Epidemiologia, Volume 7, Issue 1 (February 2026) – 18 articles

Background/Objectives: The aging process is typically marked by a reduction in functional fitness, which heightens the likelihood of falling. Although obesity is established as a determinant of poor mobility, the interplay between excess weight and advanced age is still a topic of research interest. Therefore, this research investigated how age, sex, and Body Mass Index (BMI) interact to influence fall risk among older adults living in the community. Methods: This cross-sectional investigation involved 815 participants (M_age = 70.45 ± 6.10 years), stratified by age (sexagenarians, septuagenarians, octogenarians) and BMI (normal weight, overweight, obesity). Fall risk was assessed using the Timed Up and Go test. A Three-Way ANOVA examined the main and interaction effects. Results: No significant three-way interaction (p = 0.334) or main effect of sex (p = 0.079) was found. However, a significant age x BMI interaction was observed (p = 0.007). In sexagenarians and septuagenarians, obesity was associated with significantly slower fall risk performance compared to normal weight (p < 0.001). Conversely, in octogenarians, this difference was not significant (p = 1.000) with normal-weight individuals. Conclusions: Obesity may be a significant risk factor for falls, especially in adults aged 60 to 79 years. In octogenarians, the protective benefit of normal weight disappears, revealing a “weight paradox” likely driven by sarcopenia. Fall risk assessments and weight management strategies should be tailored to age, focusing on preserving muscle mass in octogenarians. Full article

Background/Objectives: Prostate cancer (PC) is one of the most commonly diagnosed malignancies globally; depending on the treatment strategy used, erectile dysfunction (ED) is a frequently reported adverse outcome among PC patients. The current study evaluated ED prevalence among Pakistani PC patients and its effects on physical, psychological, and social well-being, aiming to address critical gaps in survivorship care for this population. Methods: A cross-sectional, multicenter, observational, questionnaire-based study was conducted in Rawalpindi and Islamabad, Pakistan, from February to April 2025. Health-related quality of life (HRQoL) among PC patients was measured using the Short Form Health Survey 36 (SF-36), while ED prevalence and severity were assessed by the International Index of Erectile Function (IIEF) instrument. Results: Among N = 400 PC patients, surgical treatments predominated (radical prostatectomy: 61.0%; n = 244), while hormonal (androgen-deprivation therapy: 31.5%; n = 126) and chemotherapy (23.3%; n = 93) were also commonly utilized. ED experience was high among PC patients in the erectile function (40.8%; n = 163) and in the intercourse satisfaction (45.0%; n = 180) domains; these showed moderately strong and significant positive correlations across all SF-36 domains, particularly physical functioning (r = 0.52; p < 0.001) and social functioning (r = 0.49; p < 0.001). Regression analysis confirmed sexual function domains explained 60% of HRQoL variance (adjusted R² = 0.60). Conclusions: This study reveals high rates of treatment-related ED—and its biopsychosocial impact–among Pakistani PC patients, with significant negative impacts on HRQoL. The findings underscore the urgent need to integrate sexual health management into standard oncological care practices to improve holistic patient outcomes. Full article

Background/Objectives: Prostate cancer is the second most common cause of cancer-related mortality among the male population worldwide. It is among the leading reasons for the increasing number of years of life lost, working years of life lost, and gross domestic product (GDP) loss in Bulgaria. The primary objective of this study is to evaluate the burden of prostate cancer in Bulgaria, including calculating years of life lost (YLL), years of working life lost (YWLL), and the associated indirect costs. Methods: An observational time-series study was conducted using official national data from the National Statistical Institute (NSI), the INFOSTAT database, and the National Social Security Institute. The study covered the period 2008–2023 and included all registered male deaths attributed to malignant neoplasm of the prostate (ICD-10: C61). YLL, YWLL, and indirect costs were calculated using the human capital approach. Due to restricted access to age-specific mortality files, additional mortality records were obtained through formal data requests to NSI. Results: Prostate cancer led to 127,457 YLL and 6345 YWLL, with productivity losses reaching €88.2 million. Mortality showed an overall increasing trend up to 2020, while YWLL declined due to deaths shifting to older age groups. Conclusions: Despite the advancements in prostate cancer diagnosis and treatment, our findings demonstrate a negative trend regarding YLL, YWLL, and indirect costs associated with the disease, in contrast to other European countries. Strengthening early screening, reducing diagnostic delays, and improving national cancer registry capacity are critical to mitigating future health and economic losses. Full article

