Infectious Disease Reports

Background: Sexual assault victims involving penetration are at risk of contracting human immunodeficiency virus (HIV). Post-exposure prophylaxis (PEP) can effectively prevent HIV infection if initiated promptly within 72 h following exposure and adhered to for 28 days. Nonetheless, therapeutic adherence amongst sexual assault victims is low. Victim-centered care, provided by specially trained forensic nurses and midwives, may increase adherence. Methods: We conducted a retrospective case–control study to evaluate the impact of sexual assault center (SAC)—centered care on adherence to PEP compared to care received in the emergency department (ED). Data from January 2011 to February 2022 were reviewed. Multivariable logistic regression analysis was employed to determine the association between centralized specific care for sexual assault victims and completion of the 28-day PEP regimen. The secondary outcome assessed was provision of psychological support within 5 days following the assault. Results: We analyzed 856 patients of whom 403 (47.1%) received care at a specialized center for sexual assault victims. Attendance at the SAC, relative to the ED, was not associated with greater probability of PEP completion both in the unadjusted (52% vs. 50.6%; odds ratio [OR]: 1.06, 95% CI: 0.81 to 1.39; p = 0.666) and adjusted (OR: 0.81, 95%CI 0.58–1.11; p = 0.193) analysis. The care provided at the SAC was associated with improved early (42.7% vs. 21.5%; p < 0.001) and delayed (67.3% vs. 33.7%; p < 0.001) psychological support. Conclusions: SAC-centered care is not associated with an increase in PEP completion rates in sexual assault victims beyond the increase associated with improved access to early and delayed psychological support. Other measures to improve PEP completion rates should be developed. What is already known on this topic—Completion rates for HIV post-exposure prophylaxis (PEP) among victims of sexual assault are low. Specialized sexual assault centers, which provide comprehensive care and are distinct from emergency departments, have been suggested as a potential means of improving treatment adherence and completion rates. However, their actual impact on treatment completion remains unclear. What this study adds—This study found that HIV PEP completion rates in sexual assault victims were not significantly improved by centralized care in a specialized sexual assault center when compared to care initiated in the emergency department and continued within a sexually transmitted infection clinic. However, linkage to urgent psychological and psychiatric care was better in the specialized sexual assault center. How this study might affect research, practice or policy—Healthcare providers in sexual assault centers should be more aware of their critical role in promoting PEP adherence and improving completion rates. Policymakers should ensure that measures aimed at improving HIV PEP outcomes are implemented at all points of patient contact in these centers. Further research is needed to assess the cost-effectiveness of specialized sexual assault centers. Full article

Background/Objectives: Antibiotic resistance is a significant and escalating challenge that limits available therapeutic options. This issue is further exacerbated by the decreasing number of new antibiotics being developed. Our study aims to describe the epidemiology and pattern of antibiotic resistance in Gram-negative infections isolated from a cohort of hospitalized patients and to analyze the distribution of infections within the hospital setting. Methods: A retrospective study was conducted on all patients admitted to Vito Fazzi Hospital in Lecce, Italy, who required an infectious disease consultation due to the isolation of Gram-negative bacteria from 1 January 2018 to 31 December 2022. Results: During the study period, 402 isolates obtained from 382 patients (240 men and 142 women) with infections caused by Gram-negative bacteria were identified. Among these isolated, 226 exhibited multidrug resistance, defined as resistance to at least one antimicrobial agent from three or more different classes. In 2018, the percentage of multidrug-resistant isolates peaked at 87.6%, before decreasing to the lowest level (66.2%) in 2021. Overall, of the 402 isolates, 154 (38.3%) displayed resistance to carbapenems, while 73 (18.1%) were resistant to extended-spectrum beta-lactamases (ESBLs). Among the resistant microorganisms, Klebsiella pneumoniae showed the highest resistance to carbapenems, accounting for 85.2% of all resistant strains. Escherichia coli exhibited the greatest resistance to ESBLs, with a rate of 86.7%. Among carbapenem-resistant K. pneumoniae isolates, the following resistance rates were observed: KPC-1 at 98.2%, IMP-1 at 0.9%, VIM-1 at 0.9%, and NDM-1 at 0.9%. Conclusions: Patients with infections caused by multidrug-resistant bacteria have limited treatment options and are therefore at an increased risk of death, complications, and longer hospital stays. Rapid diagnostic techniques and antimicrobial stewardship programs—especially for ESBLs and carbapenemases—can significantly shorten the time needed to identify the infection and initiate appropriate antimicrobial therapy compared to traditional methods. Additionally, enhancing surveillance of antimicrobial resistance within populations is crucial to address this emerging public health challenge. Full article

