Prevalence and risk factors for long COVID after mild disease: A cohort study with a symptomatic control group.

Background: There is limited data on the prevalence and risk factors for long COVID and few prospective studies with appropriate control groups and adequate sample sizes. We performed a prospective study to determine the prevalence and risk factors for long COVID. Methods: We recruited individuals aged ≥15 years who were clinically suspected of having an acute SARS-CoV-2 infection from September 2020 to April 2021. We collected nasopharyngeal swabs three to five days following symptom onset for analysing using reverse transcriptase polymerase chain reaction (RT-PCR). We also collected clinical and sociodemographic characteristics from both SARS-CoV-2 positive and negative participants using structured questionnaires. We followed-up the participants via telephone interview to assess early outcomes and persistent symptoms. For COVID-19 cases, 5D-3L EuroQol questionnaire was used to assess the impact of symptoms on quality of life. Results: We followed 814 participants (412 COVID-19 positive and 402 COVID-19 negative persons). Most (n = 741/814) had mild symptoms. Both groups had similar sociodemographic and clinical characteristics, except for the hospitalization rate (15.8% in the COVID-19 positive vs 1.5% in the COVID-19 negative group). One month after disease onset, 122/412 (29.6%) individuals in the COVID-19 positive (long COVID) and 24 (6%) in the COVID-19 negative group reported residual symptoms. In the long COVID group, fatigue, olfactory disorder, and myalgia were the most frequent symptoms in the acute phase. Compared to recovered individuals, older age and having more than five symptoms during the acute phase were risk factors for long COVID. Quality of life was evaluated in 102 out of 122 cases of long COVID, with 57 (55.9%) reporting an impact in at least one dimension of the European Quality of Life 5 Dimensions 3 Level (EQ-5D-3L) questionnaire. Conclusions: In this prospective study consisting predominantly of individuals with mild disease, the persistence of symptoms after an acute respiratory illness was associated with a diagnosis of COVID-19. Polysymptomatic acute disease and older age were risk factors for long COVID.

Application effect evaluation of hybrid biochemistry teaching model based on WeChat platform under the trend of COVID-19.

With WeChat platform as the carrier, we explored the effect of online and offline mixed teaching mode applied to Biochemistry teaching. One hundred and eighty-three students from the 4-year nursing major of Xinglin College of Nantong University in 2018 and 2019 were used as the observation group, using online and offline hybrid teaching methods, and 221 students majoring in 4-year nursing from Xinglin College of Nantong University in 2016 and 2017 were the control group, where the traditional classroom teaching method was adopted. The usual stage scores and final scores of the observation group were significantly higher than those of the control group (P < .01). The micro-lecture videos, animations, and periodic assessment methods of the WeChat platform under "Internet+" can greatly stimulate students' interest in learning, thereby significantly improving academic performance and autonomous learning ability.

Network Analysis of Neurobehavioral Symptom Patterns in an International Sample of Spanish-Speakers with a History of COVID-19 and Controls.

(1) Background: Psychometric network analysis provides a novel statistical approach allowing researchers to model clusters of related symptoms as a dynamic system. This study applied network analysis to investigate the patterns of somatic, cognitive, and affective neurobehavioral symptoms in an international sample of Spanish-speaking individuals with a history of COVID-19 positivity and non-COVID controls; (2) methods: the sample (n = 1093) included 650 adults from 26 countries who reported having previously tested positive for COVID-19 (COVID+) through a viral and/or antigen test (average of 147 days since diagnosis). The control group (COVID-) was comprised of 443 adults from 20 countries who had completed the survey prior to the COVID-19 pandemic; (3) results: relative to the COVID- network, the COVID+ network was very well-connected, such that each neurobehavioral symptom was positively connected to the network. The organize-to-headache and dizzy-to-balance connections in the COVID+ network were stronger than in the COVID- network. The hearing, numbness, and tense symptoms were more central to the COVID+ network with the latter connected to the sleep, fatigue, and frustrated symptoms. The COVID- network was largely disjointed, with most of the somatosensory symptoms forming their own cluster with no connections to other symptom groups and fatigue not being connected to any other symptom. The cognitive and affective symptoms in the COVID- network were also largely connected to symptoms from within their own groups; (4) conclusions: These findings suggest that many of the long-term neurobehavioral symptoms of COVID-19 form a discernable network and that headaches, frustration, hearing problems, forgetfulness, and tension are the most central symptoms. Cognitive and behavioral rehabilitation strategies targeting these central symptom network features may hold promise to help fracture the lingering symptom network of COVID-19.

