Abstract:
Objective: Calculations of disease burden of COVID-19, used to allocate scarce resources, have historically considered only mortality. However, survivors often develop postinfectious ‘long-COVID’ similar to chronic fatigue syndrome; physical sequelae such as heart damage, or both. This paper quantifies relative contributions of acute case fatality, delayed case fatality, and disability to total morbidity per COVID-19 case.
Study design and setting: Healthy life years lost per COVID-19 case were computed as the sum of (incidence*disability weight*duration) for death and long-COVID by sex and 10-year age category in three plausible scenarios.
Results: In all models, acute mortality was only a small share of total morbidity. For lifelong moderate symptoms, healthy years lost per COVID-19 case ranged from 0.92 (male in his 30s) to 5.71 (girl under 10) and were 3.5 and 3.6 for the oldest females and males. At higher symptom severities, young people and females bore larger shares of morbidity; if survivors’ later mortality increased, morbidity increased most in young people of both sexes.
Conclusions: Under most conditions most COVID-19 morbidity was in survivors. Future research should investigate incidence, risk factors, and clinical course of long-COVID to elucidate total disease burden, and decisionmakers should allocate scarce resources to minimize total morbidity. WHAT IS NEW; KEY FINDINGS: : Under most plausible model scenarios, most COVID-19 morbidity (death + disability) is likely to be due to disability (‘long-COVID’) or delayed death due to organ damage, rather than immediate death. Only if long-COVID resolves (atypical of postinfectious syndromes) is morbidity higher in old than young WHAT THIS ADDS TO WHAT IS KNOWN: : While COVID-19 deaths are numerous, they likely cause less morbidity overall than does disability or organ damage in survivors. Morbidity is highest in females, especially those infected young.
What should change now: Scarce resources such as vaccines should be allocated to minimize morbidity rather than focusing solely on mortality. Data on long-COVID, especially its sex bias, should be collected and publicized.
Source: Smith MP. Estimating total morbidity burden of COVID-19: relative importance of death and disability. J Clin Epidemiol. 2021 Oct 26:S0895-4356(21)00339-5. doi: 10.1016/j.jclinepi.2021.10.018. Epub ahead of print. PMID: 34715312. https://pubmed.ncbi.nlm.nih.gov/34715312/