Age is a major risk factor in determining the severity and progression of COVID-19. It may even be the most significant factor for disease severity based on data collected from multiple countries. In China, data showed that the case fatality ratio (CFR) of COVID-19 increases as one gets older. The CFR for people in their 40s or younger was 0.4% and for those in their 80s and older the value increased to 14.8%. Italy had the same values for CFR for those in their 40s or younger and a value of 20.2% for people in their 80s and up. In the U.S. the first death from COVID-19 reported was of an 82 year old individual and a similar trend in increasing morbidity has been seen with older age. In addition, of 5700 hospital admissions for COVID-19 in New York City, deaths were 3.3% lower in patients in their 40s and younger while 25.9% of deaths were of people in their 80s and older. In the U.S. there were also significantly higher rates of ICU admissions and hospitalization for people over the age of 65 in comparison to younger groups. Furthermore, 40% of COVID deaths in the U.S. were among the population of elderly residents of nursing homes. 

Aging

While immune memory may provide older individuals greater protection against certain disease states in comparison to younger people due to disease strains in circulation during their youth, it has yet to be seen if this offers any form of protection against COVID-19. However, what is very clear is the vulnerability of older individuals to coronavirus infection with poorer outcomes. The hypothesis for this increased susceptibility deals with the impairment of immune system function of defense against foreign bodies with age. This gradual impairment of the immune system is known as immunosenescence and has been seen in older people in response to other infections. For instance there is enhanced viral replication of influenza due to an impairment of type 1 IFN response and in older adults the same impaired IFN response is seen with flu vaccines. On top of the naturally weaker type 1 IFN response in older individuals, the coronavirus was found to be a suppressor of the type 1 IFN response further increasing vulnerability to COVID-19. As a result of such factors, vaccines may have to be adjusted for specific populations like the elderly for the sake of efficacy. 

Immunity and aging

Aging is a prominent risk factor for the severity and susceptibility to coronavirus. With age comes a general decline in immune system function which would increase one's vulnerability to disease states like COVID-19. Ultimately, understanding the effects of age could be important to comprehending the disease progression of COVID-19 and developing new treatments.

Rutgers University

Aging as a risk factor for COVID-19

Chen, Y., Klein, S. L., Garibaldi, B. T., Li, H., Wu, C., Osevala, N. M., Li, T., Margolick, J. B., Pawelec, G., and Leng, S. X. (2020). Aging in COVID-19: Vulnerability, immunity and intervention. Ageing Research Reviews, 65, 101205. doi.org/10.1016/j.arr.2020.101205.

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