COVID, Volume 6, Issue 4 (April 2026) – 16 articles

Background: The COVID-19 pandemic increased stress experienced by children through individual-, family-, and community-level factors, with potential sex-specific impacts on behavioural outcomes. Children’s resilience may buffer these effects. This exploratory study investigated associations between COVID-19 stress and children’s internalising, externalising, and overall behavioural symptoms, and whether child resilience and sex assigned at birth moderated these associations. Methods: Data (N = 68) came from the longitudinal COVID-19 Impact Study of the Canadian APrON pregnancy cohort of mothers and their children followed for more than 9 years. COVID-19 stress, combining individual-, family-, and community-level stressors, was reported by mothers (mean age = 42.37, SD = 3.72) and their children (53% female; mean age = 10.21 years, SD = 0.43) across three timepoints (October–December 2020; February–May 2021; June–August 2021). Children’s behavioural problems and self-reported resilience were assessed between April and September 2022. Results: COVID-19 stress was not significantly associated with children’s behavioural problems. Moderated-moderation suggested that the association between COVID-19 stress and children’s internalising (T-score estimate = −2.38, 95% CI [−4.08, −0.68]), externalising (T-score estimate = −3.21, 95% CI [−5.09, −1.33]), and overall (T-score estimate = −2.79, 95% CI [−4.45, −1.12]) symptoms may vary by child resilience and child sex assigned at birth. Among females, COVID-19 stress appeared to be associated with more behavioural problems at lower levels of resilience and fewer problems at higher levels of resilience. Significance: The association between COVID-19 stress and children’s behavioural symptoms across children’s resilience levels may vary based on sex assigned at birth, with effects suggested among females. Null findings may reflect the modest sample size and limited statistical power. Full article

This study evaluates the performance of a semi-dynamic negative binomial model with cubic spline smoothing to characterize the spatiotemporal dynamics of COVID-19 mortality in Peru, a setting marked by significant data inconsistency and reporting delays. Using nationwide weekly mortality data, we compared a Poisson regression against a semi-dynamic NB model with a population offset and cubic splines (df = 6). The models were evaluated using Akaike Information Criterion and log-likelihood to handle overdispersion and temporal non-stationarity. The NB model demonstrated a superior fit, reducing the AIC from 136,596.4 to 75,668.25 and improving log-likelihood by over 30,000 points. Demographic analysis revealed an 81.6% higher risk of death in males (IRR = 1.816; 95% CI: 1.753–1.881) and an exponential gradient with age, peaking at an IRR of 4.717 (95% CI: 4.499–4.945) for individuals ≥80 years. Departmental fixed effects identified significant spatial heterogeneity, with higher diffusion in coastal regions. The semi-dynamic NB model with splines provides a robust, parsimonious, and scalable framework for epidemiological surveillance in resource-limited settings. By effectively correcting for overdispersion and stabilizing weekly reporting fluctuations, this approach offers a reliable tool for public health decision making in environments with fragmented data quality. Full article

Background: Religious affiliation has traditionally served as a coping strategy during stressful events such as the COVID-19 pandemic. Pregnant women faced heightened stress during the pandemic due to concerns about their health as well as that of their fetus. This study examined the prevalence of self-reported religious affiliation among SARS-CoV-2-positive pregnant women and investigated differences in psychiatric diagnoses and pregnancy outcomes based on religious affiliation. Methods: The study included all asymptomatic or mildly symptomatic SARS-CoV-2-positive pregnant women who received care at the Mayo Health System from March 2020 through October 2021 and completed the routine religious affiliation questionnaire. Those selecting “none” were categorized as having no religious affiliation (RA−), whereas those selecting a specific religion were categorized as religiously affiliated (RA+). Results: Among 609 women, 49.6% were RA+ and 50.4% were RA−. RA+ women were more likely to be white, married, college-educated, and have fewer prior abortions. There were no significant differences in rates of depression, anxiety, psychotropic medication use, substance use, or pregnancy and labor complications between RA+ and RA− groups. Conclusions: Half of the women in this cohort reported no religious affiliation. Previously reported protective associations between religiosity and mental health were not observed when religious affiliation alone was examined. Full article

