Oxidative Damage and Post-COVID Syndrome: A Cross-Sectional Study in a Cohort of Italian Workers.

In addition to the acute symptoms after infection, patients and society are also being challenged by the long-term effects of COVID-19, known as long COVID. Oxidative stress, as a pivotal point in the pathophysiology of COVID-19, could potentially be also involved in the development of the post-COVID syndrome. The aim of the present study was to evaluate the relationship between changes in oxidative status and the persistence of long-COVID symptoms in workers with a previous mild COVID-19 infection. A cross-sectional study was conducted among 127 employees of an Italian university (80 with a previous COVID-19 infection, and 47 healthy subjects). The TBARS assay was used to detect malondialdehyde serum levels (MDA), while total hydroperoxide (TH) production was measured by a d-ROMs kit. A significant difference in mean serum MDA values was found between previously infected subjects and healthy controls and (4.9 µm vs. 2.8 µm, respectively). Receiver-operating characteristic (ROC) curves showed high specificity and good sensibility (78.7% and 67.5%, respectively) for MDA serum levels. A random forest classifier identified the hematocrit value, MDA serum levels, and IgG titer against SARS-CoV-2 as features with the highest predictive value in distinguishing 34 long-COVID from 46 asymptomatic post-COVID subjects. Oxidative damage persists in subjects with previous COVID-19 infection, suggesting a possible role of oxidative stress mediators in the pathogenesis of long COVID.

Mesothelioma Risk among Construction Workers According to Job Title: Data from the Italian Mesothelioma Register.

BACKGROUND: An increased risk of mesothelioma has been reported in various countries for construction workers. The Italian National Mesothelioma Registry, from 1993 to 2018, reported exposure exclusively in the construction sector in 2310 cases. We describe the characteristics of these cases according to job title. METHODS: We converted into 18 groups the original jobs (N=338) as reported by ISTAT codes ('ATECO 91'). The exposure level was attributed at certain, probable and possible in accordance with the qualitative classification of exposure as reported in the Registry guidelines. Descriptive analysis by jobs highlights the total number of subjects for each single job and certain exposure, in descending order, insulator, plumbing, carpenter, mechanic, bricklayer, electrician, machine operator, plasterer, building contractor, painter and labourer. RESULTS: The cases grow for plumbing in the incidence periods 1993-2018, while, as expected, it decreases for insulator. Within each period considered the most numerous cases are always among bricklayers and labourers, these data confirm the prevalence of non-specialised "interchangeable" jobs in Italian construction sector in the past. CONCLUSIONS: Despite the 1992 ban, the construction sector still presents an occupational health prevention challenge, circumstances of exposure to asbestos may still occur due to incomplete compliance with prevention and protection measures.

Mesothelioma Risk Among Maritime Workers According to Job Title: Data From the Italian Mesothelioma Register (ReNaM).

The study describes the 466 cases of malignant mesotheliomas (MM) collected by the National Mesothelioma Register (ReNaM) in Italy in the period 1993-2018 relating to subjects with exclusive asbestos exposure in merchant or military navy. The cases among maritime workers represent 1.8% of the total cases with defined exposure registred in the ReNaM, of which 212 cases (45.4%) among merchant maritime workers and 254 cases (54.5%) among navy. The distribution by site of mesothelioma showed 453 (97.2%) MM cases of the pleura, 11 (2.3%) of the peritoneum and 2 (0.4%) of the tunica vaginalis of the testis. With regard to occupational exposure, it was classified as certain in 318 (68.2%) cases, probable in 69 (14.8%) cases and possible in 79 (16.9%) cases. Among the 23 classified jobs, the highest percentages of certain exposures are among naval engineers, motor mechanics, machine captains and sailors. Machine crew accounted for 49.3% of the cases, deck crew for 27.6%. All cases began exposure on board between 1926 and 1988. Seamen were exposed to asbestos while at sea by virtue of living onboard ships and from continual release of asbestos fibers due to the motion of a vessel. Epidemiological surveillance through the ReNaM has allowed us to verify among cases in the maritime, navy and merchant marine sectors, that in the past, subjects were exposed regardless of the ship's department where have provided service therefore all these cases must be considered as occupational diseases.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Setting-specific Transmission Rates: A Systematic Review and Meta-analysis.

