Death rate from COVID-19 infection among older people in community settings lower than previous estimates

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There is a high death rate among the elderly following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with symptomatic coronavirus disease 2019 (COVID-19). As a result, older people, especially those who live in nursing homes, are very vulnerable to exposure and severe symptoms of COVID-19.

New study published on the preprint server medRxiv * discusses the results obtained from various seroprevalence studies conducted in 2020. To this end, the researchers conclude that the infection mortality rate (IFR) of COVID-19 in the elderly is not as high as is commonly believed. feared before.

Study: Death rate from COVID-19 infection in populations living in the community with an emphasis on the elderly: an overview. Image Credit: sasirin pamai

Background

Several early studies on COVID-19 were based on different cohorts of older people, with varying rates of underlying disease and different age groups. In particular, nursing home residents accounted for up to 70% of COVID-19 deaths in high-income countries during the first wave of the pandemic. The rapid rate at which this population was succumbing to COVID-19 was particularly striking, as the elderly typically make up less than a hundredth of the population in these countries.

The IFR in this subset was considered to be up to 25%, thus unduly increasing the IFR of the community. In addition, statistics for this group have fluctuated greatly from country to country due to differences in data collection and reporting. Third, community-based seroprevalence studies generally do not include this group.

How did the study go?

In the present study, researchers estimated the IFR in a community using data from several studies where seroprevalence included the elderly. The main objective was to define IFR in the elderly.

Notably, the authors excluded seroprevalence studies based on healthcare workers, which could result in an above-average rate due to a higher risk of exposure than usual. Race and ethnicity records were also a prerequisite, as both affect participation in such a study and the chances of acquiring COVID-19.

What did the study show?

In middle-income countries, researchers found that a median of 53% of total COVID-19 deaths at the site occurred in the elderly. Comparatively, in high-income countries, older people accounted for up to 86% of total COVID-19 deaths at the site. When that same data point was refined to examine deaths that occurred among residents of nursing homes, a median of 44% occurred in middle-income countries.

Remarkably, older people made up 9% and 15% of the population in middle- and high-income countries, respectively. In addition, the percentage of people residing in nursing homes ranged from 0.08 to 0.20% and a median of 4.7% in middle and high income countries, respectively.

In 14 countries, including 12 high-income countries and two middle-income countries, IFRs for older people living in the community were 2.4%. The IFR among the elderly was consistently higher in rich countries than in middle-income countries, at around 3% and 0.3%, respectively.

When individuals over the age of 85 were studied, the IFR increased sharply. For example, when people over 85 made up 5% of the population, their IFR value was estimated to be around 0.62%. Comparatively, when people over 85 made up 10% and 20% of the population, the IFR was 1.18% and 4.29%, respectively.

Infection death rate, corrected for unmeasured antibody types, represented as the proportion of people aged ≥ 85 years among the elderly. Recordten IFR: logarithm (base 10) of the case fatality rate per infection. The “seniors” group is defined by the primary threshold for each location. For example, for Belgium, 3% of the population has ≥85, and 13.6% of the population has ≥70, so the proportion is 3 / 13.6. Imputation made for regional data: Denmark (3/5 regions) and Tamil Nadu, India, with a proportion of people aged ≥85 years among the elderly at the national level.

Low IFRs among younger age groups

When studying the IFR in individuals aged 0 to 19, the researchers found that in all countries, the median IFR was 0.0027%. The median IFR also remained low at 0.014% when individuals aged 20 to 29 were studied.

However, as the age groups started to increase, their IFR values ​​followed. For example, people aged 30 to 39 and 40 to 49 had IFR values ​​of 0.031% and 0.082%, respectively. Even though adults aged 50 to 69 were studied, their IFR values ​​also increased but remained below 1%.

Taken together, the results of the present study indicate that location is a major determinant of IFR in the elderly. Second, residents of nursing homes have a significantly higher COVID-19 specific IFR than seniors who live in the community. Since the use of assisted care facilities is much more pronounced in high-income countries, this difference is highlighted in this review.

Comparison with previous research

Previous data on IFR estimates by age used seroprevalence data as well as COVID-19 mortality data stratified by age. Some researchers have suggested IFRs of around 5% and 15% at age 75 and 85, respectively. However, these estimates did not include deaths in nursing homes and were based on limited data in older age groups.

These studies were also from places with a high incidence rate and used a very long time frame in which deaths were counted as due to COVID-19.

Imperial College London also had high IFRs in the elderly, mainly because they used very narrow selection criteria, including only 10 studies in nine countries, half of which included more than a thousand subjects. Their selection bias was obvious since only the most affected areas were included in the study.

The present study estimates lower IFRs, not only in the elderly, but also in those under 50. For those under 19 and 30-39, the median IFR is

For people over 40, it is estimated that one in 1,200 people die from COVID-19. These estimates are inflated 5 to 10 times in the Imperial College study for 0-29 year olds.

What are the implications?

Since current and previous studies indicate very low IFR in individuals between the ages of 30 and 50, these data are potentially important in assessing the risk-benefit ratio of interventions such as vaccinations in these younger populations.

We hope that further research will provide more information on the role of factors other than age and being a resident of a nursing home. Obesity, for example, affects more than a third of people in high-income countries, but less than 5% in low- and middle-income countries. Other factors, such as a history of smoking, diabetes and cardiovascular disease, all of which are associated with more severe COVID-19 symptoms, are also more common in high-income countries.

Finally, it should be noted that the IFR among nursing home residents fell sharply after the first wave due to the use of better evidence-based guidelines.

Overall, the IFR was much lower among older people in community settings than that estimated for the overall older population. The difference in IFRs is greatest when nursing home care is much more common as a form of care for the elderly. However, IFRs were lower in middle-aged people.

The estimates presented here can be one of the key pieces of information that underpin public health policy decisions. With better metrics, especially vaccines, we hope that IFR estimates have already fallen further. “

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.


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