Background and Objective: After SARS-CoV-2 infection, Long COVID (LC) syndrome has occurred in a high proportion of patients, affecting their health. The aim of this study was to estimate the incidence of LC, as well as its risk and protective factors. Materials and Methods: We conducted a prospective population-based cohort study of the Borriana COVID-19 cohort (Castellon Province, Valencia Community, Spain) from May 2020 to August 2023, with a follow-up of 40 months, using the LC definition given by the World Health Organization. Inverse probability-weighted regression adjustment was applied in the statistical analysis. Results: With a participation rate of 63.8% and a total of 722 participants, the mean age was 37.7 ± 17.4 years, and 460 (62.3%) were female. Among them, 644 had experienced a SARS-CoV-2 infection, and 184 developed LC, corresponding to a cumulative incidence of 28.6%. At the time of follow-up, 135 patients remained affected by LC, and one LC-related death was recorded. Significant risk factors for LC included older age, female sex, being part of a small family, having a chronic disease, SARS-CoV-2 exposure, and disease severity. Asymptomatic COVID-19 infection and SARS-CoV-2 vaccination were significantly protective factors. Conclusions: A substantial incidence of LC was observed, along with a low recovery rate. Several risk and protective factors were identified. Continued follow-up of this cohort, improved medical care for patients with non-recovered LC, ongoing surveillance of SARS-CoV-2 infections, and vaccination of the at-risk populations against SARS-CoV-2 are recommended. Full article

Background: The clinical course of COVID-19 is highly variable, ranging from asymptomatic infection to critical illness with hyperinflammation and multiorgan failure. Oxidative stress plays a central role in COVID-19 pathogenesis, and genetic polymorphisms in glutathione S-transferase (GST) enzymes, particularly GSTM1 and GSTT1 null genotypes, may impair antioxidant defense and exacerbate inflammatory responses. This study aimed to investigate the association of GSTM1 and GSTT1 null genotypes with both disease severity and serum cytokine levels in hospitalized COVID-19 patients. Methods: This cross-sectional study enrolled 137 COVID-19 patients hospitalized during the second pandemic wave (July–September 2020). Patients were stratified into mild (n = 67) and severe (n = 70) groups based on clinical criteria. GSTM1 and GSTT1 polymorphisms were determined by multiplex polymerase chain reaction. Serum levels of 13 cytokines were measured using flow cytometry. Logistic regression analyzed genotype associations with disease severity, and multivariate linear regression assessed relationships between null genotypes and pro-inflammatory cytokine levels (IL-6, TNF-α, IL-17A, IFN-γ), adjusted for age, sex, hypertension, and diabetes. Results: The GSTT1 null genotype was significantly associated with severe COVID-19 (adjusted OR = 2.56, 95% CI: 1.08–6.07, p = 0.032). Severe patients exhibited significantly elevated levels of IL-6 (75.6% increase, p = 0.008), TNF-α (69.4% increase, p = 0.005), IL-17A (54.4% increase, p = 0.016), and IFN-γ (10.1% increase, p = 0.021). Both GSTM1 and GSTT1 null genotypes were associated with higher levels of these cytokines, with stronger effects observed for GSTT1 null. In multivariate analysis, GSTT1 null independently predicted elevated IL-6 (β = 52.6, p = 0.003), TNF-α (β = 13.8, p = 0.002), IL-17A (β = 2.4, p = 0.001), and IFN-γ (β = 56.4, p = 0.012). The combined both null genotype showed the strongest associations but was limited by small sample size (n = 10) and should be interpreted with caution. Conclusions: The GSTT1 null genotype is associated with severe COVID-19 and appears to be associated with heightened pro-inflammatory cytokine responses, particularly IL-6, TNF-α, IL-17A, and IFN-γ. These findings suggest a potential role for genetic impairment of antioxidant defense may contribute to hyperinflammation in COVID-19 hyperinflammation, although validation in larger cohorts is needed. Full article