The comparison between the effects of pain education interventions with online and face-to-face exercise and the control group received biomedical education + standardized physical therapy in patients with chronic nonspecific neck pain during COVID-19: protocol for a parallel-group randomized controlled trial.

BACKGROUND: Various psychological issues and serious health concerns during the imposed lockdown by coronavirus disease 2019 (COVID-19) have induced many changes in the treatment of patients. More effective self-management strategies through tele-rehabilitation are suggested to be applied for patients with chronic neck pain to reduce referrals to health cares and disability support through COVID-19. Also, the pain neuroscience education (PNE) approach is an educational method used by health professionals to assist patients in understanding the biology, physiology, and psychosocial factors affecting their pain experience and aligning with the cognitions and beliefs associated with pain and recurrent disability. PNE combined with tele-rehabilitation could be a new solution to encourage patients to manage their condition by themselves and increase the continuity of practice instead of face-to-face sessions. OBJECTIVE: This randomized control trial (RCT) aims to investigate the effects of PNE with online and face-to-face exercise interventions, and the control group received biomedical education + standardized physical therapy on neck pain and disability, psychological factors, and function in non-traumatic chronic neck pain. METHODS/DESIGN: Patients with non-traumatic chronic neck pain (patient-centered care and active involvement of patients and the public) will be recruited via flyers displayed in hospitals and universities to participate in an RCT with two experimental and one control group designed to investigate the effects of PNE with online and face-to-face exercise interventions, and the control group received biomedical education + standardized physical therapy on neck pain and disability, psychological factors, and function in non-traumatic chronic neck pain. The outcomes will be measured at baseline, after PNE, and after 3 months of an exercise intervention. All outcomes are presented as mean ± SD, and statistical significance was set at α level of < 0.05. The normal distribution of the variables was verified by the Kolmogorov-Smirnov test, following a descriptive analysis. DISCUSSION: It seems that PNE plus online and face-to-face exercise interventions are appropriate educational models for the treatment of patients with neck pain during COVID-19. Also, online training seems to encourage patients to continue their treatment. TRIAL REGISTRATION: Iranian Registry of Clinical Trials IRCT20150503022068N5. Registered on 09 September 2021.

The Impact of SARS-CoV-2 Infection on Heart Rate Variability: A Systematic Review of Observational Studies with Control Groups.

Autonomic nervous system (ANS) dysfunction can arise after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and heart rate variability (HRV) tests can assess its integrity. This review investigated the relationship between the impact of SARS-CoV-2 infection on HRV parameters. Comprehensive searches were conducted in four electronic databases. Observational studies with a control group reporting the direct impact of SARS-CoV-2 infection on the HRV parameters in July 2022 were included. A total of 17 observational studies were included in this review. The square root of the mean squared differences of successive NN intervals (RMSSD) was the most frequently investigated. Some studies found that decreases in RMSSD and high frequency (HF) power were associated with SARS-CoV-2 infection or the poor prognosis of COVID-19. Also, decreases in RMSSD and increases in the normalized unit of HF power were related to death in critically ill COVID-19 patients. The findings showed that SARS-CoV-2 infection, and the severity and prognosis of COVID-19, are likely to be reflected in some HRV-related parameters. However, the considerable heterogeneity of the included studies was highlighted. The methodological quality of the included observational studies was not optimal. The findings suggest rigorous and accurate measurements of HRV parameters are highly needed on this topic.

What is the quality of life in patients with long COVID compared to a healthy control group?