Background/Objectives: This ecological study aimed to investigate changes in the time-varying reproduction number (Rt) of SARS-CoV-2 across six regions of Massachusetts from 2020 to 2022 and to evaluate the impact of various nonpharmaceutical interventions (NPIs) implemented in 2020 by examining associated changes in the Rt. Methods: COVID-19 incident case data from the Johns Hopkins University database were adjusted for reporting delays using deconvolution and for underreporting via a Poisson-distributed multiplier of 4. Negative and zero counts were corrected using imputation. Rt was estimated using R package EpiEstim (Version 2.2-4) with a 7-day sliding window from 2020 to 2022 and with non-overlapping time windows between policy changes in 2020. Results: From 2020 to 2022, Massachusetts experienced five COVID-19 surges, linked to the wild-type strain and emerging variants, with Rt exceeding 1 during each wave and stabilizing at or dropping below 1 during low-incidence phases. School closure and gathering restrictions, the first major intervention, were associated with a 14.7% statewide reduction in Rt (95% credible interval (CrI): −23.6%, −5.6%), with greater reductions in high-density areas such as Boston (−16.9%; 95% CrI: −26.9%, −7.5%). No statistically significant changes in Rt were found to be associated with other NPIs in 2020, including the mask mandate, reopening phases, travel restrictions and quarantine requirements, and curfews. Conclusions: Our findings highlight the different NPIs’ varying impacts on COVID-19 transmission dynamics across regions in Massachusetts in 2020 and underscore the importance of early interventions for future pandemic preparedness. Full article

Background: Dementia is an increasing public health challenge in Mexico, yet recent national data on mortality patterns remain limited. This study examines temporal trends in dementia-related mortality and its sociodemographic and ecological characteristics among adults aged ≥65 years from 2017 to 2023. Methods: National mortality records from the General Directorate of Health Information were analyzed. Annual dementia-related mortality rates were calculated based on mid-year population estimates from CONAPO. Trends were assessed with regression analysis, including population offsets, and individual- and state-level characteristics were evaluated. Results: Between 2017 and 2023, dementia-related deaths increased from 761 to 1425, corresponding to an observed rise from 7.9 to 14.6 deaths per 100,000 inhabitants aged ≥65 years. Period trend indicated an average annual expected increase of 18.6% in dementia related mortality. A transient decline occurred in 2020–2021, coinciding with the COVID-19 pandemic. At the individual level, higher education was associated with greater odds of dementia certification, whereas Indigenous ethnicity appeared protective, which may reflect patterns consistent with diagnostic and reporting disparities. Higher state-level life expectancy correlated with higher dementia mortality, while greater population aging was inversely associated. Conclusions: Dementia-related mortality in Mexico shows a sustained upward trend with regional heterogeneity and apparent inequities in diagnosis and reporting. Strengthening mortality surveillance, improving certification quality, and integrating dementia indicators into national non-communicable disease registries are essential to guide equitable policy responses. Full article

