COVID-19–Related Medical Vulnerability and Mental Health Outcomes Among US First Responders

First responders’ occupations carry inherent risks, which have increased exponentially due to the COVID-19 pandemic. Findings suggest that first responders with COVID-19–related health risks are more likely to experience anxiety and depressive symptoms. As such, incorporating comprehensive assessments of health history and job-related duties can help inform prevention approaches.

Objective

The present investigation examined the main and interactive effects of coronavirus disease 2019 (COVID-19)–related medical vulnerability (CMV; the number of medical conditions with potential to elevate COVID-19 risk) and first responder status (emergency medical services roles vs non–emergency medical services roles) on mental health symptoms.

Methods

A national sample of 189 first responders completed an online survey between June and August 2020. Hierarchal linear regression analyses were conducted and included the following covariates: years served as a first responder, COVID-19 exposure, and trauma load.

Results

Unique main and interactive effects emerged for both CMV and first responder status. COVID-19–related medical vulnerability was uniquely associated with anxiety and depression, but not alcohol use. Simple slope analyses revealed divergent results.

Conclusions

Findings suggest that first responders with CMV are more likely to experience anxiety and depressive symptoms and that these associations may vary by first responder role.

LEARNING OUTCOMES

• Describe the occupational hazards associated with first responder professions.

• Outline the impact of the coronavirus disease 2019 (COVID-19) pandemic on first responder duties, length and frequency of shifts, and mental health, particularly for those who provide emergency medical services.

• Explain how COVID-related medical vulnerability and the unique roles of a first responder may affect mental health, including symptoms of anxiety and depression, as well as alcohol use severity.

The coronavirus disease 2019 (COVID-19) pandemic has led to more than 92 million cases and more than 1 million confirmed deaths in the United States.¹ Since the beginning of the pandemic, first responders, including firefighters, emergency medical services (EMS) personnel, and law enforcement officers, have been working on the frontlines to mitigate this public health crisis. Because of their critical roles in the pandemic, first responders have been identified as a high-risk group for COVID-19 exposure.² First responders' occupations are characteristically risky, and most are resilient, whereas a subset is at increased risk of physiological and psychological harm due to the potential dangers encountered while on duty.^3,4 In light of the unpredictability of the COVID-19 pandemic, including the frequency of emergency calls, number of available personnel, and the need to self-isolate from family because of direct COVID-19 exposure, the physical and mental health toll of the pandemic on first responders may be considerable.^5,6 Therefore, it is crucial to examine factors related to mental health symptoms among first responders given the ongoing pandemic.

The mental and physical health sequelae of the occupational demands of first responders have gained increasing attention in recent years.⁷ First responders frequently experience long work shifts⁸ and are more susceptible to experiencing potentially traumatic events.³ Symptoms of anxiety, depression, posttraumatic stress disorder, and alcohol use have been identified as occurring at higher rates among first responders, compared with the general population.^3,9 Furthermore, first responders are at increased risk to develop significant physical health issues, including cardiovascular disease, diabetes, obesity, and other adverse medical conditions,⁴ which can increase rates of morbidity and mortality. For instance, a retrospective review of medical examiner records found that most duty-related cardiac deaths among first responders—accounting for approximately 42% of all firefighter duty-related fatalities over the past decade—are associated with coronary heart disease.¹⁰ Relatedly, a review of health risks linked with first responder occupations found that 75% of emergency responders have prehypertension or hypertension (ie, elevated blood pressure) and are overweight or obese.¹¹ These health risks may increase the likelihood of complications related to COVID-19 in first responders, given that preexisting cardiovascular and respiratory conditions impact COVID-19–related illness severity and fatality (eg, hypertension, cardiovascular disease, respiratory disease).^12,13 Thus, COVID-19 exposure among first responders with cardiovascular, respiratory, and/or immune conditions may exacerbate mental health symptoms. Emerging research has documented increased anxiety and depressive symptoms, as well as alcohol use in at-risk groups (eg, health care workers), during the pandemic.^14,15 As such, investigating the effect of medical vulnerability to COVID-19 on the mental health of first responders may serve to better inform our understanding of the psychological impact of the pandemic on this at-risk group, thus informing relevant policy efforts going forward.