Background: Although COVID-19 vaccination has been effective in reducing severe illness and mortality, its differential clinical behavior in vaccinated and unvaccinated individuals during the early stages of the pandemic—especially in settings with partial coverage and real-world conditions—remains insufficiently characterized. Objective: To assess differences in clinical presentation, comorbidity prevalence, hospitalization, and mortality between vaccinated and unvaccinated patients diagnosed with SARS-CoV-2 during the early phase of the pandemic. Methods: An analytical cross-sectional study was conducted using 4625 electronic medical records of patients diagnosed with COVID-19 in Guerrero, Mexico, between 1 January and 31 December 2021. Variables included vaccination status, age, sex, comorbidities, symptom severity, clinical outcomes, and mortality. Statistical analyses involved chi-square tests, logistic regression for hospitalization probability, and Cox proportional hazards models for mortality risk. Results: Of the patients analyzed, 31.45% had received at least one vaccine dose. Fever, headache, cough, and anosmia were more frequent among vaccinated individuals (p < 0.001). Prostration and chest pain were strongly associated with hospitalization in both groups. In unvaccinated patients, smoking (OR = 4.75), obesity (OR = 3.85), and hypertension (OR = 2.94) increased hospitalization risk. Among vaccinated patients, diabetes mellitus (OR = 3.62) and hypertension (OR = 2.88) were key predictors. Vaccination was significantly associated with lower odds of hospitalization (OR = 0.38; 95% CI: 0.26–0.55) and reduced mortality risk (HR = 0.24; 95% CI: 0.08–0.71). Conclusions: Vaccination status was a significant protective factor for both hospitalization and mortality; however, clinical symptoms and comorbidity-related risks varied, highlighting the need for individualized patient management strategies. Full article

Background: Hepatitis C virus (HCV) remains a significant public health concern in Thailand, with genotype-specific, drug-dependent variations influencing treatment response and disease progression. Despite the availability of pan-genotypic direct-acting antivirals (DAAs), genotype surveillance remains essential for optimizing national elimination strategies. This study thus aims to characterize the molecular distribution of HCV genotypes in northern Thailand. Methods: We conducted a retrospective molecular epidemiological study on 1737 HCV-infected patients who attended the Clinical Microbiology Service Unit (CMSU) Laboratory, Faculty of Associated Medical Sciences, Chiang Mai University between April 2016 and June 2024. HCV genotyping was performed using Sanger sequencing and reverse hybridization line probe assay (LiPA). Results: Genotype 3 was the most prevalent (36.6%), followed by genotype 1 (35.8%) and genotype 6 (27.2%). Subtype 3a (27.2%) predominated, along with 1a (22.1%), 1b (12.6%), and genotype 6 subtypes including 6c to 6l (13.5%) and 6n (6.6%). Males had a higher prevalence of genotype 1, while genotype 3 was more common among females. Temporal analysis revealed a relative increase in genotype 6 prevalence since 2021. Genotype 6 also exhibited significantly higher median viral loads compared to genotypes 1 and 3 (p < 0.0001). Conclusions: This study provides updated evidence on the shifting distribution of HCV genotypes in northern Thailand, particularly the increasing prevalence of genotype 6. These findings underscore the importance of continued molecular surveillance to guide genotype-specific treatment strategies and support Thailand’s 2030 HCV elimination goals. Full article

Impetigo is a highly contagious bacterial skin infection characterized by blistering and erosions that can lead to significant discomfort and complications. The standard treatment includes topical or systemic antibiotics, but severe cases may require advanced wound management strategies. Polylactic acid (PLA)-based membranes have demonstrated effectiveness in enhancing wound healing, modulating inflammation, and reducing pain. Clinical case: We present three cases of bullous impetigo with extensive erosions, managed using PLA membranes as an adjunct to systemic antibiotics. A significant improvement was shown after 7 days of treatment of a single application, and complete resolution was achieved after 30 days. Notably, pain was resolved within 48–72 h, highlighting the analgesic and protective properties of the membrane. Conclusions: These findings suggest that PLA membranes provide a viable adjunct to antibiotic therapy in bullous impetigo, accelerating healing, reducing discomfort, and improving long-term skin outcomes. Given the increasing concern over antibiotic resistance and the limitations of standard wound care, bioresorbable synthetic membranes represent a promising alternative in dermatological wound management. Full article