Background/Objectives: Birth preparedness and complication readiness (BPCR) is a cornerstone of maternal health strategies designed to minimize the “three delays” in seeking, reaching, and receiving skilled care. In Ethiopia, uptake of BPCR remains insufficient, and little evidence exists on how individual- and community-level factors interact to shape preparedness. This study assessed the determinants of BPCR among women of reproductive age in Hawela Lida district, Sidama Region. Methods: A community-based cross-sectional study was conducted among 3540 women using a multistage sampling technique. Data were analyzed with multilevel mixed-effect negative binomial regression to account for clustering at the community level. Adjusted prevalence ratios (APRs) with 95% confidence intervals (CIs) were reported to identify determinants of BPCR. Model fitness was assessed using Akaike’s Information Criterion (AIC), the Bayesian Information Criterion (BIC), and log-likelihood statistics. Results: At the individual level, women employed in government positions had over three times higher expected BPCR scores compared with farmers (AIRR = 3.11; 95% CI: 1.89–5.77). Women with planned pregnancies demonstrated higher BPCR preparedness (AIRR = 1.66; 95% CI: 1.15–3.22), as did those who participated in model family training (AIRR = 2.53; 95% CI: 1.76–4.99) and women exercising decision-making autonomy (AIRR = 2.34; 95% CI: 1.97–5.93). At the community level, residing in urban areas (AIRR = 2.78; 95% CI: 1.81–4.77) and in communities with higher women’s literacy (AIRR = 4.92; 95% CI: 2.32–8.48) was associated with higher expected BPCR scores. These findings indicate that both personal empowerment and supportive community contexts play pivotal roles in enhancing maternal birth preparedness and readiness for potential complications. Random-effects analysis showed that 19.4% of the variance in BPCR was attributable to kebele-level clustering (ICC = 0.194). The final multilevel model demonstrated superior fit (AIC = 2915.15, BIC = 3003.33, log-likelihood = −1402.44). Conclusions: Both individual- and community-level factors strongly influence BPCR practice in southern Ethiopia. Interventions should prioritize women’s empowerment and pregnancy planning, scale-up of model family training, and address structural barriers such as rural access and community literacy gaps. Targeted, multilevel strategies are essential to accelerate progress toward improving maternal preparedness and reducing maternal morbidity and mortality. Full article

Background/Objectives: The COVID-19 pandemic caused over seven million deaths globally as of July 2024. In an attempt to bring the pandemic under control, immunization was implemented as the main preventive strategy. This study aimed to investigate the knowledge, attitudes, and practices (KAP) of hospitalized patients and healthcare workers (HCWs) regarding COVID-19 vaccination, as well as the factors contributing to COVID-19 vaccination rates. Methods: This cross-sectional, survey-based KAP study was conducted between November 2024 and February 2025 in five hospitals across five cities of the Republic of Srpska, Bosnia and Herzegovina. Results: There were 571 respondents, 68% of whom were female, with an average age of 39.17 ± 14.74 years; one-third held a university degree. The study sample consisted of patients and healthcare workers (HCWs) (59% vs. 41%). During the pandemic period, 46.6% of respondents were diagnosed with COVID-19, with a higher prevalence among healthcare workers compared to patients (54.2% vs. 41.2%). Among the 55.2% of respondents who were vaccinated, HCWs were more often vaccinated than patients (70.9% vs. 44.2%) and more likely to know that vaccines protect against severe forms of disease and death (80.8% vs. 68.5%). Patients more often believed that vaccination against COVID-19 may lead to sterility in young patients (11.3% vs. 6%) and were more often afraid of vaccination compared to the occurrence of COVID-19 (35.6% vs. 24.8%). Regression analyses showed that independent predictors of COVID-19 vaccination were older age (p < 0.001), higher education level (p = 0.039), knowledge of vaccine production technology, and the belief that vaccinated individuals have milder symptoms of the disease (p = 0.002). Conversely, the belief that the COVID-19 situation was overblown was negatively associated with vaccination (p = 0.004). Conclusions: HCWs had better knowledge, more positive attitudes, and better vaccination practices against COVID-19 in comparison to patients. However, there are still certain dilemmas and hesitations among HCWs toward COVID-19 vaccination. Full article

