Recovered COVID-19 patients report a wide range of enduring symptoms, including difficulty breathing, cardiac problems, increased susceptibility to illness, and chronic fatigue [1]. CT scans have also exposed symptoms that are less immediately noticeable, such as scarring of lower lobe lung tissue [1]. Consequently, doctors believe that even after the pandemic, the long-term effects of COVID-19 will affect the lives of many people for years to come [1].
As COVID-19 initially presents as a respiratory infection, doctors have studied the enduring effects of the disease on pulmonary function. In a University of Southern California study, researchers took continuous CT scans of patients a few months after their recovery; results showed that 33% of the group had residual scars on their lungs from the disease [1]. One limitation to this study was that it focused on hospitalized patients, who more commonly experience long-term scarring. The director of the USC study expects fewer than 10% of all COVID-19 patients will experience similar scarring [1].
Other long-term effects of COVID-19 on pulmonary function can be understood by analyzing past outbreaks. Based on data from SARS and influenza epidemics, a significant number of affected populations could experience poorer blood-gas diffusion and ventilation for years after overcoming the infection [2]. Right now, the most common lung injuries noted in patients who had COVID-19 are diffuse alveolar damage and organizing pneumonia [2]. Fortunately, both of these conditions follow predictable courses in COVID-19 patients [2]. COVID-19 infection and nanomaterial exposure have demonstrable similarities in presentation as well, suggesting that pulmonary fibrosis could be another long-term effect of COVID-19 [3].
The finding that SARS-CoV-2 targets the ACE-2 receptor, present in cells throughout the body, suggests that the disease’s effects are not confined to the lungs [1]. For instance, heart damage is common in hospitalized patients [4]. Heart arrhythmia can occur during the disease and persist as an irregular heartbeat [4]. ACE-2 has cardio-protective effects, suggesting that if the virus’ presence in the body persistently diminishes ACE-2 levels, patients could be increasingly susceptible to cardiovascular disease in the long run [5]. Microemboli, which can lead to heart failure and microvascular dysfunction, have also been observed in COVID-19 patients [6].
The immune system is at risk of being negatively impacted by COVID-19, with effects drawn out long into the post-recovery period. Researchers have observed reduced immune system activity in patients who suffered from other similar viral diseases, such as SARS and measles, suggesting that this may be the case for recovered COVID-19 patients [1]. Conversely, immune overactivity has also been noted; increased activity carries the risk of causing widespread inflammation, which could negatively impact susceptible organs such as the heart [1]. Overactivity historically followed the Zika virus and other bacterial infections, before developing into Guillain-Barre syndrome [4]. No consensus has yet been reached concerning the direction of the relationship between COVID-19 and the immune system.
A final long-term implication of COVID-19 is decreased cognitive functioning. Among hospitalized patients, neurological issues have been a common motivation for hospital admission [4]. Described as persistent fatigue similar to chronic fatigue syndrome, this condition was observed two months after infection in 53% of patients in one study from Rome, [4]. Other reported consequences of COVID-19 include direct viral encephalitis, peripheral organ dysfunction, cerebrovascular changes, and systemic inflammation, all of which can contribute to a patient’s eventual development of a neurological disorder [7].
The potential long-term effects of COVID-19 on recovered patients are widespread and varied. It will take time and careful research to fully understand the scope of this unprecedented pandemic.
References
[1] M. Marshall, “The Lasting Misery of Coronavirus Long-Haulers,” September 14, 2020. [Online]. Available: https://www.nature.com/articles/d41586-020-02598-6. [Accessed: September 20, 2020].
[2] S. Salehi, S. Reddy, and A. Gholamrezanezhad, “Long-term Pulmonary Consequences of Coronavirus Disease 2019 (COVID-19): What We Know and What to Expect,” Journal of Thoracic Imaging, vol. 35, no. 4, p. W87-W89, July 2020. [Online]. Available: https://doi.org/10.1097/RTI.0000000000000534. [Accessed September 20, 2020].
[3] P. A. S. Kinaret, G. D. Giudice, and D. Greco, “Covid-19 acute responses and possible long term consequences: What nanotoxicology can teach us,” Nanotoday, vol. 35, August 2020. [Online]. Available: https://doi.org/10.1016/j.nantod.2020.100945. [Accessed September 20, 2020].
[4] J. Couzin-Frankel, “From ‘brain fog’ to heart damage, COVID-19’s lingering problems alarm scientists,” July 31, 2020. [Online]. Available: https://bit.ly/3kBEteW. [Accessed: September 20, 2020].
[5] S. Groß et al., “SARS-CoV-2 receptor ACE2-dependent implications on the cardiovascular system: From basic science to clinical implications,” Journal of Molecular & Cellular Cardiology, vol. 144, p. 47-53, June 2020. [Online]. Available: https://doi.org/10.1016/j.yjmcc.2020.04.031. [Accessed September 20, 2020].
[6] R.D. Mitrani, N. Dabas, and J. J. Goldberger, “COVID-19 cardiac injury: Implication for long-term surveillance and outcomes in survivors,” Heart Rhythm, June 2020. [Online]. Available: https://doi.org/10.1016/j.hrthm.2020.06.026. [Accessed September 20, 2020].
[7] M.T. Heneka et al., “Immediate and long-term consequences of COVID-19 infections for the development of neurological disease,” Alzheimer’s Research & Therapy, vol. 12, no. 1, p. 1-3, June 2020. [Online]. Available: https://doi.org/10.1186/s13195-020-00640-3. [Accessed September 20, 2020].
