COVID-19 hospitalisation rates rise exponentially with age, inversely proportional to thymic T-cell production

Abstract

Here we report that COVID-19 hospitalisation rates follow an exponential relationship with age, increasing by 4.5% per year of life (95% CI: 4.2-5.2%). This mirrors the exponential decline of thymus volume and T-cell production (decreasing by 4.5% per year). COVID-19 can therefore be added to the list of other diseases with this property, including those caused by MRSA, West Nile virus, Streptococcus Pneumonia and certain cancers, such as chronic myeloid leukemia and brain cancers. In addition, incidence of severe disease and mortality due to COVID-19 are both higher in men, consistent with the degree to which thymic involution (and the decrease in T-cell production with age) is more severe in men compared to women. For under 20s, COVID-19 incidence is remarkably low. A Bayesian analysis of daily hospitalisations, accounting for contact-based and environmental transmission, indicates that non-adults are the only age group to deviate significantly from the exponential relationship. Our model fitting suggests under 20s have 53-77% additional immune protection beyond that predicted by strong thymus function alone. We found no evidence for differences between age groups in susceptibility to overall infection, or, relative infectiousness to others. The simple inverse relationship between risk and thymus size we report here suggests that therapies based on T-cell mechanisms may be a promising target.

ThymUS in times of stress

“…Both disease risk and thymic output are described by exponential functions that double and halve every 16 years, respectively 18 . Interestingly, this correlation also holds true for COVID-19 susceptibility 19 .…”

COVID-19: THREE PHASES OF THE PANDEMIC. Dynamics of cases, deaths and tests related to SARS-CoV-2 A systematic analysis of 213 countries and territories

“…115,123 There are plenty of studies which revealed that in certain cases, various prophylactic measures used to prevent the spread of SARS-CoV-2 and other viruses and bacteria, could have negative effects on the human body, have low efficacy or may even be useless in terms of prevention of diseases. Since the main target for SARS-CoV-2 are people with the weak immunity, 13,[40][41][42] and prolonged mental stress affects both the entire body, [124][125][126]236 and the immune system in particular, [237][238][239][240][241] a new study is needed to answer the question, if medical and non-medical measures used to prevent the spread of SARS-CoV-2 could affect natural immunity. This question is especially relevant for countries which had a dramatic increase in cases and deaths during the third phase of the pandemic.…”

COVID-19: Three Phases of the Pandemic. Dynamics Of Cases, Deaths And Tests Related To SARS-CoV-2 A Systematic Analysis of 213 Countries and Territories

“…115,123 There are plenty of studies which revealed that in certain cases, various prophylactic measures used to prevent the spread of SARS-CoV-2 and other viruses and bacteria, could have negative effects on the human body, have low efficacy or may even be useless in terms of prevention of diseases. Since the main target for SARS-CoV-2 are people with weak immunity, 13,[40][41][42] and prolonged mental stress affects both the entire body, 124-126,254 and the immune system in particular, [255][256][257][258][259] a new study is needed to answer the question, if medical and non-medical measures used to prevent the spread of SARS-CoV-2 could affect natural immunity. This question is especially relevant for countries which had a dramatic increase in cases and deaths during the third phase of the pandemic.…”

“…40,96 The risk of COVID-19 hospitalization rises exponentially with age, inversely proportional to T-cell production. 41 In COVID patients, thymus enlargement was frequent and associated with increased T-lymphocytes production that appears to be a beneficial adaptation to virus-induced lymphopenia. The loss of thymic reactivation might contribute to a worse prognosis.…”

“…The same problem has arisen with the treatment of COVID-19. The main pathologic target was T-cell immunedeficiency, 13,[40][41] nevertheless a lot of attention was paid to the cytokine storm which was a consequence, but not a primary cause. According to basic medical law, treatment should be focused more at restoring T-cell immunity, 42 and less against increased activity of certain components of the immune system.…”