Background and objectives: During an outbreak, measles cases tend to aggregate into increasingly bigger clusters that show specific characteristics, different from the non-cluster cases. As the measles threat continues throughout Europe in 2025 with a high notification rate in Romania as well, exploring how clustering affects the disease propagation can provide additional insights into how to improve measles surveillance and control. Methods: National measles cases from 2020 to 2024 have been split into cluster (at least three related cases) and non-cluster-related cases and analyzed comparatively based on vaccination status, disease-related data (hospitalization) and patient-related data (age, location). Large outbreaks with at least 150 cases, allowing for more comprehensive R₀ analysis, have been described and the basic reproduction numbers computed for each of them. Results: There are statistically significant differences in vaccination status, age, and hospital stay between outbreak and non-outbreak cases. Large outbreaks (≥150 cases) show a high degree of variability, with R₀ values varying from as low to 1 to as high as 3.92, indicating limited measles transmission control. Conclusions: The findings in this research highlight the critical impact of clustering on measles transmission dynamics during outbreaks. Significant differences in vaccination status, age, and hospitalization rates between cluster and non-cluster cases underscore the importance of targeted surveillance and intervention strategies while the wide range of R₀ values observed in large outbreaks points to inconsistent control measures and emphasizes the need for strengthened vaccination campaigns and improved outbreak response protocols to better contain measles spread. Full article

Background/Objectives: Cardiovascular diseases (CVDs) remain a leading cause of mortality worldwide, with a particularly high burden in Central Asian countries. Despite ongoing urbanization, rural populations constitute a significant demographic in this region, yet epidemiological data stratified by urban and rural residence are limited and fragmented. This systematic review aimed to synthesize current evidence on the incidence, prevalence, mortality, and risk factor profiles of CVDs among urban and rural populations in Central Asia, identify disparities, and inform targeted prevention and control strategies. Methods: A systematic literature search was conducted across the PubMed, Science Direct, Web of Science, and Google Scholar databases for studies published between 2015 and 2025. Included studies reported cardiovascular health indicators with urban–rural stratification in Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan, and Turkmenistan. Data extraction and qualitative synthesis were performed, with methodological quality assessed using the Newcastle–Ottawa Scale. Results: Eight original studies met the inclusion criteria, encompassing national and regional datasets with diverse designs, including retrospective analyses, cross-sectional surveys, and registry data. Overall, CVD incidence and prevalence showed increasing trends in both urban and rural areas, with consistently higher mortality rates in urban populations. Key modifiable risk factors—hypertension, obesity, dyslipidemia, and smoking—were prevalent, particularly in rural settings. Variability in healthcare access and preventive program implementation contributed to the observed disparities. Limited data from some countries, particularly Tajikistan and Turkmenistan, highlight gaps in epidemiological surveillance. Conclusions: The cardiovascular disease burden in Central Asia demonstrates significant urban–rural disparities, underscoring the need for tailored public health interventions and enhanced healthcare resource allocation in rural regions. Strengthening epidemiological monitoring and implementing region-specific prevention programs targeting modifiable risk factors are imperative for reducing CVD morbidity and mortality. Further high-quality research is necessary to address existing data gaps and optimize cardiovascular health strategies across the region. Full article

Background/Objectives: Blood donation is essential to health systems and represents a valuable epidemiological model for studying physiological adaptation to controlled blood loss. Regular blood donors constitute a distinct, health-screened population whose biological responses offer unique insight into mechanisms of resilience and key determinants of population health. Hypoxia-inducible factor 1-alpha (HIF-1α) is a key regulator of erythropoiesis and cellular response to hypoxia, and its modulation following blood donation may inform donor safety and the sustainability of blood donation programs. This study aimed to characterize the sociodemographic, lifestyle, and anthropometric profiles of blood donors in relation to hematopoietic biomarkers (vitamin B12 and folic acid) and to evaluate changes in serum HIF-1α concentration after donation, emphasizing the public health relevance of voluntary blood donation. Methods: A cross-sectional study was conducted among 324 voluntary blood donors (159 regular and 165 occasional). Serum HIF-1α was measured before and 30 min after donation, together with vitamin B12 and folic acid levels. Sociodemographic and lifestyle characteristics (physical activity, smoking, dietary habits) were collected through standardized questionnaires (EHIS-3, FFQ), and anthropometric parameters were assessed. Results: Regular donors were older and predominantly male, with comparable socioeconomic indicators between groups. Both regular and occasional donors showed favorable lifestyle profiles, including low smoking prevalence and moderate physical activity. Skinfold thickness was significantly greater in regular donors (p < 0.001). The main biological finding was a robust post-donation increase in HIF-1α concentrations (≈80%, p < 0.001), independent of donation frequency or lifestyle. No significant associations were found between lifestyle factors and vitamin B12 or folate levels. Conclusions: Blood donation induces a rapid elevation in HIF-1α, reflecting activation of hypoxia-responsive pathways and short-term hematopoietic adaptation. Beyond its biomedical relevance, voluntary blood donation represents a meaningful epidemiological and public health model for studying physiological resilience and the health benefits of altruistic behavior. These findings underscore the importance of donor surveillance and motivation as components of broader preventive health and health equity strategies. Full article

