and the UK.
South Africa has had almost 16 000 deaths, although global totals are expected to be higher due to limited testing and reporting, unknown factors surrounding asymptomatic spread, and the fact that countries have different methods and criteria for counting Covid-19 deaths.
"Previous epidemics such as the 1918 influenza pandemic and the 2014 Ebola virus outbreak resulted in a drop in life expectancy at birth of as many as 11.8 years and 1.6–5.6 years in the USA and Liberia, respectively," explain the researchers.
"In severely affected countries, an unprecedented surge in mortality from Covid-19 may result in significant years of life lost." This is especially true when you think of the number of other life-threatening diseases that have taken a backseat in the pandemic, and might contribute to the decline in life expectancy.
Unfortunately, figuring out by how much the current pandemic will shorten our lives isn't easy. While it disproportionately affects older sections of the population, people of all ages are affected.
Scientists aimed to answer this question with a microsimulation model that assessed the rate of infection by the coronavirus, the number of deaths it caused and deaths from other causes during the course of the year.
They applied the model to four regions: North America and Europe, Latin America and the Caribbean, Southeastern Asia and sub-Saharan Africa. They simulated 100 000 people for each five-year age group in each region.
By tweaking the infection rate (between 1% and 70%) they could see how it might change the life expectancy in each region, based on real infection rates from the Hubei province in China, where the virus originated.
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Breakdown of the model's parameters
The model has two main parameters that change across scenarios:
- Age-specific probabilities of dying from Covid-19 among the infected population
- Age-specific prevalence rate of Covid-19 infection, distributed over the year following a normal distribution centred on the middle of the year
The model also includes additional parameters that are constant across scenarios:
- Age-specific probabilities of dying taken from aggregated lifetables (five-year age groups)
- Length of illness, which is set at two weeks, following the general findings that the risk for undetected symptomatic infection after 14 days is one in 10 000
It's important to note that these are not accurate predictions due to the aforementioned reporting issues, but instead offers potential scenarios in clusters to consider.
In developed regions with higher life expectancy, if the virus prevalence exceeds 1–2%, there is an expected decline in overall life expectancy in the country. At 70% infection prevalence, Western and Latin American countries would lose between four and 11 years of their life expectancy.
In sub-Saharan Africa, the current life expectancy is 62.1 years – compared to almost 80 years in Northern America and Europe – with a fatality rate between 0.1% and 0.4% that's five times lower than the developed regions.
At 10% infection prevalence, life expectancy is expected to drop less than a year in sub-Saharan Africa, while at 70% the drop would be between three and five years.
Southeast Asian countries' loss of life expectancy falls between Africa and the Americas.
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Hampering human development
The mortality rate is generally used as an indicator of human development, and a lower life expectancy could hamper attempts to recover from the pandemic. These differences between regions could also relate to younger populations in developing countries, compared to older populations in more well-off countries.
"While this exercise does not serve as a prediction of what will happen to life expectancy in different contexts, it shows what the potential impact on life expectancy would be if the same age-specific infection rates and fatality rates of Hubei province were replicated elsewhere to regions with different population structures.
"As long as Covid-19 infection prevalence remains low in a region, the pandemic will not substantially affect life expectancy. However, above a certain Covid-19 prevalence threshold, about 2% in high life expectancy regions, the secular increasing trend in life expectancy would be broken by a period drop in life expectancy."
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