Background: This commentary analyzes demographic, clinical, and occupational characteristics associated with Ebola virus disease (EVD) outcomes during the 2018–2020 outbreak in the Democratic Republic of Congo (DRC). Methods: A total of 3477 EVD cases were included. Descriptive statistics and univariate and multivariate Cox regression analyses were performed to evaluate associations between clinical outcomes and patient characteristics. Comorbidity estimates and healthcare worker (HCW) occupational exposure data were incorporated based on the literature. Results: The median age was 26.5 years (SD = 16.1), with the majority (59.7%) aged 20–59. Males represented 51.3% of the cohort. Most patients (81.8%) worked in occupations that were not disease-exposing. Overall, 450 patients (12.9%) died. Although comorbidities initially appeared predictive of mortality (unadjusted HR: 3.05; 95% CI: 2.41–3.87), their effect was not statistically significant after adjustment (adjusted HR: 1.17; 95% CI: 0.87–1.59; p = 0.301). The strongest predictor of death was clinical status at admission: patients classified as “very sick” had an alarmingly high adjusted hazard ratio (HR) of 236.26 (95% CI: 33.18–1682.21; p < 0.001). Non-disease-exposing occupations were also associated with increased mortality (adjusted HR: 1.75; 95% CI: 1.33–2.31; p < 0.001). Conclusions: Despite improvements in outbreak response, mortality remains disproportionately high among patients presenting in critical condition and those outside the health sector. These findings underscore the importance of early detection strategies and enhanced protection for all occupational groups during EVD outbreaks. Full article

Background: Dental professionals were thought to have the most significant risk of coronavirus infection during the pandemic. Since the first Coronavirus Disease 2019 (COVID-19) patient was detected in Japan in January 2020, Japan has faced several waves of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections. However, no cluster of SARS-CoV-2 infections associated with dental procedures has been reported in Japan. In this study, we aimed to investigate the actual status of SARS-CoV-2 infection during the pandemic through antibody testing for dental professionals. We further investigated saliva and oral management-related aerosol to estimate the risk of virus transmission during dental procedures. Methods: SARS-CoV-2 antibody titer in the blood of dental professionals and their families was determined during the pre-vaccinated period of the SARS-CoV-2 wave to see the history of infection in Japan. Viral loads in saliva and in the aerosol generated during the oral management of COVID-19 patients were detected by RT-qPCR. Results: The antibody testing of dental healthcare providers during the early phases of the pandemic in Japan revealed low antibody positivity, which supported the low incidence of infection clusters among dental clinics. The aerosol generated during dental procedures may contain trace levels of SARS-CoV-2, indicating the risk of transmission through dental procedures is limited. Therefore, SARS-CoV-2 did not spread through dental clinics. Conclusions: Very few SARS-CoV-2 infections were observed in dental professionals who took appropriate infection control measures in the early period of the pandemic. Performing dental procedures using standard precautions seems to be sufficient to prevent SARS-CoV-2 infections. Full article

Background/Objectives: Long COVID is a condition that was initially recognized by social support groups, and later by the scientific and medical communities. It affects COVID-19 survivors at various levels of severity, including young people, children and non-hospitalized people. Although the exact definition is unclear, the most common symptoms are fatigue and shortness of breath, which persist for months. Other symptoms include cognitive impairment, pain, palpitations, and gastrointestinal and heart problems. This study evaluated the reliability and validity of a questionnaire designed to examine the development and effects of long COVID. Methods: A questionnaire, composed of three sections, with a total of 24 items, was administered to subjects who had recovered from the COVID-19 disease in Italy. Data were collected from February to April 2025, and a statistical analysis was performed using R^® statistical software for Windows, version 4.3.3. Cronbach’s alpha was tested to check internal consistency. The questionnaire was completed voluntarily and anonymously by 250 individuals who had recovered from the SARS-CoV-2 infection. The questionnaire was self-administered and had open and structured questions. Results: The highest value of Cronbach’s alpha was found on 18 items (alpha = 0.97), which means that the questionnaire has satisfactory internal validity. Conclusions: This study highlights and confirms the continuity of symptoms manifested during the acute phase of the SARS-CoV-2 infection in the post-COVID-19 phase and the significant impact of these symptoms on daily life activities. Given its excellent reliability properties and high internal consistency, the instrument is recommended for future longitudinal studies and with large cohorts in order to carry out valid and replicable measurements of COVID-19 symptomatology. Full article