Background/Objectives: Discovered in 2019, COVID-19 spread rapidly worldwide, leading from mild forms of the disease to critical forms or death, predominantly among vulnerable patients. Severity scores help clinicians in stratifying the risk of complications and death among patients diagnosed with SARS-CoV-2 infection. Methods: This study aims to identify the severity scores used in this type of infection, while bibliometric analysis carried out provided a comprehensive overview of global research patterns, trends, and cooperation in scientific literature on the chosen topic. Results: We conducted a literature screening to identify severity scores used in SARS-CoV-2 infection. Scores including CURB-54, COVID-GRAM, NEWS, APACHE II, SOFA, qSOFA, CALL, MuLBSTA, ISARIC 4C, and PADUA were identified with different performance indices. Conclusions: There were different results obtained depending on the geographical area of applicability, patient groups analyzed, and individual patient characteristics. Full article

Background/Objectives: To examine trends in tobacco and alcohol consumption among individuals with and without diabetes mellitus (DM) in Spain from 2014 to 2020 and identify sociodemographic, lifestyle, and comorbidity-related predictors of consumption. Methods: Population-based cross-sectional study using data from the 2014 and 2020 European Health Interview Surveys for Spain. Participants’ self-reported tobacco and alcohol consumption were analyzed based on DM status. Results: This study included 7854 participants (3927 participants with DM and 3927 participants without DM). Among participants with DM, tobacco and alcohol consumption remained stable over the study period, with tobacco from 15.2% in 2014 to 14.8% in 2020 (p = 0.761) and alcohol from 37.2% to 39.8% (p = 0.088), respectively. Tobacco consumption did not differ significantly between those with and without DM (15.0% vs. 15.2%, p = 0.777). However, alcohol consumption was significantly lower among those with than without DM (38.6% vs. 48.7%, p < 0.001). In those with DM, predictors of tobacco consumption included male sex, younger age, alcohol consumption, living without a partner, and DM, and predictors of alcohol consumption included male sex, active smoking, higher education, and sedentary lifestyle. Conclusions: Between 2014 and 2020, both tobacco and alcohol consumption remained stable among individuals with DM. The prevalence of alcohol consumption was lower among those with than without DM. Key predictors of tobacco and alcohol consumption included sex, lifestyle behaviors, and socioeconomic factors. These findings highlight the need for targeted public health interventions to reduce harmful substance use in DM populations and mitigate associated health risks. Full article

Aim: This study aimed to assess self-reported oral and orofacial health, hygiene habits, and oral health knowledge among Croatian athletes, and to determine factors influencing that knowledge. Differences between contact and non-contact sports, as well as the occurrence of dental trauma and temporomandibular joint (TMJ) symptoms, were also examined. Methods: A cross-sectional, questionnaire-based study was conducted among 1007 athletes (56% male, 44% female) aged 18–42 years, recruited through national sports federations and university sports clubs. The instrument comprised 85 items divided into five domains: sociodemographic data, oral hygiene habits, self-assessed oral health, TMJ symptoms, and oral health knowledge. Data were analysed using descriptive statistics, Chi-square and Fisher’s exact tests, and generalised linear modelling (p < 0.05). Results: Athletes demonstrated moderate oral health knowledge (mean score 11.3 ± 4.4/18). While 92.2% recognised that poor oral hygiene leads to caries and periodontitis, only 52.4% correctly identified the ideal time to replant an avulsed tooth. Female participants, older age groups, and those with higher education had significantly better knowledge (p ≤ 0.05). Recreational athletes scored higher than amateurs (p = 0.002), and those with prior dental trauma experience also showed greater awareness (p = 0.028). No significant difference was found between contact and non-contact sports (p = 0.287). Despite good brushing habits (86.9% brushed twice daily), only 25.4% regularly used dental floss or interdental brushes. A small proportion of athletes reported symptoms related to temporomandibular joint function, most commonly joint clicking (18.2%), tooth wear (13.4%), and nocturnal bruxism (14.3%). There were no significant differences between contact and non-contact sports, except for muscle stiffness near the temples (p = 0.024) and daytime or stress-related teeth grinding (p = 0.013 and p = 0.018). Conclusions: Croatian athletes demonstrated moderate oral health knowledge and satisfactory hygiene habits, but preventive practices remain inadequate. Education level, gender, and previous dental trauma were key determinants of knowledge. Systematic preventive programmes and targeted education are necessary to improve oral health awareness in sports populations. Full article