Coronavirus disease-2019 COVID-19 exhibits marked inter-individual variability in susceptibility and clinical outcomes, suggesting a role for host genetic factors. Vitamin D exerts immunomodulatory effects through the vitamin D receptor (VDR), and genetic variation in the VDR gene may influence host responses to SARS-CoV-2 infection. This study aimed to investigate the association between VDR-gene polymorphisms—FokI (rs2228570), TaqI (rs731236), ApaI (rs7975232), and BsmI (rs1544410)—and COVID-19 susceptibility in the Kurdish population. The FokI polymorphism was significantly associated with COVID-19 susceptibility. Interestingly, the GG-genotype was more frequent among Patients than controls and was associated with increased odds of infection (OR = 9.00; 95% CI: 3.22–25.15; p < 0.0001), whereas the AG-genotype was associated with reduced susceptibility (OR = 0.33; 95% CI: 0.14–0.76; p = 0.001). Additionally, the G-allele was also more prevalent in Patients than controls (OR = 1.87; 95% CI: 1.21–2.89; p = 0.004). Similarly, the TaqI TT-genotype was more frequent among Patients and was associated with increased susceptibility (OR = 36.0; 95% CI: 11.2–115.8; p < 0.0001). In contrast, the ApaI AA-genotype was less frequent among Patients and was associated with reduced odds of COVID-19 susceptibility under a recessive model (OR = 0.15; 95% CI: 0.03–0.68; p = 0.003). Moreover, the BsmI polymorphism was monomorphic in both groups and therefore not informative. Genetic variation in the VDR gene, particularly at the FokI, TaqI, and ApaI loci, was associated with COVID-19 susceptibility in the case–control study, while BsmI showed no variations. These findings suggest that genetic variation in the VDR gene may contribute to inter-individual differences in susceptibility to SARS-CoV-2 infection in the Kurdish population. Larger studies incorporating functional validation and detailed clinical data are required to confirm these associations. Full article

Health crises hinder the provision of intensive care for critical obstetric conditions such as preeclampsia and eclampsia, where timely decision making and system capacity directly impact maternal and fetal outcomes. This study compared the clinical and epidemiological profile and care processes in the ICU for cases of preeclampsia and eclampsia before and during the COVID-19 health crisis in Alto Amazonas, Loreto (Peru), using a comparative mixed-method approach. Quantitative data were obtained from ICU medical records for two periods (2015–2019 and 2020–2022). Categorical variables were compared using exact methods (Fisher’s exact test for 2 × 2 tables and exact procedures for scatter tables with multiple categories), and continuous variables were compared using nonparametric tests where appropriate. The most notable change was an increase in the frequency of cesarean sections during the health crisis, which should be interpreted with caution given the small sample size and potential changes in admission criteria and system limitations. Other clinical indicators and discharge status showed no clear evidence of substantial differences between the periods. Qualitative findings highlighted systemic limitations affecting continuity of care, particularly those related to timely access to safe blood products and referral pathways. These results align with SDG 3 (Good Health and Well-being) and support strengthening preparedness, referral coordination, and the availability of essential resources to protect maternal health during large-scale emergencies. Full article

The concurrent occurrence of COVID-19 and the 2024 Noto Peninsula earthquake resulted in a “compound disaster” in Japan. This retrospective study, spanning 11 years (2015–2025), examines the impact of these crises on trends in cardiovascular surgery, focusing on infective endocarditis (IE). A total of 2444 surgical cases were analyzed across three distinct periods: pre-pandemic (2015–2019), pandemic (2020–2023), and compound disasters (2024). While overall surgical volumes exhibited fluctuations, there was a notable increase in the number of interventions for IE and renal failure in 2024. Additionally, the 2024 IE cohort revealed a significant epidemiological shift, characterized by a younger median age (56 years compared to 70 years pre-pandemic), absence of pre-existing valvular disease, and a marked rise in blood culture-negative endocarditis (BCNE), which accounted for 83.3% of IE cases. In 2025, the number of surgical IE cases decreased to zero, highlighting the acute nature of the peak in 2024. These findings illustrate that compound disasters can disrupt cardiovascular surgical trends and underscore the susceptibility of IE to compromised healthcare access and environmental stress. The development of resilient diagnostic pathways is essential for managing complex public health emergencies. Full article