Introduction: Many patients have prolonged symptoms after COVID-19 infection, which can affect patient quality of life (QOL). The aim of this study is to determine the quality of life in patients with long COVID, compared with healthy controls. Material and methods: The study was a prospective cross-sectional study using an anonymous online survey. The SF-36 questionnaire was chosen for quality of life measurement. The survey was distributed through the Facebook social media platform targeting groups of patients with long COVID. The control group was made up of physiotherapy and physical education students. Results: There was a significant difference in physical function, with a mean score of 94.9 (±9.4) among the students, compared to long COVID patients with a mean score of 66.2 (±25.4) (p < 0.001). A similar result was found in the physical role (p < 0.001). The overall quality of life score for college students was 578.0 (±111.9), and the overall score for patients with long COVID was 331.9 (±126.9). Conclusions: Patients with long COVID had a lower quality of life compared to the healthy control group, and this was associated with the negative effect of long-COVID. Lower quality of life in patients with long COVID is an important therapeutic goal, which requires attention.

Study of common hypertriglyceridaemia genetic variants and subclinical atherosclerosis in a group of women with SLE and a control group.

OBJECTIVE: SLE is associated with increased cardiovascular risk (CVR). High serum concentrations of triglyceride-rich lipoproteins and apolipoprotein B-rich particles constitute the characteristic dyslipidaemia of SLE. METHODS: A cross-sectional study was conducted to study the relationship between genetic variants involved in polygenic hypertriglyceridaemia, subclinical atherosclerosis and lipoprotein abnormalities. 73 women with SLE and 73 control women age-matched with the case group were recruited (age range 30-75 years). Serum analysis, subclinical atherosclerosis screening studies for the detection of plaque, and genetic analysis of the APOE, ZPR1, APOA5 and GCKR genes were performed. RESULTS: Triglyceride concentrations and the prevalence of hypertension, dyslipidaemia and carotid atherosclerosis were higher in women with SLE than in the control group. Multivariate logistic regression showed that CC homozygosity for the GCKR rs1260326 gene (OR=0.111, 95% CI 0.015 to 0.804, p=0.030) and an increase of 1 mmol/L in triglyceride concentrations were associated with a greater risk of carotid plaque in women with SLE (OR=7.576, 95% CI 2.415 to 23.767, p=0.001). CONCLUSIONS: GCKR CC homozygosity (rs1260326) and serum triglyceride concentrations are independently associated with subclinical carotid atherosclerosis in women with SLE. Subclinical carotid atherosclerosis is also more prevalent in these women compared with the control group. The study of GCKR rs1260326 gene variants may contribute to more precise assessment of CVR and modulation of the intensity of lipid-lowering treatment in patients with SLE.

Mesenchymal stromal cell therapy for COVID-19-induced ARDS patients: a successful phase 1, control-placebo group, clinical trial.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is the devastating complication of the new COVID-19 pandemic, directly correlated with releasing large amounts of inflammatory cytokines. Due to their immunoregulatory features, mesenchymal stromal cells (MSCs) provide a promising approach against this disease. In this regard, this study was designed as a single-center, open-label, phase 1 clinical trial with a control group to examine the safety and explore the possible potency of three injections of umbilical cord-derived MSCs (UC-MSCs) in mild-moderate COVID-19-induced ARDS patients. METHODS: Twenty confirmed COVID-19 patients with mild-to-moderate ARDS degree entered the study and were divided into two groups: control group (standard care) and intervention group (standard care + UC-MSCs). The patients received three intravenous infusions of UC-MSCs (1 × [Formula: see text] cells/kg BW per injection) every other day. Respiratory markers, CRP levels and specific serum cytokines were assessed four times (days of 0, 5, 10 and 17) during the 17-day follow-up period. RESULTS: During the study, there were no serious adverse effects after cell transplantations. Besides, significant improvement in SPO2/FIO2 ratio and serum CRP levels was observed. On the other hand, a significant decrease (P < 0.05) in serum cytokine levels of IL-6, IFN-g, TNF-α, IL-17 A and a significant increase in serum cytokine levels of TGF-B, IL-1B and IL-10 were observed. Also, no significant changes were observed in CT scan images of patients during the study period. CONCLUSION: Our obtained results demonstrated that multiple intravenous transplantations of allogenic UC-MSCs in non-severe COVID-19-induced ARDS patients are a safe procedure. In addition, this intervention is a hopeful approach to decline cytokine storm and recover respiratory functions. Indeed, more clinical trials with larger sample sizes are required to confirm these results. Trial registration This clinical trial was registered with the Iranian Registry of Clinical Trials (ID: IRCT20160809029275N1 at 2020.05.30).