Background/Objectives: Per- and polyfluoroalkyl substances (PFAS) are globally widespread contaminants linked to adverse health outcomes, including immune dysregulation. We aimed to characterize PFAS exposure among adolescents in Nepal. We conducted a cross-sectional study in Chitwan District, Nepal, during September–October 2023, enrolling 73 adolescents from the Chitwan Birth Cohort. Methods: Dried blood spots from 48 participants were analyzed for 45 PFAS by liquid chromatography–tandem mass spectrometry. Sociodemographic and contextual behavioral covariates information (e.g., water source and local fish consumption) were collected via questionnaire. We used linear regression to analyze the association between contextual behavioral covariates and PFAS concentrations. Results: PFOS was detected in 46% of samples, followed by PFNA (25%) and PFOA (12.5%); other PFAS were rarely detected. Participants who consumed locally caught fish more than once per month had significantly higher PFOS levels (β = 0.35, p = 0.006). Conclusions: Frequent fish intake was the only factor significantly associated with PFAS levels, suggesting a dietary exposure pathway. This study provides the first documentation of PFAS exposure among Nepalese adolescents, revealing low-level exposures. Findings underscore the need for ongoing surveillance of environmental contaminants in vulnerable populations. Full article

Background: Molar–Incisor Hypomineralization (MIH) represents a developmental enamel defect of systemic origin, typically affecting the first permanent molars and often the incisors. Within the limitations of this study, several associations were observed between perinatal factors and MIH-related outcomes. However, most of these connections were not retained in adjusted analyses. Febrile illness during the first year of life showed a significant association with hypersensitivity. Methods: A structured 30-item questionnaire was distributed to mothers of 50 children diagnosed with MIH between February and March 2024. Data was analyzed using chi-square tests, with p < 0.05 considered significant, and univariate and multivariate logistic regressions at 95% confidence interval. Clinical diagnosis followed the Weerheijm (EAPD) criteria. Results: Maternal medication during pregnancy (antibiotics, antiepileptics, asthma drugs) was significantly associated with preterm birth (p = 0.01). Low birth weight correlated with tooth eruption disorders (p = 0.009) and perinatal complications such as hypoxia and respiratory distress (p = 0.0001). Fluoride application demonstrated a protective effect against discolorations (p = 0.005), caries (p = 0.002), and hypersensitivity (p = 0.01). In the multivariate model, febrile illness during the first year of life may be associated with hypersensitivity in MIH-affected teeth (aOR = 5.71, 95% CI: 1.01–32.27, p = 0.049). Conclusions: Maternal medication and perinatal complications, particularly low birth weight, were associated with MIH occurrence. Preventive strategies emphasizing maternal health, early screening, and remineralization-based therapies can mitigate long-term oral health impacts. Full article

