Introduction

In December 2019, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged and led to coronavirus disease 2019 (COVID-19), which rapidly spread globally. The COVID-19 pandemic caused significant disruptions in healthcare systems worldwide, particularly in emergency department (ED) utilization. Lockdown measures aimed at controlling viral spread led to substantial changes in healthcare-seeking behaviors, resulting in a marked decline in ED visits across various populations and regions [1,2].

Many studies have examined the effects of COVID-19 and lockdowns on ED trends, primarily by comparing pre-pandemic phases to lockdown periods. Research from multiple countries has documented significant declines in ED visits, affecting both adult and pediatric populations [3,4]. In the U.S., Hartnett et al. (2020) reported a 42% drop in ED visits during the lockdown, with the sharpest declines among children under 14. Fear of virus exposure, policy changes, and shifts in disease incidence due to social distancing and lockdown measures were major contributors to this decline [5].

In a low- and middle-income country (LMIC) like Lebanon, which has faced an ongoing financial crisis since late 2019 and where the Government Response Stringency Index reached 85, one of the highest in the world-strict lockdown measures contributed to a sharp decline in ED visits [6]. However, little research has been done on the changes in ED utilization and disease patterns that followed the lifting of lockdown measures, particularly in LMICs as opposed to high-income countries where most evidence originates. In Lebanon, our authors previously compared ED visits in Lebanon during the three months before the first identified COVID-19 case with the first three months of the pandemic, reporting a 47.2% decline in ED volumes, with the greatest drops among pediatric patients (67.8%). The steepest declines coincided with school closures and border lockdowns [7]. Compounding these challenges, the Beirut port explosion in August 2020 further strained Lebanon’s already fragile healthcare system during the lockdown period, representing an additional unmeasured stressor on ED utilization that is largely absent from studies conducted in high-income settings [8].

While several studies have compared ED utilization across pre-lockdown, lockdown, and post-lockdown phases, most have relied on aggregated surveillance data, often overlooking key demographic and socioeconomic factors that influence ED access and utilization. Additionally, many have been limited by short follow-up periods, small sample sizes, or a focus on either pediatric or adult populations with limited post-lockdown observation [9–11]. Also, most research done on post-lockdown visit trends explored presenting complaints or the primary reason for ED admission rather than final diagnoses [2,4,12,13]. Certain conditions, such as myocardial infarction, chronic ischemic heart disease, and coma, saw an increase in ED visits post-COVID-19 [14]. However, few studies have systematically documented final diagnoses using a standardized categorization framework [15]. Moreover, studies comparing lockdown and post-lockdown trends in both pediatric and adult ED visits in an LMIC setting, particularly with a focus on specific diagnoses, remain scarce. In resource-limited settings like Lebanon, where access to primary care is constrained by financial hardship and infrastructure gaps, the ED often serves as a primary point of care, making ED utilization data particularly informative for capturing post-lockdown care-seeking patterns, including potential catch-up visits among pediatric patients [7,16]

In this study, we analyzed variations in patient volumes and shifts in disease patterns among both adult and pediatric patients presenting to the ED during and after the COVID-19 lockdown at a Lebanese tertiary care center using the Clinical Classifications Software Refined (CCSR) criteria for categorization.

Materials and methods

Results

Table 1 presents a comparison of patient demographics and ED visit characteristics during and after lockdown. During the study period, 69,870 ED visits were recorded, with 28,972 visits occurring during the lockdown phase (Feb 29, 2020 – Mar 22, 2021) and 40,898 visits post-lockdown (Mar 23, 2021 – Apr 14, 2022). The average age of patients decreased significantly post-lockdown (41.7 ± 24.9 vs. 37.7 ± 25.7 years, p-value <0.001), driven by a significant rise in pediatric visits (from 17.4% to 23.9%, p-value <0.001). Daily ED visits significantly increased post-lockdown (85.5 ± 25.3 to 108.8 ± 16.9, p-value <0.001).

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Table 1. Comparison of patient demographics and ED visit characteristics between Lockdown and post- lockdown (N = 69,870).

https://doi.org/10.1371/journal.pone.0352275.t001

Post-lockdown, the gender distribution showed a statistically significant shift, with a slight decrease in the proportion of male visits (52.4% to 51.0%) and a corresponding increase in female visits (47.6% to 49.0%), p < 0.001. The ESI distribution shifted toward less acute presentations post-lockdown, with a significant decrease in ESI 2 cases (10.9% to 7.2%, p-value<0.001) and an increase in ESI 4 cases (3.2% to 7.4%, p-value <0.001). The mean ED length of stay slightly decreased post-lockdown (330.5 ± 755.7 vs. 319.2 ± 589.5 minutes, p = 0.02). Hospital admission rates declined post-lockdown (27.0% to 20.7%, p-value <0.001), and discharge rates increased (71.8% to 77.7%, p-value<0.001). Mortality rates remained low and stable, while the proportion of patients who left without being seen (LWBS) increased post-lockdown (0.1% vs. 0.6%, p < 0.001).