Notably, compared with hospital-based health care workers, there is limited empirical work examining associations between COVID-19–related medical vulnerability (CMV), defined as the total number of medical conditions with the potential to elevate COVID-19 risk (eg, respiratory diseases, hypertension, cardiac problems, immune diseases), and mental health symptoms among first responders. The dearth of research in this domain is critical, given the higher incidence of COVID-19 infection in first responders compared with hospital-based health care workers.¹⁶ Nascent research highlights the resilience and fortitude of first responders during the pandemic,¹⁷ potentially due to increased camaraderie and community support, which can increase during large-scale disaster situations.¹⁸ However, a growing body of work, albeit small, has underscored the potentially deleterious effects of the COVID-19 pandemic on first responder mental health. Notably, in two qualitative studies of 31 first responders, Zolnikov and Furio^6,19 found that stigma and social distancing contributed to greater anxiety and depressive symptoms, isolation, and stress. In addition, in two studies using mixed samples of first responders and health care workers, symptoms of depression, anxiety, and posttraumatic stress disorder were all elevated because of COVID-19–related occupational burdens and stressors.^20,21 Similarly, other research has found higher levels of occupational burnout and perceived stress among Polish emergency dispatchers due, in part, to the burdens associated with COVID-19.²² Indeed, long shift work and reduced personnel because of COVID-19 exposure and infection may have amplified the mental and physical health risks of first responder work.^8,23,24

A recent study found that COVID-19–related worry and medical vulnerability were associated with greater anxiety and depressive symptoms in first responders and demonstrated that those exposed to COVID-19 were more likely to serve in EMS roles (eg, performing any EMS-related duties) versus non-EMS roles.²⁵ Whereas the majority of US fire departments provide both fire suppression and EMS, approximately 38% do not²⁶; thus, it is possible that differences in physical and mental health risk may exist between first responder populations (eg, firefighters and paramedics/EMS personnel). Therefore, building upon this work, the present investigation, utilizing data collected between June to August 2020, sought to examine the main and interactive effects of CMV and first responder status (EMS roles vs non-EMS roles) on anxiety symptoms, depressive symptoms, and alcohol use. First, we hypothesized that first responders with greater CMV would endorse more severe mental health symptoms (ie, anxiety, depression, and alcohol use severity). Second, we hypothesized that, because of potentially higher rates of direct COVID-19 exposure through direct medical services, first responders in EMS roles would endorse more severe mental health outcomes compared with first responders in non-EMS roles. Finally, it was hypothesized that the effect of CMV on mental health symptoms and alcohol use would be moderated by first responder status. Specifically, first responders in EMS roles were expected to report higher levels of mental health symptoms and alcohol use, compared with those in non-EMS roles, after accounting for the following theoretically relevant covariates: years served as a first responder,²⁷ exposure to COVID-19,²⁰ and trauma load (ie, total number of traumatic event types endorsed).³

METHOD

Participants

The sample for the current study included 189 first responders (mean age, 47.58 [SD, 10.93]; 21% female), recruited via a national first responder service agency e-mail distribution list between June and August 2020. Approximately 68% (n = 129) of the sample was identified as first responders who perform EMS duties (ie, EMS roles, including paramedics and emergency medical technicians [n = 35; 18.5%], firefighters with EMS duties [n = 91; 48.1%], and law enforcement officers with EMS duties [n = 3; 1.6%]), whereas 32% (n = 60) of the sample was identified as first responders who do not perform EMS duties (ie, non-EMS roles, including firefighters [n = 59; 31.2%] and law enforcement officers [n = 1; 0.05%]). Table 1 shows a summary of participant characteristics. Inclusion criteria for the study included the following: individuals had to be currently working as a first responder in a career and/or volunteer capacity and had to be 18 years of age or older. Exclusion criteria for the study included an inability or unwillingness to provide consent.

TABLE 1.