BACKGROUND: Understanding the drivers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission is crucial for control policies, but evidence of transmission rates in different settings remains limited. METHODS: We conducted a systematic review to estimate secondary attack rates (SARs) and observed reproduction numbers (Robs) in different settings exploring differences by age, symptom status, and duration of exposure. To account for additional study heterogeneity, we employed a beta-binomial model to pool SARs across studies and a negative-binomial model to estimate Robs. RESULTS: Households showed the highest transmission rates, with a pooled SAR of 21.1% (95% confidence interval [CI]:17.4-24.8). SARs were significantly higher where the duration of household exposure exceeded 5 days compared with exposure of ≤5 days. SARs related to contacts at social events with family and friends were higher than those for low-risk casual contacts (5.9% vs 1.2%). Estimates of SARs and Robs for asymptomatic index cases were approximately one-seventh, and for presymptomatic two-thirds of those for symptomatic index cases. We found some evidence for reduced transmission potential both from and to individuals younger than 20 years of age in the household context, which is more limited when examining all settings. CONCLUSIONS: Our results suggest that exposure in settings with familiar contacts increases SARS-CoV-2 transmission potential. Additionally, the differences observed in transmissibility by index case symptom status and duration of exposure have important implications for control strategies, such as contact tracing, testing, and rapid isolation of cases. There were limited data to explore transmission patterns in workplaces, schools, and care homes, highlighting the need for further research in such settings.

Large-scale IgM and IgG SARS-CoV-2 serological screening among healthcare workers with a low infection prevalence based on nasopharyngeal swab tests in an Italian university hospital: Perspectives for public health.

BACKGROUND: Healthcare workers (HCWs) are highly exposed to SARS-CoV-2 infection given their specific tasks. The IgG-IgM serological assay has demonstrated good accuracy in early detection in symptomatic patients, but its role in the diagnosis of asymptomatic patients is uncertain. The aim of our study was to assess IgM and IgG prevalence in sera in a large cohort of HCWs previously subjected to Nasopharyngeal swab test (NST) after accurate risk assessment due to positive COVID-19 patient exposure during an observation period of 90 days. METHODS: 2407 asymptomatic HCWs that had close contact with COVID-19 patients in the period between April 8th and June 7th were screened with NST based on the RT-PCR method. In parallel, they underwent large-scale chemiluminescence immunoassays involving IgM-IgG serological screening to determine actual viral spread in the same cohort. RESULTS: During the 90-day observation period, 18 workers (0.75%) resulted positive for SARS-CoV-2 infection at the NST, whereas the positivity rates for IgM and IgG were 11.51% and 2.37%, respectively (277 workers). Despite high specificity, serological tests were inadequate for detecting SARS-CoV-2 infection in patients with previous positive NST results (IgM and IgG sensitivities of 27.78% and 50.00%, respectively). CONCLUSIONS: These findings indicate a widespread low viral load of SARS-CoV-2 among hospital workers. However, serological screening showed very low sensitivity with respect to NST in identifying infected workers, and negative IgG and IgM results should not exclude the diagnosis of COVID-19. IgG-IgM chemiluminescence immunoassays could increase the diagnosis of COVID-19 only in association with NST, and this association is considered helpful for decision-making regarding returning to work.

Role and Tasks of the Occupational Physician during the COVID-19 Pandemic.

Background and Objectives: The first clusters of SARS-CoV-2 infection were identified in an occupational setting, and to date, a significant portion of the cases may result from occupational exposure; thus, COVID-19 should also be considered a new occupational risk that both directly and indirectly impacts the health of workers. Given the significance of occupational-exposure-related infections and deaths, this study aims to assess the roles and tasks of occupational physicians (OPs) in countering the spread of the infection. Indeed, despite the OP's centrality in risk management in the workplace, its activity in the current epidemic context has rarely been mentioned. Materials and Methods: Three different databases (PubMed, Google Scholar, and Embase) were questioned using the main keywords "COVID-19" and "SARS-CoV-2" that were crossed, according to different needs, with the terms "occupational medicine", "occupational physician", "workplace", and "risk assessment" using, when possible, the MeSH database research. Additionally, a systematic research of the regulatory changes of workplaces health surveillance was performed on reference sites of international, European, and Italian authorities. Results: Fundamental tasks and duties of OPs in the current COVID-19 outbreak are highlighted by examining their clinical activity and technical action. A risk assessment and management workflow is proposed, and medico-legal implications in case of infection at work are also discussed in the light of recent regulatory changes that clearly attribute to OPs an important role in safeguarding public health. Conclusion: The proposed approach can provide new instruments to contrast the spread of the infection as part of a comprehensive system response to the current pandemic, for which OPs are called to assume full responsibility.

