The World Health Organization has recorded over 100 million confirmed COVID-19 cases and around 2.5 million deaths, in a pandemic that has devastated communities worldwide (World Health Organization). In addition to the characteristics that make COVID-19 a deadly acute disease, increasing evidence points to a long-term syndrome that afflicts certain patients. The ‘long-hauler’ phenomenon first emerged anecdotally among patients a few months into the COVID-19 pandemic, with a subset of patients reporting a diverse set of symptoms weeks or months after the typical recovery period (Barber). With nonspecific symptoms such as fatigue, headache, shortness of breath, and ‘brain fog’, medical professionals and researchers initially faced a significant challenge in distinguishing long-haul COVID-19 from more mundane conditions (Barber, Huang, Emanuel). Recent research has focused on understanding the symptoms experienced by COVID-19 long-haulers, as well as potential predictive factors and treatment options (Huang, Emanuel).
The term ‘long-hauler’ is “broadly used to characterize individuals whose symptoms persist or develop outside the initial viral infection,” however, much is still unclear about this condition (Barber). Even some young, healthy people who had mild initial infections have reported long-term symptoms — post-intensive care syndrome is a well-characterized set of disorders, but “the catch here is that long-haul COVID patients experiencing similar impairments have not all been hospitalized or critically ill” (Barber). Facing high levels of uncertainty within the medical community, many patients have driven discussion within patient-organized groups. However, as additional data on COVID-19 emerges, scientists are able to develop more precise hypotheses for research studies — for example, early studies have examined the risk of delayed cardiac complications, which may explain some of the symptoms associated with long-haul COVID-19 (Barber).
A recently published cohort study that began in the early stages of the COVID-19 outbreak and focused on long-term symptom follow-up may shed more light on this question. Huang et al. evaluated symptoms, quality of life, physical function, pulmonary function, and immune response in patients 6 months after discharge from the hospital. 1733 patients were divided into three groups based on the severity of their acute illness. Researchers found that 76% of patients reported at least one symptom at follow-up, with the highest severity group being more than twice as likely to still be experiencing at least one symptom. Fatigue or muscle weakness, sleep difficulties, and anxiety or depression were reported by 63, 26, and 23% of patients respectively. Furthermore, the highest severity group was significantly more likely than the lowest severity group to be experiencing fatigue/muscle weakness, anxiety/depression, and pulmonary diffusion impairment 6 months after being discharged, a pattern that recalls data from the 2002-2004 SARS epidemic. Huang et al. also observed a significant decrease in seropositivity and titers of neutralizing antibodies; some patients displayed persistent renal dysfunction, were newly diagnosed with diabetes, or developed venous thromboembolic diseases.
Current research suggests that COVID-19 survivors most commonly continued to experience fatigue, sleeping difficulties, and mental health problems. Patients who were more severely ill were more likely to have worse pulmonary outcomes, however, COVID-19 long-haulers also include people who experienced relatively mild initial infections (Huang). Further research is critical for efforts to prevent debilitating long-term effects, provide early treatment to reduce severity, and identify the path forward for people who are now unable to return to normal life (Huang, Emanuel).
References
Barber, Carolyn. “The Problem of ‘Long Haul’ COVID”. Scientific American. Dec. 29, 2020. https://www.scientificamerican.com/article/the-problem-of-long-haul-covid/
Emanuel, Gabrielle. “When Does COVID-19 Become A Disability? ‘Long-Haulers’ Push For Answers And Benefits”. NPR Public Health. Feb. 22, 2021. https://www.npr.org/sections/health-shots/2021/02/22/966291447/when-does-covid-19-become-a-disability-long-haulers-push-for-answers-and-benefit
Huang, Chaolin; Huang, Lixue; Wang, Yeming; et al. “6-month consequences of COVID-19 in patients discharged from hospital: a cohort study”. Lancet. 2021. vol. 397, no. 10270, pp. 220-232. doi: 10.1016/S0140-6736(20)32656-8
World Health Organization. Coronavirus Disease (COVID-19) Dashboard. Updated February 25, 2021. https://covid19.who.int/