Participant Sociodemographic Characteristics

Variable	Mean (SD)/n (%)
	Total (N = 189)	EMS (n = 129)	Non-EMS (n = 60)
Age, y	47.58 (10.93)	46.45 (9.66)	50.0 (13.01)
Sex
Male	149 (78.8%)	95 (73.6%)	54 (90.0%)
Female	40 (21.2%)	34 (26.4%)	6 (10.0%)
Race
White	167 (88.8%)	119 (92.2%)	48 (80.0%)
Black or African American	5 (2.7%)	4 (3.1%)	1 (1.7%)
American Indian or Alaskan Native	8 (4.3%)	3 (2.3%)	5 (8.3%)
Asian	3 (1.6%)	1 (0.8%)	2 (3.3%)
Native Hawaiian or other Pacific Islander	1 (0.5%)	0 (0.0%)	1 (1.7%)
Other	4 (2.1%)	2 (1.6%)	2 (3.3%)
Ethnicity (Hispanic or Latino)	8 (4.3%)	5 (3.9%)	3 (5.0%)
Marital status
Single	17 (9.0%)	10 (7.8%)	7 (11.7%)
Married	142 (75.1%)	96 (74.4%)	46 (76.7%)
Divorced	15 (7.9%)	13 (10.1%)	2 (3.3%)
Widowed	1 (0.5%)	1 (0.8%)	0 (0.0%)
Living with partner	14 (7.4%)	9 (7.0%)	5 (8.3%)
Veteran status (yes)	22 (11.6%)	15 (11.6%)	7 (11.7%)
Employment status
Part-time paid	13 (6.9%)	10 (7.8%)	3 (5.0%)
Part-time volunteer	16 (8.5%)	6 (4.7%)	10 (16.7%)
Full-time paid	141 (74.6%)	103 (79.8%)	38 (63.3%)
Full-time volunteer	19 (10.1%)	10 (7.8%)	9 (15.0%)
Occupation
Firefighter	59 (31.2%)	—	59 (98.3%)
Firefighter with EMS duties	91 (48.1%)	91 (70.5%)	—
EMS/EMT/paramedic	35 (18.5%)	35 (27.1%)	—
Law enforcement officer	1 (0.05%)	—	1 (1.7%)
Law enforcement officer with EMS duties	3 (1.6%)	3 (2.3%)	—
Years in service	20.61 (11.06)	19.81 (9.94)	22.34 (13.08)
Geographic location (by US region)
Northeast	33 (17.6%)	19 (14.7%)	14 (23.3%)
Midwest	66 (35.1%)	52 (40.3%)	14 (23.3%)
South	66 (35.1%)	42 (32.6%)	24 (40.0%)
West	23 (12.2%)	15 (11.6%)	8 (13.3%)
Geographic location (by population density)
Urban	71 (37.8%)	56 (43.4%)	15 (25.0%)
Suburban	83 (44.1%)	53 (41.1%)	30 (50.0%)
Rural	34 (18.1%)	20 (15.5%)	14 (23.3%)
Trauma loada	12.30 (2.68)	12.41 (2.43)	12.05 (3.16)
Probable clinical anxietyb	35 (18.5%)	25 (19.4%)	10 (16.7%)
Probable clinical depressionc	32 (16.9%)	22 (17.1%)	10 (16.7%)
Endorsed alcohol use	166 (87.8%)	115 (89.1%)	51 (85%)
COVID-19 exposure (yes)d	122 (64.6%)	90 (69.8%)	32 (53.3%)
COVID-19 positive testd	6 (3.2%)	2 (1.6%)	4 (6.7%)

Data derived from the Demographic and Medical Questionnaire unless otherwise noted.

^aLife Events Checklist for DSM-5.

^bCOVID-19–Adapted Overall Anxiety Severity and Impairment Scale total score greater than 8.

^cCOVID-19–Adapted Overall Depression Severity and Impairment Scale total score greater than 7.

^dCOVID-19 Exposure Questionnaire.

COVID-19, coronavirus disease 2019; EMS, first responders in emergency medical services roles; EMT, emergency medical technician.