Previous studies have suggested that the COVID-19 pandemic exposed children to an increased risk of greater body weight accumulation; however, the evidence found is limited to examining relatively short periods in children from Asian, European, and North American countries and, in most cases, using cross-sectional designs, while studies with longitudinal designs are scarce. To our knowledge, to date, no study involving Brazilian children has examined temporal trends in body weight during the pandemic period using a longitudinal approach. Objective: To report the weight status of children aged 6 to 11 years pre-, during, and post-school closures in response to restrictions imposed by the COVID-19 pandemic, using a six-year school-based longitudinal cohort design (2020–2025). Method: Weight status was analyzed using the body mass index and diagnostic criteria proposed by IOFT. Initial data collection took place in 2020 (baseline—pre-school closures), in 2021 and 2022 (pandemic period—school closures), and in 2023, 2024, and 2025 (post-pandemic period—after the reopening of schools). Results: The data collected confirmed that restrictions imposed to mitigate the adverse impact of the COVID-19 pandemic, including the full or partial closure of schools, substantially increased children’s weight above what would be expected for their gender and age. After two years of the pandemic period, 23% of children identified in the baseline pre-school closures with normal body weight migrated to overweight, while 34% of overweight children became obese. Data equivalent to the post-pandemic period showed signs of a reduction in the excess body weight accumulated during the pandemic; however, the prevalence rates of overweight and obesity remained significantly higher than pre-school closures. Conclusions: The findings suggest that the harmful effects contributing to the greater accumulation of body weight during the COVID-19 pandemic tended not to reverse spontaneously, even five years after its onset. Therefore, specific actions to prevent, combat, and control overweight and obesity are essential to avoid present and future adverse consequences for children’s health. Full article

For vaccine-preventable diseases, vaccination uptake is among the best public health behaviors to prevent infection, disease and death. However, public confidence in this behavior has waned in recent years alongside the twin respiratory threats of influenza and COVID-19. Moreover, certain populations, such as emerging adults, may be amenable to vaccination attitude and behavior change as they navigate their path between adolescence and adulthood. The current investigation presents two studies that address influenza and COVID-19 vaccination uptake among emerging adults. First, among more than 2000 emerging adults during the years of 2022–2024, we examined rates of vaccination uptake and attitudes, as well as relationships of vaccine rates with other concomitant health behaviors. Second, we explored the efficacy of a classroom-based vaccination promotion experience in altering both attitudes and behaviors regarding vaccination uptake among 275 emerging adults at college. Results highlighted some health behaviors that are related to influenza uptake but not COVID-19 uptake. Moreover, results from Study 2 demonstrated that attitudes, but not behavior, seem to be most amenable to the classroom-based approach to encourage health behavior change, as a significant increase in positive attitudes toward both influenza and COVID-19 vaccines was observed. These findings are discussed further, considering theoretical and practical applications. Full article

Objective: Dental professionals are routinely exposed to infectious agents through contact with blood, saliva, and aerosols. This cross-sectional survey aimed to evaluate and compare knowledge, attitudes, and self-reported practices related to infectious diseases among dental students and practicing dentists in the post-COVID era. Methods: This web-based cross-sectional survey was conducted between January and March 2024 at a single dental faculty. Fourth- and fifth-year dental students and practicing dentists were invited to participate. A 30-item questionnaire assessed knowledge of infectious disease transmission and immunological markers (Questions Q1–Q19), as well as attitudes and self-reported practices toward patients with infectious diseases (Q20–Q30). Descriptive statistics were calculated, and comparisons between groups were performed using Pearson’s chi-square or Fisher’s exact tests (α = 0.05). Internal consistency of the questionnaire was acceptable (Cronbach’s alpha: 0.81 for knowledge items and 0.88 for attitude/practice items). Results: A total of 221 dental students and 33 dentists were included in the final analysis. Both groups demonstrated high awareness of respiratory transmission routes for COVID-19 and influenza. In contrast, recognition of bloodborne transmission pathways was limited, with approximately half of participants identifying blood contact and blood-contaminated instruments as potential sources of infection. Significant differences were observed between students and dentists in the interpretation of SARS-CoV-2 IgG antibodies, with dentists more frequently associating IgG positivity with prior infection (p = 0.009) and immunity (p < 0.001). Cautious behavior toward treating patients with infectious diseases was common in both groups, whereas reluctance to provide treatment and lower self-perceived knowledge were more frequently reported among students. Conclusions: Despite adequate awareness of respiratory infection transmission, important deficiencies persist in bloodborne pathogen knowledge, serological interpretation, and confidence in managing infected patients, particularly among dental students. These findings underscore the need for targeted, practice-oriented infection control education that integrates immunological principles and hands-on training to enhance clinical preparedness in the post-COVID era. Full article

