Vulnerable Populations: Differential Impact of COVID-19 on Populations with Severe Mental Illness


Vol 8 #6



Mariam Abdurrahman MD, MSc,1, Ana Hategan MD2

Author information:

1   Part-time Lecturer, Staff Psychiatrist, Department of Psychiatry, University of Toronto, St. Joseph’s Health Centre (a division of Unity Health Toronto), Toronto Ontario, Canada. ✉ [email protected]

2   Clinical Professor, Geriatric Psychiatrist, Division of Geriatric Psychiatry, Department of Psychiatry and Behavioural Neurosciences, Michael G. DeGroote School of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada.



The coronavirus disease 2019 (COVID-19) pandemic has proliferated rapidly to over 10 million cases globally.1 Morbidity and mortality have been alarmingly high amongst older adults and residents of long-term care facilities, with attention largely focused on these groups.2 However, people with severe and persistent mental illness (SPMI) constitute an unrecognized but highly vulnerable group3, and the differential impact on them is yet to be recognized in the broader public discourse and systemic response to the pandemic. The authors contend that this is a critical vulnerable group that cannot continue to be overlooked for a number of reasons including the baseline excess burden of morbidity and mortality, compromised health behaviours observed with severe chronic mental illness, and limited socioeconomic capital.

Excess Burden of Morbidity and Mortality

Relative to the general population, people with SPMI have increased morbidity and mortality rates.4-7  Specifically, the prevalence of multisystem illness including cardiovascular disease, type 2 diabetes mellitus, chronic respiratory conditions and obesity is higher amongst persons with SPMI, with these conditions resulting in increased morbidity and mortality from COVID-19.4,7

Patients being treated with antipsychotics may experience leukopenia, added to which those that develop tardive dyskinesia may experience respiratory muscle dysfunction, both of which may complicate the course of respiratory infections.8  Severe mental illness is a risk factor for lobar pneumonia and secondary septicaemia and meningitis even after adjusting for smoking.9 Smoking and toxic stress are well recognized contributors to metabolic liability, associated excess morbidity and increased mortality. Alarmingly, smoking and toxic stress are both disproportionately widespread amongst this vulnerable group.

Some of the excess morbidity also stems from barriers to accessing care, dichotomized physical and mental health care, underdiagnoses, delayed diagnosis, and compromised ability to engage in recommended treatment.10,11  People with SPMI, particularly those with psychotic disorders may present with seemingly obscure, nonsensical or atypical features that interfere with clinical assessment and thereby cloud case detection. Atypical presentation by persons with psychotic disorders like schizophrenia may result in missed case detection in a group of patients who are often underdiagnosed and receive care of poor quality when they do access care.10,11  The picture is further compounded by the dual stigma of mental illness which may well prove to be toxic in patients afflicted with SPMI and COVID-19.

Compromised Health Behaviours

People with SPMI experience higher rates of chronic disease, congruent with the greater prevalence of primary behavioural risk factors for chronic disease: inadequate nutrition, inadequate physical activity, tobacco smoking, and harmful alcohol consumption.12,13 Prevalence rates of smoking are reported to be 2 to 4 times the general population rates, although the prevalence exceeds 70% in those with psychotic disorders, and substance use disorders.12-14 Smokers contract more respiratory ailments than non-smokers, with increased likelihood of progression to pneumonia.15

There is ongoing debate about the role of smoking-mediated angiotensin converting enzyme 2 (ACE2) upregulation, with the ACE2 receptor being the putative host attachment site for SARS-CoV-2, the causal virus of COVID-19.15-17  The synergistic effect of impaired mucociliary clearance, chronic inflammatory changes and ACE2 upregulation observed with smoking suggests that this is an important area for further investigation as key smoking-related comorbidities (cardiovascular disease, hypertension, and chronic obstructive pulmonary disease) are also key comorbidities for severe COVID-19 infection. If borne out, the findings related to ACE2 and smoking may hold a silver lining in the fight against tobacco as the levels of ACE2 in non-smokers and former smokers have been observed to be low.17 Although the findings are currently too premature to merit a scale up of public health tobacco cessation efforts, it creates momentum for further investigation in view of the alarming global burden of disease attributable to smoking.

Socioeconomic Capital

Epidemics rarely affect populations equally, added to which inequalities can serve as socioeconomic vectors in the spread of disease.3 Many living with SPMI reside in adverse socioeconomic environments that promote the risk of complex multisystem illness, which in turn confers increased morbidity and mortality from acute events such as COVID-19 infection. Severe mental illness also adversely influences engagement in and adherence with treatment for concurrent non-psychiatric illness.4  For patients with established healthcare networks, the disruption in these familiar networks and routines can have profound consequences in the wake of pandemic-related service reductions and adoption of virtual care.