Measures

Demographic and Medical Questionnaire

The Demographic and Medical Questionnaire is a 41-item survey that obtains participant sociodemographic information (eg, age, sex, relationship status, first responder role, years of first responder–related service) and medical history. The number of years served as a first responder was used as a covariate in the present study. COVID-19–related medical vulnerability was defined as any medical condition or history with potential to elevate COVID-19 risk. A CMV severity score was produced by totaling the following items: “Do you have any medical conditions (eg, respiratory disease) or history (eg, weakened immune system due to an autoimmune disease or HIV) that puts you in a higher risk group relevant to COVID- 19?” “Have you ever had any heart problems?” “Do you have high blood pressure (hypertension)?” and “Have you had any chest pains in the last 2 years?” COVID-19–related medical vulnerability was used as a predictor in the present study. A dichotomous first responder status variable was created to indicate if an individual performed or did not perform EMS duties (0 = non-EMS, 1 = EMS) and was utilized as a moderator in the present study.

COVID-19 Exposure Questionnaire

The COVID-19 Exposure Questionnaire²⁵ is an 8-item questionnaire that assesses an individual's level of exposure to COVID-19. Items examine both direct (eg, receiving a positive COVID-19 diagnostic test result) and indirect types of exposure (eg, living within the household of someone who has tested positive for COVID-19). A dichotomous variable was produced to indicate if an individual was exposed to COVID-19 (0 = no, 1 = yes) by totaling the items examining direct and indirect exposure to COVID-19. The COVID-19 exposure variable (yes/no) was included as a covariate in the present study.

Life Events Checklist for DSM-5

The Life Events Checklist for DSM-5²⁸ (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) is a 17-item, self-report assessment that screens for traumatic events experienced by a participant in their lifetime. A list of 16 potentially traumatic events, plus an additional question assessing “other” potentially traumatic events that are not listed in the survey, is presented to the participant. Participants indicate whether each listed event “happened to me,” “witnessed it,” “learned about it,” “part of my job,” or “not sure.” If participants endorsed that an event “happened to me,” “witnessed it,” or “part of my job,” it was coded as positive exposure to that particular type of traumatic event. Total exposures were summed to produce a “trauma load” variable indicating the total number of traumatic life event types endorsed. Trauma load was included as a covariate in the present study.

Overall Anxiety Severity and Impairment Scale

The Overall Anxiety Severity and Impairment Scale (OASIS)²⁹ is 5-item, self-report assessment examining symptoms of anxiety in the past week using a 5-point (0 to 4) Likert-type scale. The scale was adapted to include a longer time frame for the current study, which involved changing “past week” to “since the onset of COVID-19.” The OASIS has demonstrated good psychometric properties in past work and has the recommended cutoff for clinical anxiety as a score that is greater than 8.³⁰ In the current study, the internal consistency was good (α = 0.89), and the OASIS total score was utilized as an outcome variable.

Overall Depression Severity and Impairment Scale

The Overall Depression Severity and Impairment Scale (ODSIS)³¹ is 5-item, self-report assessment examining symptoms of depression in the past week using a 5-point (0 to 4) Likert-type scale. The scale was adapted to include a longer time frame for the current study, which involved changing “past week” to “since the onset of COVID-19.” Similar to the OASIS, the ODSIS has shown good psychometric properties and has the recommended cutoff for clinical depression as a score that is greater than 7.³² For the current study, the internal consistency was excellent (α = 0.94), and the ODSIS total score was utilized as an outcome variable.

Mental Health Correlates Questionnaire

The Mental Health Correlates Questionnaire²⁵ is an 11-item questionnaire that assesses how the COVID-19 pandemic has impacted mental health. Two items in the Mental Health Correlates Questionnaire that assessed current drinking were utilized to produce an “alcohol use severity” variable (frequency × quantity). The alcohol use frequency item asked: “How often do you have a drink containing alcohol?” and participants indicated their use via a 5-point scale (0 = never to 4 = four or more times a week). A follow-up question that asked participants to indicate the total number of alcoholic drinks they consumed on a typical day (0 = 1 or 2 to 4 = 10 or more) was provided to participants who reported current alcohol use. For the current study, alcohol use severity was used as an outcome variable.