Introduction: Over the past few decades, the rising incidence of herpes zoster (HZ) rates appears to have been a global phenomenon. In Türkiye, there is a lack of comprehensive studies addressing the HZ burden of disease, risk factors, and clinical characteristics. The aim of the VARICOMP-Adult study was to evaluate the clinical and demographic findings of adult patients with HZ. Patients and Methods: We enrolled the medical records of 1955 patients, 1010 females and 945 males, aged between 18 and 97 years between 2009 and 2014. Results: The presence of underlying conditions was present in 35.5% of patients and 345 patients (17.6%) had immunosuppression; 18.0% of patients required hospitalization. The mean age, the presence of underlying conditions, and immunosuppression in hospitalized cases with HZ were higher than those in outpatients. Logistic regression analysis revealed the following risk factors for hospitalization: age, immunosuppression, hypertension, hematological disorders, transplantation, COPD, and the presence of HZ opthalmicus or disseminated disease. We observed seven HZ cases with mortality aged between 58 and 80 years, and all cases had an underlying condition; 9.9% of the entire population reported postherpetic neuralgia (PHN), and age and no previous antiviral medications were the risk factors for PHN. Conclusions: This is the largest nationwide study of adult patients with HZ. Effective healthcare interventions such as antiviral therapy and immunization could prove beneficial in combating disease and treating HZ complications, especially in the high-risk population and individuals of older ages. Full article

Background: Rising rates of opioid use disorder (OUD), usually via injection, has resulted in younger patients being diagnosed with infective endocarditis (IE), with unique treatment challenges. Methods: This retrospective ecological study analyzed hospital discharge and home health records from 2016 to 2022 in South Carolina (SC). Cases of IE with concurrent coding for OUD were identified. Differences in patient demographics, hospital characteristics, length of care days, and charges by OUD status were determined using chi-square or t-tests. IE hospitalization rates by OUD status, year, and age group were calculated, and linear regression was used to determine differences by year. Results: There were 8601 acute-care hospitalization records for IE from 2016 to 2022 in the SC dataset, of which 1180 (13.7%) had concurrent OUD coding. Statistically significant differences between patients with and without OUD were identified for sex, age group, race, resident rurality, average number of comorbidities, disposition status, and year (all p < 0.01). The incidence rate of IE increased from 2.5/100,000 in 2016 to 6.9/100,000 in 2022 in patients aged 36 to 49 years with OUD (p = 0.02). Patients with IE and OUD who were discharged home had significantly longer lengths of stay in acute care hospitals (32.9 vs. 15.3 days; p < 0.01) and excessive hospital charges ($308,874 vs. $188,862) compared to those without OUD. Conclusions: Major changes have occurred in the demographics of IE in SC. The increasing incidence rate of IE in younger adults with OUD coupled with prolonged stays at acute care hospitals pose challenges to the healthcare system that require creative solutions. Full article

Pulmonary arterial hypertension (PAH) is an irreversible disease characterized by vascular and systemic inflammation, ultimately leading to right ventricular failure. There is a great need for adjunctive therapies to extend survival for PAH patients. The gut microbiome influences the host immune system and is a potential novel target for PAH treatment. We review the emerging preclinical and clinical evidence which strongly suggests that there is gut dysbiosis in PAH and that alterations in the gut microbiome may either initiate or facilitate the progression of PAH by modifying systemic immune responses. We also outline approaches to modify the intestinal microbiome and delineate some practical challenges that may impact efforts to translate preclinical microbiome findings to PAH patients. Finally, we briefly describe studies that demonstrate contributions of infections to PAH pathogenesis. We hope that this review will propel further investigations into the mechanisms by which gut dysbiosis impacts PAH and/or right ventricular function, approaches to modify the gut microbiome, and the impact of infections on PAH development or progression. Full article