Asbestos exposure and malignant mesothelioma of the tunica vaginalis testis: a systematic review and the experience of the Apulia (southern Italy) mesothelioma register.

BACKGROUND: Malignant mesothelioma of the tunica vaginalis testis (MMTVT) is a rare disease with a poor prognosis. The diagnosis and management of these lesions are often difficult for pathologists, surgeons, oncologists and occupational physicians. A preoperative diagnosis of malignancy is rarely made, and there is no established effective therapy except orchidectomy. METHODS: A systematic literature review was conducted among the articles published in the English literature on primary MMTVT. Moreover four cases from the Apulia mesothelioma register are reported here. RESULTS: Two hundred eighty-nine cases of MMTVT have been reported from 1943 to 2018. Overall asbestos exposure has been investigated only for 58% of all cases reported in this review, while in 41.8% this data are not available. Noteworthy is the fact that in many reports there is not an anamnestic reconstruction of any asbestos exposure. A history of direct occupational, environmental or familial asbestos exposure is found in 27.6% of the cases. The four cases from the Apulia mesothelioma register are all with ascertained occupational exposure to asbestos. CONCLUSIONS: The true incidence of asbestos exposure in MMTVT is underestimated because of insufficient information reported in older literature. To establish a broad consensus on the causal relationship between asbestos and MMTVT in the scientific community its necessary to analyze the same variables in the epidemiological studies. In general it should be recommended that a positive history of exposure to asbestos or to asbestos-containing materials are at risk for the development of a MMTVT and should be monitored.

Occupational exposure to fluorescent light in a pathologist with myopic complications and asthenopia onset. / Esposizione professionale alla luce fluorescente in una patologa con complicanze miopiche ed insorgenza di sintomi astenopici.

BACKGROUND: Pathologic myopia is often associated with many complications, e.g. retinopathy, vitreous detachment and glaucoma. To date, occupational exposure of workers suffering from myopic co-morbidities to fluorescence light is not clearly linked to a worsening of retinal damage and eye symptoms. CASE REPORT: A 56-year-old pathologist, suffering from myopic retinopathy and other ocular comorbidities, asked for medical examination due to worsening vision and burning eyes, after occupational exposure to fluorescence microscope. Eye examination performed by an ophthalmologist detected a severe chorio-retinal atrophy in peri-papillar region and scotopic-photopic reduced voltages at electroretinogram. Moreover, a workplace inspection noted high light intensity from power source (9600 lux). Considering severity of the retinopathy, frequency of the ocular symptoms and steady occupational exposure both to low-intensity fluorescent light and high intensity light, we decided to declare the worker only fit for specific tasks which do not include the use of a fluorescence microscope. Almost six months later, the worker was recalled for a new examination and she reported the absence of the ocular discomfort that had led her to request the previous examination. CONCLUSION: In this unconventional case, we considered appropriated to use great caution, to avoid ocular fatigue and prevent possible retinal damage in the worker.

Non-occupational exposure to heavy metals of the residents of an industrial area and biomonitoring.

In areas at high environmental risk, a major issue is the assessment of the exposure of the general population to industrial pollutants. To date, few studies have investigated exposure to heavy metals in a population residing in a high risk environmental area. The aim of this study is to evaluate the exposure to heavy metals in the industrial area of Taranto, Southern Italy, through biological monitoring techniques. We measured the levels of inorganic arsenic and methylated metabolites, lead, cadmium, chromium, and manganese in the urine samples of 279 subjects residing in Taranto and neighboring areas. After obtaining informed consent from each participant, qualified health staff administered a standardized structured questionnaire investigating lifestyle habits and assessing any confounding factors. The biological monitoring data showed high urinary concentrations of nearly all of the heavy metals investigated. These findings could be related to the presence of industrial plants and is sufficient to warrant the expectation that local and national institutions should be required to adopt preventive measures to reduce the environmental exposure of the general population to heavy metals.

Increasing vaccination coverage among healthcare workers: Active call and mandatory laws. Data from a large general hospital in Southern Italy.

Influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are respiratory pathogens which significantly impact healthcare systems. Seasonal vaccination is recommended for all healthcare workers (HCWs) to reduce the risk for both operators and patients. Puglia, a region in Southern Italy, has been enforcing since 2018 a law mandating influenza vaccination in healthcare workers. However, vaccination coverages for this category have always been suboptimal. Our study tests the effectiveness of an active recall intervention on vaccination coverage for influenza and SARS-CoV-2 in the HCWs of a large Apulian hospital (Southern Italy). During the 2023-2024 influenza vaccination season, unvaccinated HCWs of Bari's Policlinico General Hospital were contacted. The e-mail reminded them of a regional law mandating influenza vaccination to all HCWs and offered an appointment for vaccination. SARS-CoV-2 vaccination was also offered. In 2022-2023, 43.16 % of HCWs were vaccinated against influenza and 21.87 % against SARS-CoV-2. Coverage changed during the 2023-2024 season to 54.11 % and 13.58 %, respectively. A regression model showed that vaccination uptake's increase was associated with the e-mail reception and with the operator being a physician vs. non-medical personnel. On the contrary, subjects who received the e-mail did not show an increased SARS-CoV-2 vaccination uptake, which was on the contrary influenced by the worker's age, sex, job title, and area of risk. Our soft-mandate intervention was effective in increasing vaccination uptake by HCWs. Communication with a trained specialist was probably useful, and the possibility to access vaccination services with dedicated appointments increased convenience. Mandatory vaccination policies and active recall seem to synergically impact vaccination uptake.

PSYCHOLOGICAL GENERAL WELL-BEING, COGNITIVE FAILURE, AND INFLAMMATION BIOMARKERS AMONG WORKERS FOUR MONTHS AFTER A MILD/ASYMPTOMATIC SARS-CoV-2 INFECTION.

OBJECTIVE: To investigate the relationship between cognitive complaints, systemic inflammatory biomarkers and psychological general well-being (PGWB) after mild/asymptomatic SARS-CoV-2 infection, according to the presence of long COVID and work tasks. METHODS: University employees and metal workers were recruited in a cross-sectional study four months after SARS-CoV-2 infection to assess cognitive impairment, individual PGWB index, inflammatory biomarkers, namely platelet-lymphocyte, neutrophil-lymphocyte and lymphocyte-monocyte ratios, and the presence of long COVID symptoms. RESULTS: A significant increase in the levels of inflammatory biomarkers was observed in subjects with long COVID. Furthermore, the PGWB index was influenced by long COVID symptoms and subjective cognitive and depressive symptoms, but not by work activity. CONCLUSIONS: In occupational settings, it is crucial to detect the presence of long COVID symptoms and systemic inflammation early, as they may be associated with lower PGWB.

Clinical investigation of former workers exposed to asbestos: the health surveillance experience of an Italian University Hospital.

Background: The need for health surveillance of former workers exposed to asbestos was provided by law in Italy after the asbestos ban in 1992. Objectives: We describe the results of the health surveillance of former workers exposed to asbestos, conducted over 27 years, from 1994 to 2020, at the Operative Unit of Occupational Medicine of the University Hospital of Bari. Materials and methods: We adopted the health surveillance protocol, which was validated at the national level in 2018. Results: A total of 1,405 former workers exposed to asbestos were examined. We proceeded with diagnosing pathologies in 339 cases (24% of the cohort subjected to surveillance), with diagnoses of some cases involving multiple pathologies. Specifically, pleural plaques were diagnosed in 49.2% of the 339 cases, asbestosis in 35.9%, malignant pleural mesothelioma (MPM) in 20.3%, mesothelioma of the vaginal tunic of the testis (MTVT) in 9.1%, lung cancer in 5.8%, and laryngeal cancer in 0.8%. Conclusion: Despite the 1992 asbestos ban, asbestos-related diseases remain a serious public health issue. It is important to establish criteria that ensure the health surveillance of formerly exposed workers minimizes costs, reduces the number of invasive examinations, and optimizes achievable results.

Indoor Radon Concentration Levels in Healthcare Settings: The Results of an Environmental Monitoring in a Large Italian University Hospital.

The aim of the study is to determine the radon concentrations in the University Hospital of Bari, Apulia Region, Southern Italy. The monitoring took place from 2017 to 2018 for a total of 402 days and included 3492 premises. Radon environmental sampling was performed with passive dosimeters of the CR-39 type. The highest mean concentration was found in basement rooms (118.9 Bq/m3), followed by ground-floor rooms (88.2 Bq/m3), first-floor rooms (78.1 Bq/m3), second-floor rooms (66.7 Bq/m3), and third-floor rooms (68.9 Bq/m3). An average radon concentration lower than the WHO recommended level of 100 Bq/m3 was detected in 73.5% of monitored environments, while only 0.9% exceeded the reference level of 300 Bq/m3 set by the national law (Legislative Decree 101/2020). The frequency of environments in which radon concentrations exceed 300 Bq/m3 is significantly higher in the basement (p-value < 0.001). As for a previous preliminary investigation in the same hospital conducted on a much smaller number of premises (n = 401), most of the monitored environments had radon concentrations lower than the reference levels set by the new national law, and the risk to the healthcare workers' health derived from occupational exposure to radon could be considered acceptable.