Procedure

Study participants were recruited on a national level via a first responder agency e-mail distribution list. Subscribers on the list were provided study-related details, as well as hyperlinks to a consent form and study-related surveys through e-mail. The e-mail informed participants that the study intended to examine the impact of the COVID-19 pandemic on first responders' mental health symptoms. Prospective participants of the study were told that the online survey would take approximately 15 to 20 minutes to complete and were also provided the option to enroll in a raffle for the chance to win a $50 e-gift card. After consenting via the online consent form, participants were routed to the survey and were asked a series of questions regarding their current employment as a first responder and age to determine eligibility. Eligible participants then had the opportunity to answer the remainder of the survey. Participants were informed that they could discontinue participating at any time without penalty. The study protocol was approved by relevant institutional review boards.

Data Analytic Plan

All analyses were conducted in IBM SPSS Statistics version 28.0 (IBM Corp, Armonk, New York). First, data were evaluated for normality, multicollinearity, and missingness. Less than 5% of the data for study variables were reported missing, and this was handled via list-wise deletion. The data demonstrated normality and nonmulticollinearity. Second, descriptive statistics (Table 1), bivariate correlations (Table 2), and four hierarchical regression analyses (Table 3) were conducted for all study variables. At step 1, years served as a first responder, exposure to COVID-19 (yes/no), and trauma load were entered as covariates. At step 2, the predictor variables of CMV (total number of medical conditions endorsed with potential to elevate COVID-19 risk) and first responder status (EMS vs non-EMS) were entered. At step 3, the interactive effect of CMV by first responder status was entered. Main and interactive effects were evaluated for the following outcome variables: (1) anxiety symptoms, (2) depressive symptoms, and (3) alcohol use severity. Finally, simple slope post hoc analyses were conducted to probe the significant interactions at different levels of the moderator.

TABLE 2.

Bivariate Correlations of Study Variables (N = 189)

	1	2	3	4	5	6	7	8
1. Years in servicea	—
2. COVID-19 exposure (yes)b	0.04	—
3. Trauma loadc	0.11	0.13	—
4. First responder statusa	−0.11	0.16*	0.06	—
5. COVID medical vulnerabilitya	0.20**	−0.06	0.10	−0.05	—
6. Anxiety symptomsd	−0.06	0.01	0.16*	0.15*	0.27**	—
7. Depressive symptomse	−0.17*	0.06	0.11	0.09	0.28**	0.75**	—
8. Alcohol use severityf	−0.21**	0.17*	0.03	−0.07	0.04	0.04	0.16*	—
Mean	20.61	—	12.30	—	0.61	4.61	3.69	1.44
SD	11.06	—	2.68	—	0.89	4.02	4.22	2.45
Range	0–54	0.1	0–16	0.1	0–4	0–20	0–20	0–16

*P < 0.05, **P < 0.01.

^aDemographics and Medical Questionnaire.

^bCOVID-19 Exposure Questionnaire.

^cLife Events Checklist for DSM-5.

^dCOVID-19–Adapted Overall Anxiety Severity and Impairment Scale.

^eCOVID-19–Adapted Overall Depression Severity and Impairment Scale.

^fAlcohol use frequency × quantity derived from Mental Health Correlates Questionnaire.

COVID-19, coronavirus disease 2019.

TABLE 3.

Main and Interactive Effects of COVID-19–Related Medical Vulnerability and First Responder Status on Symptoms of Anxiety, Depression, and Alcohol Use Severity (N = 189)