Table 2 presents an age stratified comparison of patient demographics and ED visit characteristics during and post-lockdown. The post-lockdown rise in daily visits was considerably more pronounced among pediatric patients, whose daily visits nearly doubled (16.6 ± 6.7 to 28.3 ± 8.7, p < 0.001), compared to a more modest rise among adults (68.9 ± 21.3 to 80.5 ± 12.3, p < 0.001). Among adults (n = 55,068), the mean age decreased slightly post-lockdown (49.1 ± 20.8 vs. 47.6 ± 21.3, p-value<0.001). The proportion of male visits decreased while that of female visits increased (52.1% to 49.5%, 47.9% to 50.5% respectively, p-value<0.001). Among pediatric patients (N = 14,802), by contrast, the proportion of male visits increased post-lockdown (53.7% to 55.7%) while female visits declined (46.3% to 44.3%, p = 0.02); a pattern opposite to that observed in adults.

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Table 2. Comparison of patient demographics and ED visit characteristics between Lockdown and post- lockdown stratified by age.

https://doi.org/10.1371/journal.pone.0352275.t002

Acuity shifted toward lower severity in both groups. Among adults, ESI 2 cases decreased from 10.8% to 7.0%, while ESI 4 cases increased from 3.1% to 7.2% with a p < 0.001. Similarly, among pediatric patients, ESI 2 declined from 11.4% to 7.9% and ESI 4 rose from 3.7% to 7.9% with a p < 0.001). Hospital admission rates declined in both groups (adults: 29.0% to 23.5%; pediatrics: 17.1% to 11.9%, p < 0.001 for both), with corresponding rises in discharge rates (adults: 69.7% to 74.9%; pediatrics: 82.0% to 86.7%). LOS diverged between the two groups: adult LOS decreased post-lockdown (347.9 ± 811.2 vs. 332.2 ± 627.1 minutes, p = 0.01), whereas pediatric LOS increased significantly (248.2 ± 387.2 vs. 277.7 ± 443.7 minutes, p < 0.001). Monthly ED visit trends for both groups are illustrated in Fig 1.

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Fig 1. ED visits monthly trend for adults and pediatrics.

Monthly ED visit volumes for adult and pediatric patients from March 2020 to March 2022. Both groups experienced a marked decline during the lockdown phase. Following the lifting of restrictions, pediatric visit volumes rose substantially before stabilizing. Adult volumes increased post-lockdown but continued to fluctuate throughout the observed recovery period. Annotated arrows indicate key events: General Mobilization, Beirut Port Explosion, Total Nationwide Lockdown, Vaccination Start, and Total Lifting of Lockdown. Total: total ED volume; AED: adult ED volume; PED: pediatric ED volume.

https://doi.org/10.1371/journal.pone.0352275.g001

Fig 1. illustrates monthly ED visit trends for adult and pediatric patients from March 2020 to March 2022. Both groups experienced a marked decline in visit volumes during the lockdown phase. Following the lifting of restrictions in March 2021, pediatric ED visits rose substantially, peaking in July 2021 before stabilizing. Adult ED volumes also increased post-lockdown but showed continued fluctuation without a sustained upward trajectory throughout the observation period.

Tables 3 and 4 show the percent change in visits by diagnosis as well as the odds ratios of presentation to the ED for a specific diagnosis during and post lockdown in pediatric and adult patients. Among pediatrics, the most prominent increases were seen in respiratory tract infections (303.3% increase; OR: 2.23, 95% CI: 1.95–2.56), diseases of the ear and mastoid process (343.37% increase; OR: 2.35, 95% CI: 1.85–2.99), and COVID-19 (354.84% increase; OR: 2.40, 95% CI: 1.82–3.17). Influenza also showed a notable numerical increase, though this did not reach statistical significance. A significant increase was also seen in other diseases of the respiratory system, injury and poisoning, diseases of the digestive system, diseases of the skin and subcutaneous tissue, and other viral infections. In contrast, certain infectious and parasitic diseases significantly decline (18.29 decrease; OR: 0.42 95% CI: 0.30–0.58), while mental, behavioral, and neurodevelopmental disorders did not exhibit significant changes.