The widespread call for virtual care modalities as a key measure in limiting patient exposure may exacerbate socioeconomic differences for the most marginalized patients. Specifically, virtual care makes the assumption that patients have secure and affordable access to cellphones or dedicated landlines, privacy, computers, and/or other access to the Internet, added to which it assumes that patients have adequate technological literacy to navigate virtual platforms. This assumption may well serve to exacerbate the gap between the haves and the have nots of access to virtual care.

As noted previously, the rate of serious medical conditions is disproportionately elevated in persons with SPMI. Preventive care is essential in managing these conditions and minimizing hospital admission. The disruption in routine care for these conditions may cause acute exacerbations, with increased morbidity and mortality in the event of contracting COVID-19. Furthermore, the disruption in routine care may subsequently result in difficulties in reengaging patients in preventive care and treatment adherence. Of greatest concern is the maladaptive impact of social distancing on a population with comparatively poor health status. With limited coping strategies, social distancing measures may result in unintended consequences such as increased smoking to cope with increased isolation. Similarly, the rates of substance use may increase, with devastating consequences such as increased overdoses and blood borne infections associated with lack of access to managed injection sites.

The relationship between SPMI and homelessness is perhaps the greatest public health liability in the unfolding pandemic. Many homeless individuals have comorbid mental illness. Not only does the proximity of shelter beds prevent physical distancing, the cognitive effects of chronic mental illness may limit the ability to adequately attend to the urgency of public health messaging and adapt to the measures recommended to reduce viral exposure.

Homelessness and SPMI each confer added morbidity and mortality risks independently. Furthermore, the morbidity and mortality effects of homelessness are magnified with age. Homeless adults are physiologically “old” at age 50.18,19  Homeless adults in their 50s have more geriatric syndromes than those two decades older who are stably housed.20 Currently, attention is focused on the disproportionate burden of COVID-19 in older adults and residents of long-term care facilities. However, the accelerated ageing of the homeless concomitant with the inability to shelter in place, and the prevalence of comorbid SPMI is a strong imperative for public health action.

A significant proportion of homeless persons and persons living with SPMI experience chronic toxic stress or prolonged activation of the stress-response system, with activation as early as childhood as a result of adverse childhood experiences.21 Coping strategies may be limited, and exposure may be recurrent, traumatic and manifold, resulting in a sustained elevated allostatic load. The compelling role of stress is evident in stress-mediated alterations in immunity, which is concerning in terms of the ability to mount an effective response to COVID-19. 22

Public Health Implications

The implications of the epidemiology of mental illness are manifold for public health. While SPMI constitutes a modest prevalence relative to other chronic conditions, SPMI consumes a significant proportion of healthcare and social service budgets, and contributes a significant burden of disease. For example, schizophrenia is a low prevalence disorder estimated at a global point prevalence of 0.28% in 2016, however, the burden of disease is substantial at 13.4 million years of life lived with disability.23 In fact, mental disorders account for the leading causes of years lived with disability globally.23 As such, it is imperative to recognize the potential for a magnified pandemic impact in this population. In the absence of this, the pandemic is poised to further widen the gap in health status, socioeconomic deprivation, and excess mortality risks associated with severe and persistent mental illness.

Recognition of and action on the differential pandemic impact on those with SPMI should involve concerted individual and population-level action. From a clinical standpoint, the index of suspicion should be high as patients with SPMI may present atypically and may do so at a delayed juncture of illness. Regardless of the chief reason for a hospital visit, patients with SPMI should be considered for COVID-19 testing. At the very least, testing should be conducted in the subgroup that are homeless in order to reduce community spread. In this instance, public health has an added role in the provision of mobile COVID-19 testing facilities, shelter-based testing, and isolation facilities while awaiting test results.

People with severe and persistent mental illness are at disproportionately increased risk of COVID-19 disease. It is imperative for pandemic response measures to explicitly address this excess risk, particularly given the substantial burden of disease borne by people with chronic mental illness. The collective goal of arresting the COVID-19 pandemic is more likely to succeed when the differential impact on vulnerable groups is addressed congruent with broader pandemic efforts.


Conflict of Interest Statement:

The authors declare no conflicts of interest concerning the subject matter of this article.



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