SARS-CoV-2 Breakthrough Infections in Health Care Workers: An Italian Retrospective Cohort Study on Characteristics, Clinical Course and Outcomes.

BACKGROUND: The aim of this study was to determine the characteristics, clinical course and outcomes of COVID-19 breakthrough infections (BIs) among healthcare workers (HCWs) of an Italian University Hospital. METHODS: A retrospective observational study was conducted on 6111 HCWs, from January 2021 to February 2022. The study population was offered the full vaccination with BNT162b2 mRNA COVID-19 vaccine. To allow return to work after BI, the protocol required one negative nasopharyngeal RT-PCR swab followed by a medical examination to assess the HCW's health status. Laboratory tests, instrumental tests and specialist evaluations were carried out if necessary. RESULTS: The cases of BIs observed numbered 582 (9.7%). The frequency of BIs was significantly higher in females than in males (67% vs. 33%; p = 0.03), and in nurses than in all other professional categories (p = 0.001). A total of 88% of the HCWs affected by BI were still symptomatic after the negative swab. None of the instrumental tests carried out showed any new findings of pathological significance. All cases showed progressive disappearance of symptoms, such that no cases of long COVID and no hospitalization or deaths were recorded. CONCLUSIONS: Our results confirm that SARS-CoV-2 infections occur even after a full vaccination course; however, the clinical course is favorable and severe outcomes are reduced.

Infection Control among Healthcare Workers and Management of a Scabies Outbreak in a Large Italian University Hospital.

This retrospective observational study describes the results of an ad-hoc designated prevention protocol aimed at containing the spread of the scabies infestation among healthcare workers (HCWs) of a large University Hospital in Italy. The outbreak started on October 2022 and a preventive protocol was set up thanks to a multidisciplinary approach. HCWs at high scabies risk were defined as subjects working in Operative Units with a scabies prevalence higher than 2%, close contacts of a confirmed case of scabies, or HCWs with signs and symptoms of the disease. All cases at high scabies risk underwent a dermatological examination, and the infested HCWs were suspended from work until definitive healing. Mass drug administration was established for all HCWs working in Operative Units with a scabies prevalence higher than 2%. Until March 2023, out of 183 screening dermatological examinations, 21 (11.5%) were diagnostic for scabies. Between 11 October 2022 (date of the first diagnosed scabies case) and 6 March 2023 (the end of incubation period related to the last case detected), the frequency of scabies was 0.35% (21 scabies cases/6000 HCWs). The duration of the outbreak in our hospital was 14.7 weeks. Statistical analysis shows a significant association between scabies and being a nurse and having an allergy to dust mites. We obtained a low frequency of scabies infection, limiting the duration of the outbreak and the related economic burden.

SARS-CoV-2 Infections, Re-Infections and Clinical Characteristics: A Two-Year Retrospective Study in a Large University Hospital Cohort of Vaccinated Healthcare Workers.

At the University Hospital of Bari, during the first year after the start of the mandatory vaccination campaign with BNT162b2 mRNA COVID-19 vaccine, the preliminary results of an observational study showed a significant prevalence of SARS-CoV-2 breakthrough infections (BIs) among healthcare workers (HCWs), but no hospitalization or deaths. In the present study, we extended the observation period (January 2021-January 2023) with the aim of determining the incidence, characteristics and clinical course of SARS-CoV-2 BIs among 6213 HCWs. All HCWs were regularly monitored and screened. To allow return to work after BI, the protocol required one negative nasopharyngeal swab test followed by a medical examination certifying complete clinical recovery. We observed an overall incidence rate of SARS-CoV-2 BIs of 20.2%. Females were most affected, especially in the nurse group compared with doctors and other HCWs (p < 0.0001). Cardiovascular diseases were the most frequent comorbidity (n = 140; 11.4%). The source of infection was non-occupational in 52.4% of cases. Most cases (96.9%) showed minor symptoms and only two cases of hospitalization (one in intensive care unit), 13 cases of re-infection and no deaths were recorded. Our results confirm that SARS-CoV-2 infection can break vaccination protection but the clinical course is favorable.