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Table 3. Percent change in ED visits by diagnosis and corresponding OR (95% CI) post Lockdown compared to lockdown among pediatrics.

https://doi.org/10.1371/journal.pone.0352275.t003

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Table 4. Percent change in ED visits by diagnosis and corresponding OR (95% CI) post Lockdown compared to lockdown among adults.

https://doi.org/10.1371/journal.pone.0352275.t004

Among adults, diagnostic shifts were less pronounced. While respiratory tract infections did not show a statistically significant change among adults (63.64% increase; OR: 1.27, 95% CI: 0.75–2.16, p = 0.38), significant increases were observed in related respiratory categories, including influenza (47.0% increase; OR: 1.15, 95% CI: 1.06–1.24, p < 0.001) and other viral infections (61.4% increase; OR: 1.26, 95% CI: 1.12–1.41, p < 0.001). External causes of morbidity, diseases of the digestive system, and injury and poisoning-related visits, also showed significant increases. The most notable drops were in pregnancy, childbirth, and puerperium (24.7% decrease; OR: 0.58, 95% CI: 0.47–0.73, p < 0.001), COVID-19-related visits (10.4% decrease; OR: 0.68, 95% CI: 0.63–0.73, p < 0.001), and fever (7.6% decrease; OR: 0.71, 95% CI: 0.63–0.80, p < 0.001). Non-significant changes were observed in categories such as dental diseases, eye and adnexa diseases, musculoskeletal diseases, nervous system diseases, neoplasms, and skin diseases.

Discussion

This study observed ED trends during and after the COVID-19 lockdown at the largest tertiary care center in Beirut, Lebanon, revealing notable shifts in patient demographics, acuity levels, and disease presentations. A significant increase in overall ED volumes was observed post-lockdown, with a marked rise in pediatric visits. While adult ED visits also increased, the change was more moderate. High-acuity presentations declined across all age groups, while low-acuity cases rose. Diagnostically, pediatric patients showed substantial increases in respiratory tract infections, COVID-19, and ear and mastoid process diseases. Adult patients, on the other hand, showed significant increases in injury and poisoning, diseases of the digestive system, external causes of morbidity, and other viral infections and influenza, and notable decreases in COVID-19-related visits, pregnancy-related visits, and fever.

This study offers several methodological distinctions from existing literature. First, while prior research often focused exclusively on either the lockdown or pre-pandemic phases and evaluated shorter timeframes, typically lasting three to six months [18,19], our study spans both the lockdown and post-lockdown periods, covering a longer duration of nearly two years. Second, whereas most existing studies limited their analysis to either adult or pediatric populations [4,10,13,20], our study simultaneously assessed both groups allowing cross population comparison. Third, many previous studies grouped diagnoses into broad or custom categories without relying on standardized classification systems, limiting cross-study comparability [4,12,15]. In our study, we used CCSR to categorize diagnoses, which enhances the robustness of our findings. Finally, our inclusion of patient-level variables, such as age, sex, and financial guarantor as a proxy for socioeconomic status, adds further depth, contrasting with studies that rely primarily on surveillance data without linking clinical profiles to utilization trends [4,11,21].

Following the lifting of lockdown measures in Lebanon, pediatric ED visits rebounded sharply. This “catch-up” effect likely reflects both renewed transmission of communicable diseases following the reopening of schools and childcare centers, and previously deferred care during the stricter lockdown phase [9,18]. Similar rebound patterns have been reported internationally, including in Italy [9,18], the Netherlands [16], and the United States [10,21], where pediatric ED volumes recovered following the easing of restrictions. In the Netherlands specifically, ED volumes, including pediatric cases, rose as the Oxford Stringency Index (OSI) declined [16]. However, in contrast to the partial recovery seen in Dutch hospitals, where pediatric visits remained suppressed following the easing of restrictions [16], our data show a more rapid and robust post-lockdown rebound in pediatric ED volumes, which rose substantially and stabilized at higher levels by mid-to-late 2021. This more pronounced rebound may be due to limited full adherence to lockdown measures, and to the ED serving as the primary point of care for pediatric patients in Lebanon, making the post-lockdown surge fully captured in ED utilization data [7]. The divergence in post-lockdown recovery trajectories between pediatric and adult patients warrants further examination. The reopening of schools and childcare facilities likely played a key role by facilitating the spread of communicable diseases. In contrast to adults, whose COVID-19-related visits declined, possibly due to vaccination efforts, reduced ED testing, and widespread availability of at-home testing kits, pediatric COVID-19 visits rose, likely due to greater exposure in school environments and lower vaccination rates in children at the time. This difference in post-lockdown utilization patterns between children and adults is further reflected in the temporal trends observed in our data (Fig 1). Pediatric ED visits increased steadily following the easing of restrictions, peaking in July 2021, likely reflecting a compounded effect of seasonal summer surges and the post-lockdown rebound in communicable disease exposure, before stabilizing through the remainder of the observation period. In contrast, adult ED volumes showed a more gradual and fluctuating recovery throughout the post-lockdown period. Several factors may explain this slower adult recovery. Lebanon’s ongoing financial crisis, which predated the pandemic and intensified during it, likely deterred many adults from seeking non-urgent ED care due to increased out-of-pocket costs and reduced insurance coverage [22]. Persistent fear of infection, particularly among older adults with comorbidities, may have further suppressed ED utilization. Additionally, the expanded availability of telemedicine and outpatient alternatives during the post-lockdown period may have redirected some adult patients away from the ED for lower-acuity conditions [23]. Together, these factors may explain why adult LOS decreased post-lockdown, reflecting a shift toward less complex presentations, while pediatric LOS increased, likely due to higher volumes and crowding in the pediatric ED.