Background: Human Immunodeficiency Virus (HIV) infections remain a source of cardiopulmonary complications among people receiving antiretroviral therapy. Still to this day, pulmonary hypertension (PH) severely affects the prognosis in this patient population. The persistent expression of HIV proteins, even during viral suppression, has been implicated in vascular dysfunction; however, little is known about the specific effects of these proteins on the pulmonary vasculature. This study investigates the impact of Nef variants derived from HIV-positive pulmonary hypertensive and normotensive donors on pulmonary vascular cells in vitro. Methods: We utilized well-characterized Nef molecular constructs to examine their effects on cell adhesion molecule gene expression (ICAM1, VCAM1, and SELE), pro-apoptotic gene expression (BAX, BAK), and vasoconstrictive endothelin-1 (EDN1) gene expression in endothelial nitric oxide synthase (eNOS) nitric oxide and the production and secretion of pro-inflammatory cytokines over 24, 48, and 72 h post-transfections with Nef variants. Results: HIV Nef variants SF2, NA7, and PH-associated Fr17 and 3236 induced a significant increase in adhesion molecule gene expression of ICAM1, VCAM1, and SELE. Pulmonary normotensive Nef 1138 decreased ICAM1 gene expression, but had increased VCAM1. PH Nef ItVR showed a consistent decrease in ICAM1 and no changes in SELE and VCAM1 expression. Further gene expression analyses of pro-apoptotic genes BAX and BAK demonstrated that Nef NA7, SF2, normotensive Nef 1138, and PH Nef Fr8, Fr9, Fr17, and 3236 variants significantly increased gene expression for apoptosis. Normotensive Nef 1138, as well as PH Nef Fr9 and ItVR, all displayed a statistically significant decrease in BAX expression. The expression of EDN1 had a statistically significant increase in samples treated with Nef NA7, SF2, normotensive Nef 2044 and PH Nef 3236, Fr17, and Fr8. Notably, PH-associated Nef variants sustained pro-inflammatory cytokine production, including IL-2, IL-4, and TNFα, while anti-inflammatory cytokine levels remained insufficient. Furthermore, eNOS was transiently upregulated by all Nef variants except for normotensive Nef 2044. Conclusions: The distinct effects of Nef variants on pulmonary vascular cell biology highlight the complex interplay between Nef, host factors, and vascular pathogenesis according to the variants. Full article

Catheter-associated urinary tract infections (CAUTIs), caused by microbial colonization of catheter surfaces, are among the most common healthcare-associated infections and significantly strain healthcare systems worldwide. This review aimed to provide a comprehensive analysis of the current scientific literature and the patent landscape from 2014 to 2024 on strategies for preventing CAUTIs. A systematic search was conducted using the PRISMA method, which involved searching the Scopus database for scientific evidence and analyzing patent search results on The Lens.org platform. Co-authorship and co-occurrence analysis unveiled key contributors and emerging themes within the scientific community. Simultaneously, an in-depth inspection of patents filed elucidated top origins, applicants, and classifications. Additionally, network analysis based on keywords from papers and patents revealed the scientific scenario and the innovation trends, enriching the understanding of technological advancements. It highlights emerging technologies, key actors, and potential gaps, providing valuable insights for researchers, clinicians, and industry stakeholders, thereby contributing to overcoming barriers to treating CAUTIs. Full article

Background: Southern Brazil faced massive rains and floods in May 2024, which led to social, infrastructural, and One Health issues affecting over 478 municipalities and 2.3 million people. Exposure to floodwater increased the risk of bacterial infections, including leptospirosis. Despite the zoonotic nature of leptospiral infections, only human leptospirosis is subject to mandatory reporting, while canine cases are less closely monitored. Considering the extent of this climatic event, many emergency shelters were created for rescued dogs, highlighting the need to monitor infectious diseases to mitigate the spread of hazardous pathogens. Methods: We performed a molecular assessment of canine leptospirosis in Porto Alegre and its metropolitan region. A total of 246 dogs rescued from the flooded areas underwent molecular diagnosis targeting lipL32. In addition, positive samples were identified by sequencing of the partial secY gene. Results: A total of 9 (4%) dogs were positive for Leptospira spp. Molecular and phylogenetic analyses of secY from the positive samples determined that the circulating strains belonged to L. interrogans (n = 8)—Icterohaemorrhagiae and Pomona as the suggested serogroups—and L. kirschneri (n = 1). Conclusions: Our findings point out the challenges in diagnosing and controlling leptospirosis during severe climatic events and reinforce the need for preventive sanitary measures to mitigate the dissemination of Leptospira spp., including the adoption of a mandatory notification system for canine leptospirosis. Full article