	ΔR2	B	SE	t	P
Anxiety symptoms
Step 1	0.032				0.110
Years in service		−0.07	0.03	−1.02	0.310
COVID-19 exposure		−0.01	0.61	−0.13	0.897
Trauma load		0.17	0.11	2.34	0.020
Step 2	0.094				<0.001
First responder status		0.15	0.61	2.05	0.041
CMV		0.28	0.32	3.99	<0.001
Step 3	0.024				<0.001
First responder status × CMV		−0.25	0.64	−2.25	0.025
Depressive symptoms
Step 1	0.049				0.025
Years in service		−0.19	0.03	−2.60	0.010
COVID-19 exposure		0.05	0.64	0.65	0.519
Trauma load		0.13	0.12	1.74	0.084
Step 2	0.103				<0.001
First responder status		0.06	0.63	0.92	0.361
CMV		0.33	0.33	4.66	<0.001
Step 3	0.026				<0.001
First responder status × CMV		−0.27	0.66	−2.40	0.018
Alcohol use severity
Step 1	0.075				0.002
Years in service		−0.22	0.02	−3.10	0.002
COVID-19 exposure		0.17	0.36	2.38	0.018
Trauma load		0.03	0.07	0.39	0.694
Step 2	0.024				0.002
First responder status		−0.12	0.38	−1.72	0.087
CMV		0.10	0.20	1.31	0.191
Step 3	0.088				<0.001
First responder status × CMV		−0.49	0.38	−4.43	<0.001

Bold text indicates a significant P value.

First responder status = first responders in EMS roles (eg, performing any EMS-related duties) or non-EMS roles (0 = non-EMS; 1 = EMS). All study variables were derived from the following: Demographics and Medical Questionnaire, COVID-19 Exposure Questionnaire, Life Events Checklist for DSM-5, COVID-19–Adapted Overall Anxiety Severity and Impairment Scale, COVID-19–Adapted Overall Depression Severity and Impairment Scale, and Mental Health Correlates Questionnaire.

CMV, COVID-19–related medical vulnerability (total number of medical conditions with the potential to elevate COVID-19 risk); COVID-19, coronavirus disease 2019.

RESULTS

Descriptive statistics and zero-order correlations among study variables are presented in Table 2. Table 3 and Figure 1 present a summary of main and interactive effects of first responder status and CMV on outcomes. Regarding anxiety symptoms, covariates (ie, years served as a first responder, exposure to COVID-19, and trauma load) in step 1 were not significant correlates. Step 2 accounted for 9.4% of unique variance in anxiety with both first responder status and CMV demonstrating significant main effects. In step 3, the interactive effect of CMV by first responder status accounted for 2.4% of unique variance in anxiety. Simple slope analyses demonstrated that the association between greater CMV and elevated anxiety was significant for first responders in non-EMS roles (B = 2.18, SE = 0.51, P < 0.001, sr² = 0.24), but not for those in EMS roles (B = 0.71, SE = 0.39, P = 0.08, sr² = 0.03).

FIGURE 1.

Interactive effects of COVID-19–related medical vulnerability and first responder status on anxiety and depression symptom severity and alcohol use severity. ––– = non-EMS role; - - - - = EMS role. COVID-19, coronavirus disease 2019; EMS, emergency medical services.

Regarding depressive symptoms, the inclusion of covariates in step 1 accounted for 4.9% of significant variance, and years served as a first responder was a significant negative correlate. Step 2 accounted for 10.3% of unique variance in depression, with CMV demonstrating a significant main effect on depression, but not first responder status. In step 3, the interactive effect of CMV by first responder status accounted for 2.6% of unique variance in depression. Simple slope analyses demonstrated that the association between greater CMV and elevated depression was significant for first responders in non-EMS roles (B = 2.31, SE = 0.57, P < 0.001, sr² = 0.22), but not for those in EMS roles (B = 0.79, SE = 0.40, P = 0.051, sr² = 0.03).

Regarding alcohol use severity, the inclusion of covariates in step 1 accounted for 7.5% of significant variance to the model. Years served as a first responder and COVID-19 exposure were incrementally associated with alcohol use. Step 2 accounted for 2.4% of unique variance in alcohol use, but neither CMV nor first responder status evinced significant main effects. In step 3, the interactive effect of CMV by first responder status accounted for 8.8% of unique variance in alcohol use. Simple slope analyses revealed that the association between CMV and alcohol use was significant for both first responders in EMS roles (B = −0.49, SE = 0.22, P = 0.026, sr² = 0.04) and non-EMS roles (B = 1.11, SE = 0.39, P = 0.006, sr² = 0.12). However, first responders in non-EMS roles with greater CMV demonstrated higher alcohol use, whereas first responders in EMS roles with greater CMV demonstrated lower alcohol use.