Background/Objectives: The purpose of this study was to identify shared and differing characteristics of individuals testing for both SARS-CoV-2 and MPXV in 2022 in the greater Houston metro area. Methods: Data from the Houston Electronic Disease Surveillance System (HEDSS) identified 7,754,198 SARS-CoV-2 PCR lab results and 1246 MPXVV PCR lab results in 2022. Three cohorts for analysis were created where tests were performed, as follows: those positive for both viruses, those negative for COVID-19 but positive for MPXV, and those positive for COVID-19 but negative for MPXV. Results: We identified 88 individuals positive for both viral infections, those negative for COVID-19 but positive for MPXV (n = 38), and those positive for COVID-19 but negative for MPXV (n = 96). While groups were generally similar in regard to demographics (age, sex, and race) and risk factors reported, key differences in timing of testing and risk factors were reported. Notably, there was statistically significant difference in the time between t-tests for dual-infected individuals (99 days) compared to MPXV-positive only (58 days, p < 0.01) or COVID-19 positive only (63 days, p < 0.01). Conclusions: In the setting of multiple disease outbreaks, the characteristics of infected patients may be largely similar. Some people with dual infection may show unusual test results or symptom patterns compared with those with only one infection. Large public health studies with robust reporting systems and laboratory screening are vital for early detection of dual infections. Public health strategies to educate providers and outreach teams enhance response during concurrent outbreaks. Further research is needed on behavior and risk factors in communities with simultaneous outbreaks. Full article

Background/Objectives: The onset of infection in patients in contact with a COVID-19-positive index case in healthcare settings depends on intrinsic factors such as demographic factors, immune status, severity of underlying diseases, and comorbidities. Critical extrinsic factors for transmission, especially in hospitals, are length of exposure and distance. This study aimed to determine the risk factors of COVID-19 infections in contacts of COVID-19 index cases by conducting a prospective cohort study. Methods: The prospective cohort study included 186 index patients with confirmed COVID-19 and their 416 close hospital contacts. All contacts were followed for five days and tested using antigen or RT-PCR assays, with additional follow-up through national registries if discharged earlier. Results: The risk of infection was significantly higher in contacts older than 60 years (p = 0.009), in those hospitalised within orthopaedics and haematology departments (p < 0.001), and in patients whose bed was located within 1.5 m of the index case (p < 0.001). Laboratory findings showed significant associations with lower lymphocytes, glucose and higher potassium and creatinine levels, while other haematological and biochemical parameters did not differ. Hyperkalaemia (RR = 6.2 95%CI = 1.2–32.1 p = 0.30) and bed distance ≥ 1.5 m (RR = 0.3 95%CI = 0.2–0.6 p < 0.001) demonstrated an independent association with COVID-19 infection among contact patients. Conclusions: To reduce nosocomial transmission from unrecognised COVID-19 reservoirs, patients with electrolyte imbalance and lower levels of blood elements should be placed at a greater distance of 1.5 m from others, especially patients in haematology departments. Full article

Background and Objective: Evaluating vaccine effectiveness (VE) is essential to implementing prevention strategies, and our objective was to estimate the VE of SARS-CoV-2 messenger RNA (mRNA) vaccines in preventing SARS-CoV-2 infection. Materials and Methods: We carried out a population-based, prospective cohort study on the Borriana COVID-19 cohort (Valencia Community, Spain) during the 2021–2023 period, considering all SARS-CoV-2 cases that occurred after the SARS-CoV-2 vaccine campaign started in January 2021 (first approach), as well as only symptomatic cases (second approach). Multivariable robust Poisson regression models were employed. Results: In this cohort with 301 participants, 285 were vaccinated, among whom 228 received only SARS-CoV-2 mRNA vaccines, and 57 received mRNA vaccines and other vaccines. In the first approach, there were 226 cases and 75 non-cases. The adjusted VE for three doses of vaccine was 37% (95% confidence interval [CI]: 22–49%) to prevent infection. In the second approach, with 153 symptomatic cases after excluding 73 asymptomatic cases, the adjusted VE for three doses of vaccine was 50% (95% CI 33–63%) to prevent symptomatic infection. Three doses of vaccine exhibited modest but significant protection against infection and symptomatic infection. Conclusions: This study recommends surveilling SARS-CoV-2 infections and variants, vaccinating at-risk populations, and developing new vaccines. Full article