Background: Whipple’s disease (WD) is a rare infection caused by Tropheryma whipplei. Diagnosis is challenging and requires a combination of several data sets, such as patient history, clinical and laboratory investigations, and endoscopy with histology analyses. While persistent diarrhea is a common symptom, WD can affect multiple organs. Case description: We present the case of a 66-year-old immunocompetent patient with WD and a history of Helicobacter pylori infection who developed chronic diarrhea. Colonoscopy and histopathological analysis revealed the presence of foamy macrophages with periodic acid-Schiff-positive particles. Subsequently, molecular methods confirmed the clinical WD diagnosis and metagenomic analyses further identified a co-infection with Giardia intestinalis. The patient fully recovered after 14 months of antibiotic therapy. During pharmacological treatment, clinical and laboratory follow-ups were conducted at 6 and 12 months, and microbiome profiles were also analyzed to identify the most abundant species in the samples. Conclusion: The metagenomic analyses showed the eradication of the two pathogens and a progressive restoration to a healthy/balanced status after antibiotic therapy. Full article

Background/Objectives: Enterovirus-D68 (EV-D68) and rhinoviruses are major contributors to respiratory illnesses in children, presenting a spectrum of clinical manifestations ranging from asymptomatic cases to severe lower respiratory tract infections. No specific antiviral treatments are currently approved for these viruses. Method: We conducted a comprehensive literature review of antiviral agents investigated for EV-D68 and rhinovirus infections. Results: Several antiviral candidates are under investigation, each targeting distinct stages of the viral replicative cycle. Capsid-binding agents and monoclonal antibodies prevent viral attachment by blocking receptor-virus interactions. Inhibitors of viral replication proteins disrupt polyprotein processing and replication organelle biogenesis by targeting non-structural viral proteins. Host factor inhibitors impair viral attachment, replication organelle formation, or RNA replication by interfering with critical host pathways. Conclusions: While no specific antivirals are yet approved for EV-D68 and rhinovirus infections, emerging therapeutic candidates offer potential avenues for treatment. Continued preclinical and clinical investigation will be essential to validate these approaches and expand the available options for affected patients. Full article

Background/Objectives: Nontuberculous mycobacteria (NTM) represent a heterogeneous group of pathogens with increasing global prevalence and significant geographical variation in species distribution. NTM infections, often affecting immunocompromised individuals, are difficult to diagnose due to nonspecific clinical presentations and laboratory findings. This case study presents a rare extrapulmonary NTM infection in a 73-year-old man, initially misdiagnosed as sarcoidosis, highlighting the diagnostic and therapeutic challenges posed by such infections. Methods: The patient, a pigeon fancier, presented with recurrent fever and pancytopenia. Extensive diagnostics included blood cultures, bone marrow aspiration, and histopathology. Initial cultures and serological tests remained negative. Results: Bone marrow aspiration revealed epithelioid granulomas, initially leading to the provisional diagnosis of sarcoidosis. However, after six weeks, M. genavense was isolated from mycobacterial blood cultures from bone marrow aspirant. Antimicrobial therapy with azithromycin, rifampicin, and ethambutol was initiated. Following the initiation of appropriate antimycobacterial therapy, the patient developed immune reconstitution inflammatory syndrome (IRIS), which was managed with supportive care. The patient’s condition improved, and no further febrile episodes occurred post-treatment, marking the successful conclusion of NTM therapy. Conclusions: This case underscores the diagnostic complexity of extrapulmonary NTM infections, particularly in immunocompromised patients. Misdiagnosis can delay appropriate treatment. M. genavense, though rare, should be considered in patients with a fever of unknown origin, especially with a background of immunosuppression. Prompt mycobacterial testing and tailored antibiotic therapy are crucial to improving outcomes in NTM infections. Full article

Background/Objectives: COVID-19 pandemic had a significant impact on endemic respiratory illnesses. Through behavioral changes in populations and government policy, mainly through non-pharmaceutical interventions (NPIs), Canada saw historic lows in the number of influenza A cases from 2020 through 2022. In this study, we use historical influenza A data for Canada and three provincial jurisdictions within Canada—Ontario, Quebec, and Alberta—to quantify the effects of these NPIs on influenza A. Methods: We aim to see which base parameters and derived parameters of an SIR model are most affected by NPIs. We fit a simple SIR model to historical influenza data to get average paramters for seasonal influenza. We then compare these parameters to those predicted by fitting influenza cases during the COVID-19 pandemic. Results: We find substantial differences in the effective population size and basic reproduction number during the COVID-19 pandemic. We also see the effects of fatigue and relaxation of NPIs when comparing the years 2020, 2021, and 2022. Conclusions: We find that the effective population size is the main driver of change to disease spread and discuss how these retrospective estimates can be used for future forecasting. Full article