COVID-19 is increasingly recognized as a multisystemic disease with significant neurocognitive consequences. However, its specific impact on spatial memory, a cognitive domain essential for daily navigation and functional independence, remains insufficiently explored. This narrative review provides a critical synthesis of current evidence regarding spatial and visuospatial memory alterations across acute and post-acute phases, and post COVID-19 condition (PCC). Clinical findings, conventional and emerging assessment tools ranging from static tasks to immersive virtual reality environments, as well as potential neurobiological mechanisms, were considered. Results suggested that spatial memory is frequently compromised after COVID-19 disease, with deficits being most pronounced at longer retention intervals and within navigational contexts. Neuroimaging and biomarker data further reveal selective vulnerability in the medial temporal lobe, characterized by hippocampal atrophy, hypoperfusion, and disrupted functional connectivity. Importantly, traditional neuropsychological tools may underestimate these impairments due to limited ecological validity. Therefore, implementing multimodal assessment frameworks that integrate navigational paradigms is essential to enhance diagnostic sensitivity and facilitate the development of targeted rehabilitation strategies for PCC patients. Full article

Background: The COVID-19 pandemic has been associated with increased psychological distress globally. However, the independent psychological impact of prior COVID-19 infection remains heterogeneous, particularly in primary healthcare populations. This study aimed to examine differences in anxiety and depressive symptoms between individuals with and without a history of COVID-19 infection in a primary healthcare setting. Methods: A cross-sectional study was conducted in April 2022 in five family medicine practices in the primary health care facility of Sarajevo Canton. A total of 279 participants without previously diagnosed mental disorders completed an online questionnaire. Anxiety and depressive symptoms were assessed using the GAD-7 and PHQ-9 scales. Multivariable regression models were performed, and propensity score matching (1:1 nearest-neighbor matching, caliper = 0.2) was conducted to address baseline imbalance. Results: No statistically significant independent association was detected between prior COVID-19 infection and anxiety or depressive symptoms in multivariable models. Propensity score matching yielded 84 well-balanced pairs. In the matched sample, no significant differences were observed in GAD-7 (p = 0.229) or PHQ-9 scores (p = 0.139), nor in clinically relevant cut-offs. Female sex and chronic disease were independently associated with higher anxiety levels. Conclusions: In this primary healthcare population, we did not observe an independent association between prior COVID-19 infection and anxiety or depressive symptoms after covariate adjustment and propensity score matching. These findings should be interpreted cautiously given the cross-sectional design, possible exposure misclassification, and residual confounding. Full article

The COVID-19 pandemic transformed healthcare education, increasing the shift to digital tools and establishing a hybrid curriculum blending online learning with traditional clinical practice. This study aims to understand how this shift impacts the educational growth and skill building of nursing students. A qualitative approach was conducted to understand the experience of Hong Kong nursing students adapting to online learning during the pandemic and beyond. Fifty nursing students were interviewed, and Colaizzi’s phenomenological method revealed key themes in their learning narratives. The analysis revealed four distinct themes characterizing the students’ experiences: (i) Learning on their terms: the mandated shift in healthcare reflecting a lack of agency during the educational transition; (ii) Knowledge without touch: the perceived incompetence of the COVID-19 nursing cohort, highlighting anxieties regarding a lack of hands-on clinical proficiency; (iii) Words left unsaid: The weight of insecurity, indicating a decline in interpersonal skills due to isolation; and (iv) Beyond the perfect algorithm: the unrehearsed art of care, describing the difficulty in translating digital simulations to complex, human-centric patient care. Findings show that while digital progress ensured continuity in education, it also contributed to reduced clinical confidence, weaker communication skills, and shifts in how nursing students approached their learning. Consequently, the post-COVID environment demands that training programs evolve to address these specific deficits. Advancing the existing pandemic-era nursing literature, this study emphasizes the need for diverse, targeted teaching methods to mitigate these gaps. By intentionally bridging theoretical knowledge with hands-on clinical practice, educators can better support student wellbeing and help restore the confidence and competence required of future graduates. Full article