Determinants of Anti-S Immune Response at 12 Months after SARS-CoV-2 Vaccination in a Multicentric European Cohort of Healthcare Workers-ORCHESTRA Project.

BACKGROUND: The effectiveness of the immunity provided by SARS-CoV-2 vaccines is an important public health issue. We analyzed the determinants of 12-month serology in a multicenter European cohort of vaccinated healthcare workers (HCW). METHODS: We analyzed the sociodemographic characteristics and levels of anti-SARS-CoV-2 spike antibodies (IgG) in a cohort of 16,101 vaccinated HCW from eleven centers in Germany, Italy, Romania, Slovakia and Spain. Considering the skewness of the distribution, the serological levels were transformed using log or cubic standardization and normalized by dividing them by center-specific standard errors. We fitted center-specific multivariate regression models to estimate the cohort-specific relative risks (RR) of an increase of one standard deviation of log or cubic antibody level and the corresponding 95% confidence interval (CI) for different factors and combined them in random-effects meta-analyses. RESULTS: We included 16,101 HCW in the analysis. A high antibody level was positively associated with age (RR = 1.04, 95% CI = 1.00-1.08 per 10-year increase), previous infection (RR = 1.78, 95% CI 1.29-2.45) and use of Spikevax [Moderna] with combinations compared to Comirnaty [BioNTech/Pfizer] (RR = 1.07, 95% CI 0.97-1.19) and was negatively associated with the time since last vaccine (RR = 0.94, 95% CI 0.91-0.98 per 30-day increase). CONCLUSIONS: These results provide insight about vaccine-induced immunity to SARS-CoV-2, an analysis of its determinants and quantification of the antibody decay trend with time since vaccination.

Vaccination Offer during the Occupational Health Surveillance Program for Healthcare Workers and Suitability to Work: An Italian Retrospective Cohort Study.

The active immunization of health care workers (HCWs) is a crucial measure to avoid nosocomial infection; nevertheless, vaccine coverage (VC) among health personnel in Italy is unsatisfactory. To improve VC in the healthcare set, the Hygiene and Occupational Medicine departments of Bari Policlinico General University Hospital applied a specific program. The operative procedure demands that in the context of the occupational medical examination, all workers are evaluated for susceptibility to vaccine-preventable diseases (VDPs), with immunization prophylaxis offered to those determined to be susceptible. This study analyzed data from workers who attended the biological risk assessment protocol from December 2017 to October 2021 (n = 1477), who were evaluated for the immune status for measles, mumps, rubella, and varicella. Among the enrolled subjects, non-protective antibody titers were higher for measles and mumps (13%), followed by rubella (11%) and varicella (8%). Appropriate vaccinations were offered to all susceptible HCWs, and HCWs were re-tested one month after immunization. The seroconversion rate after the administration of one or more booster dose(s) was over 80%. Overall, 2.5% of the subjects refused the offered vaccine(s); the main determinant of immunization compliance was younger age (aOR = 0.86; 95%CI = 0.80-0.92). Especially during the COVID-19 pandemic, VPDs may still present a hazard in nosocomial environment. Our experience suggests that, despite hospital procedures and dedicated human assets, satisfactory VC cannot be reached without the provision of federal regulations. Nevertheless, public health policymakers have to improve the promotion of vaccine prophylaxis and education to reach higher VC.

Comparison of Three Different Waves in Healthcare Workers during the COVID-19 Pandemic: A Retrospective Observational Study in an Italian University Hospital.

Background: SARS-CoV-2 has infected many healthcare workers and (HCWs) worldwide. The aim of this study was to determine, analyze, and compare the frequency and characteristics of COVID-19 cases among HCWs of the University Hospital of Bari. Methods: A retrospective observational study was conducted after preventive protocol implementation. The SARS-CoV-2 infection frequency was determined by real-time reverse transcription-polymerase chain reaction on nasopharyngeal samples. Results: Overall, 519 HCWs (9%) tested positive among a total of 6030 HCWs during the three waves. The highest frequency of COVID-19 cases (n = 326; 63%) was observed during the 2nd wave, from September 2020 to December 2020, and the lowest (n = 34; 7%) was observed during the 1st wave, from March 2020 to August 2020 (p < 0.001). Working in a designated COVID-19 department was not a risk factor for infection. Conclusions: The correct use of personal protective equipment and the early identification of symptomatic workers are still essential factors to avoid nosocomial clusters, even in this current phase of vaccine availability.