DISCUSSION

The current study sought to examine the main and interactive effects of CMV (ie, the number of medical conditions with the potential to elevate COVID-19 risk) and first responder status (ie, first responders in EMS roles vs non-EMS roles) on anxiety symptoms, depressive symptoms, and alcohol use severity. As predicted, first responders who reported higher levels of CMV evinced greater mental health symptom severity, including anxiety and depression. These findings are in line with the extant literature demonstrating associations between symptoms of medical conditions and psychiatric symptoms in the general population^33,34 and provide empirical evidence of these relationships in first responders. Indeed, at the bivariate level, CMV was significantly and positively associated with anxiety and depressive symptoms. Interestingly, CMV was not associated with alcohol use severity. Research examining the association between physical illness and alcohol use is mixed—some work highlights the prophylactic benefits of low to moderate alcohol consumption (ie, up to one drink per day for women and up to two drinks for men) on cardiovascular health in the general population³⁵ and firefighters,³⁶ whereas other works suggest a deleterious effect on respiratory functioning and risk for cardiovascular diseases.^37,38 Given the cross-sectional design of this study, longitudinal methodologies that assess early career mental and physical health in first responders and tracked over the course of a career are needed to elucidate these findings.

Furthermore, first responders in EMS roles may be more likely to experience anxiety symptoms compared with those in non-EMS roles, but similar associations were not found for depressive symptoms or alcohol use. A recent meta-analysis assessing global prevalence rates of mental health symptoms among first responders during the COVID-19 pandemic found that EMS personnel had high rates of anxiety-related disorders (28%).³⁹ Conversely and contrary to study hypotheses, first responders in EMS and non-EMS roles did not significantly differ across either depressive symptoms, alcohol use, or rates of probable clinical anxiety and depression. These findings were unexpected given the higher volume of calls and exposure to critical incidents typically faced by first responders in EMS roles⁴⁰ and the fact that such incidents were likely to exponentially increase during the COVID-19 pandemic.⁴¹ However, it is possible that first responders in non-EMS roles were required to respond to more medical calls because of personnel shortages as well as the substantial increase in call volume.^24,42 Overall, these findings are consistent with contemporary research,^20,21 highlighting that both EMS and non-EMS roles seem to be experiencing elevated mental health symptoms and alcohol use in light of the COVID-19 pandemic.

Significant interactive effects between CMV and first responder status on anxiety symptoms, depressive symptoms, and alcohol use severity emerged. Surprisingly and contrary to the study's hypotheses, post hoc simple slope analyses found that first responders in non-EMS roles with greater CMV evinced the highest levels of anxiety and depressive symptoms. Moreover, whereas first responders in non-EMS roles with greater CMV endorsed higher alcohol use, which coincides with extant literature on the negative impact of alcohol consumption on physical health,^37,38 those in EMS roles with greater CMV endorsed lower alcohol use. This result was unanticipated, given that both EMS personnel and firefighters tend to endorse greater levels of problematic alcohol use compared with the general population.⁴³ These finding should be considered in light of several possible considerations. First, the finding that first responders in EMS roles demonstrated lower alcohol sue severity is inconsistent with the literature.³ It may be that first responders in EMS roles were more likely to respond to the survey in the early stages of the pandemic; thus, we cannot rule out the effects of self-selection bias on study findings. It is also possible that first responders in EMS roles were less likely to consume alcohol because of increases in the number and length of shifts, frequency of mandated overtime, and overall reductions in personal time as a result of the pandemic.^23,24 Second, it is possible that firefighters experienced reduced access to personal protective equipment and/or less intensive training in mitigation of communicable disease transmission while on emergency calls, which may have increased COVID-19–related distress and in turn increased alcohol use. Thus, workplace programs that can improve attitudes toward and knowledge about mental health, along with wellness programs focused on improving physical health, can serve to address various psychological symptoms among first responders.^44,45