During the lockdown, fear of the virus caused many people to avoid seeking care, leading to delayed presentations at more advanced stages and higher severities [22]. However, after the lockdown was lifted and fear of the virus diminished, there was a shift in ED acuity levels. We observed a decrease in ESI 2 cases and an increase in ESI 4 visits, suggesting a rise in lower-acuity cases and conditions with less urgent needs. This change was also accompanied by an increase in cases related to bacterial infections and external causes like injuries. Additionally, there was a rise in discharge rates post-lockdown, likely reflecting the increase in lower-acuity visits, as people became more willing to seek care for conditions that typically require less intensive treatment and shorter ED stays.

Diagnostic patterns after lockdown varied noticeably between children and adults. Among children, there was a sharp rise in infectious diseases like respiratory tract infections and ear infections, likely driven by increased exposure to viruses in school and daycare settings. The concurrent surge across multiple pediatric infectious disease categories is further consistent with the concept of ‘immunity debt,’ whereby reduced exposure to circulating pathogens during the lockdown period led to waning immunity in the pediatric population, resulting in a broad post-lockdown surge in communicable diseases upon school reopening [24,25]. In contrast, adults showed a distinct pattern of diagnostic shifts, with fewer categories reaching significance compared to pediatrics. Significant increases were observed in injury and poisoning, digestive system diseases, external causes of morbidity, and other viral infections and influenza, while COVID-19-related visits, pregnancy-related visits, fever, and circulatory system diseases declined. The increases in injury, poisoning, and external causes likely reflect adults returning to work, commuting, and other activities that carry physical risk. The observed increases in other viral infections and influenza may additionally reflect post-COVID immune dysregulation, whereby prior COVID-19 infection may have increased susceptibility to other circulating pathogens [26], though our administrative dataset does not allow direct assessment of this relationship.

The significant fluctuations in ED visits and changes in patient demographics and disease spectrum underscore the difficulty of managing healthcare services during a pandemic. These fluctuations underscore the need for dynamic ED staffing and surge-capacity models that can be scaled up or down based on observed demand. In parallel, real-time ED surveillance dashboards (e.g., tracking arrivals, triage acuity, and key diagnostic syndromes) can help detect early shifts in volume and case-mix and support faster operational decisions during public health emergencies. To better prepare for future challenges, healthcare systems need flexible, adaptive strategies that can quickly respond to changing circumstances. With an increase in lower acuity visits post-lockdown, it is essential to strengthen healthcare capacity to manage these cases, perhaps through expanding outpatient care or telemedicine options. Investing in healthcare infrastructure and workforce training will ensure systems can handle surges during crises. Finally, preparedness plans should be in place to quickly scale services during public health emergencies, ensuring the system is always ready to meet evolving healthcare needs.

Conclusion

In conclusion, this study documents shifts in ED utilization patterns, patient demographics, and disease presentations during and following the COVID-19 lockdown period at a major tertiary care center in Lebanon. The marked post-lockdown rebound in pediatric visits, the divergent recovery trajectories between adult and pediatric populations, and the diagnosis-specific changes observed underscore the complexity of post-pandemic healthcare demand. These findings highlight the importance of continuous ED surveillance and flexible, adaptive resource allocation strategies to effectively manage healthcare systems during and after public health emergencies in resource-limited settings.