The neuroinvasive and neurotropic character of coronaviruses is a likely reason for neurological complications which may occur during acute COVID illness and sometimes persist or newly emerge in the post-acute phase. Terminology and temporal classification remain heterogeneous. A retrospective case series was conducted in a single center (Department of Neurology, Bielański Hospital, Warsaw, Poland). Medical records from March 2020 to December 2023 were screened. Inclusion criteria: (1) confirmed SARS-CoV-2 infection (polymerase chain reaction or antigen test and radiological findings), (2) new neurological syndrome within acute, post-acute, or post-COVID interval, and (3) diagnostic documentation. Exclusion criteria: alternative established etiology fully explaining the neurological condition. Six cases were selected for detailed analysis due to diagnostic completeness as well as etiological and temporal diversity. Cases included: (1) persistent neurocognitive and sensory symptoms (post-COVID), (2) acute ischemic stroke with internal carotid artery dissection during severe COVID-19, (3) cytotoxic lesion of the corpus callosum (CLOCC) during acute COVID-19, (4) Guillain–Barré syndrome (post-acute), (5) longitudinally extensive transverse myelitis (post-acute), and (6) delayed autoimmune cerebral vasculitis (post-COVID). Neurological presentations ranged from mild persistent symptoms to fatal outcome. Neurological complications span inflammatory, vascular, and autoimmune mechanisms across distinct temporal phases of SARS-CoV-2 infection. Precise temporal classification and systematic diagnostic protocols are essential. Prospective longitudinal studies integrating biomarkers and standardized neuroimaging are required. Full article

Objectives: While the previous literature has established that meteorological conditions are associated with COVID-19 mortality fluctuations, the relative effect of each of these highly correlated factors remains unclear. This study aims to conduct a comparative analysis to determine which of three main meteorological variables—Ambient Temperature, Ultraviolet (UV) Index, and Sunlight Duration—have the strongest negative association with COVID-19 mortality. The objective is to quantify and rank their impact over a 7-to-21-day biological exposure window. Methods: We conducted retrospective spatiotemporal analyses in the form of panel Poisson Distributed Lag Models (PDLMs) regression using daily data from 21 January 2020 to 10 January 2023, spanning 129 distinct geographical regions worldwide. To ensure a direct and fair comparison of effect sizes, all meteorological and environmental variables were Z-score standardized. We estimated three independent PDLMs—each focusing separately on UV Index, Ambient Temperature, and Sunlight Duration—with lags ranging from 7 to 21 days. These models controlled for overarching time trends and utilized a categorical variable to account for Region Fixed Effects modeling time-invariant regional health and socioeconomic determinants (e.g., obesity, age demographics, healthcare capacity). Furthermore, distributed lags of daily PM2.5 (air pollution) and relative humidity were explicitly included in each model as dynamic confounders. Results: The comparison of PDLM results reveals that the UV Index has the strongest negative association with COVID-19 mortality. A one standard deviation increase in the UV Index corresponds to a massive, highly significant cumulative reduction in deaths observed 1 to 3 weeks later (p < 0.001). Sunlight Duration is the second-strongest protective meteorological factor, whereas Ambient Temperature has the weakest effect. The distributed lags of particulate matter (PM2.5) and relative humidity were found to be statistically insignificant when modeled alongside the meteorological variables. Conclusions: After standardizing variables and controlling for dynamic environmental confounders like air pollution and humidity, the study findings provide robust empirical evidence that meteorological conditions have a strong significant association with COVID-19 mortality fluctuation with a temporal delay, overcoming the confounding effects of merely dry or clear-air conditions. Full article