Although not the primary objectives of this study, a few additional findings are worthy of note. First, trauma load (ie, total number of traumatic event types endorsed) was significantly and positively associated with anxiety symptoms, which coincides well with previous literature.³ Second, years of service as a first responder was significantly and negatively associated with depressive symptoms and alcohol use severity, at univariate and bivariate levels. That is, first responders with more years of service were less likely to endorse elevated levels of depressive symptoms and reported lower frequency and quantity of drinking. Although the available research is mixed, years of service can serve as a protective factor for first responders, potentially via increased job satisfaction, coping skills, positive work-related outcomes, and perhaps greater resilience, which allows for longer career duration.²⁷ Finally, increased COVID-19 exposure (ie, direct and indirect types of exposure) was significantly associated with greater alcohol use, as first responders with higher rates of exposure were more likely to report elevated frequency and quantity of drinking. These findings are in line with previous work among health care personnel in past epidemics (eg, severe acute respiratory syndrome epidemic of 2003)⁴⁶ and extant research documenting increased alcohol use due to COVID-19–related stressors and exposure.²⁰

This study is not without its limitations. First, this study utilized a cross-sectional design and relied exclusively on self-administered measures among a convenience sample of first responders (ie, firefighters, EMS personnel, and law enforcement officers). Thus, we cannot infer causality or temporality among study variables, and self-selection and social-desirability biases may have impacted results. Second, the response rate was lower than expected, given the use of a large, national first responder service agency e-mail distribution list. The low response rate may have been due to the increased demands of work during the early stages of the pandemic for first responders.^23,24 Relatedly and because of the low response rate, the sample size for the current study is small and therefore warrants cautious interpretation of study findings and their clinical relevance. Because of the evolving stages of the pandemic and the national rollout of vaccines, responses to survey questions may also have differed across other stages in the pandemic, which may limit generalizability. Third, as this study was designed and implemented in the early stages of the COVID-19 pandemic, various measures used for purposes of the current study were either created or modified due to a lack of available COVID-19–related measures. Specifically, several of these measures were descriptive (eg, COVID-19 Exposure Questionnaire), whereas others included minor modifications to existing measures (eg, OASIS, ODSIS). Accordingly, future research should incorporate clinician-administered measures and/or well-established measures developed explicitly for pandemic-related research to extend these findings. Similarly, it is important to note that changing attitudes regarding the perceived risks of COVID-19 infection, particularly in the more recent phases of the pandemic, may also affect these findings. Fourth, although general medical vulnerability to COVID-19 complications was determined via self-report questions, information pertaining to the prevalence and types of specific health risks (eg, coronary heart disease, stroke, hypertension, obesity) among this sample is unknown, highlighting the need for more detailed assessments of medical history in extensions of this work. Fifth, the line between fire and EMS is not always clear, as the first unit on the scene of a medical emergency may be the first-due fire apparatus instead of the ambulance and require firefighters to provide immediate medical attention. In addition, some fire departments require EMS cross-training. Therefore, although participants were asked to self-report their role in EMS-related duties, it is possible that some first responders in the non-EMS subsample had some form of current or prior EMS experience in the field. Finally, the study's national sample primarily comprised White, non-Hispanic/Latino, male first responders. Because of the influence of sociodemographic factors on first responder mental health,⁴⁷ it is imperative for future research to recruit and include first responders who identify as women as well as those from racially and ethnically diverse backgrounds to extend these findings.

The COVID-19 pandemic has disproportionally affected those working on the frontlines. First responders' occupations carry inherent mental and physical health risks, and these risks have increased exponentially because of the pandemic. Study findings suggest that first responders with health risks that increase the likelihood of experiencing complications related to COVID-19 are more likely to experience anxiety and depressive symptoms. Moreover, these associations may vary based on whether a first responder provides direct EMS. Unfortunately, there is limited work examining prevalence rates and differences in mental illness and physical health across first responder populations, despite distinct differences in call volume and exposure to critical incidents across these groups. Thus, there is a need for future research to incorporate comprehensive assessments of physiological and psychological health history and job-related duties to further elucidate these findings and inform prevention approaches among first responders.