Health-Related Quality of Life Mildly Affected Following COVID-19: a Retrospective Pre-post Cohort Study with a Propensity Score-Matched Control Group.

IMPORTANCE: Long-term health effects have been indicated following COVID-19; however, the impact of COVID-19 on health-related quality of life (HRQOL), including who may experience ongoing symptoms, is unknown. OBJECTIVE: To identify change in HRQOL following COVID-19 compared to pre-infection HRQOL and a matched control group, and identify predictors of patients who worsen. DESIGN: Retrospective pre-post cohort study with a matched control group. SETTING: Large healthcare system in northeast Ohio. PARTICIPANTS: A total of 3,690 adult patients diagnosed with COVID-19 who completed HRQOL surveys during routine care for ambulatory visits before and after infection. Propensity-score 1:1 match was utilized to identify controls without COVID who completed HRQOL at two time points. MAIN OUTCOMES: HRQOL was assessed with PROMIS Global Health: global mental and physical health summary scores. Pre- and post-COVID PROMIS Global Health was completed as part of routine care from 1/1/2019 to 2/29/2020 and 4/4/2020 to 11/1/2021, respectively, and extracted from the electronic health record. RESULTS: COVID-19 patients (mean age 53±15; 66% female) completed PROMIS Global Health in the year prior (median 11.1 months) and after diagnosis (median 7.8 months). Compared to before infection, COVID-19 patients had a significant reduction in global mental health and stable global physical health (-0.85 and 0.05 T-score points, respectively) with clinically meaningful reduction (≥5 T-score points) experienced by 27% and 23% of patients, respectively. Predictors of worsening global health included being female, having depression, being hospitalized for COVID-19, and better pre-COVID global health. Compared to the control group, there was significantly worse global mental and physical health decline following COVID-19 (-0.53 and -0.37 T-score points, respectively). CONCLUSIONS AND RELEVANCE: A quarter of patients with COVID-19 experienced meaningful reductions in HRQOL. Reductions in global mental and physical health were modest, although significantly worse than a control group. Additionally, identified predictors of patients who worsen may assist clinicians when counseling patients of their risk of worse HRQOL following COVID-19.

Prospective, observational, single-centre cohort study with an independent control group matched for age and sex aimed at investigating the significance of cholinergic activity in patients with schizophrenia: study protocol of the CLASH-study.

INTRODUCTION: Alterations in the cholinergic metabolism may cause various clinical symptoms of schizophrenia. In addition to the 'monoamine hypothesis,' neuroinflammation is also discussed as a cause of schizophrenia. To date, there has been no evidence of alterations in the central cholinergic transmitter balance in patients with schizophrenia under clinical conditions. By contrast, studies in critically ill patients have established the measurement of acetylcholinesterase activity as a suitable surrogate parameter of central cholinergic transmitter balance/possible pathophysiological changes. Butyrylcholinesterase activity has been established as a parameter indicating possible (neuro)inflammatory processes. Both parameters can now be measured using a point-of-care approach. Therefore, the primary objective of this study is to investigate whether acetylcholinesterase and butyrylcholinesterase activity differs in patients with various forms of schizophrenia. Secondary objectives address the possible association between acetylcholinesterase and butyrylcholinesterase activity and (1) schizophrenic symptoms using the Positive and Negative Syndrome Scale, (2) the quantity of antipsychotics taken and (3) the duration of illness. METHODS AND ANALYSIS: The study is designed as a prospective, observational cohort study with one independent control group. It is being carried out at the Department of Psychiatry and Psychotherapy III, Ulm University Hospital, Germany. Patient enrolment started in October 2020, and the anticipated end of the study is in January 2022. The enrolment period was set from October 2020 to December 2021 (extension required due to SARS-CoV-2 pandemic). The sample size is calculated at 50 patients in each group. Esterase activity is measured on hospital admission (acute symptomatology) and after referral to a postacute ward over a period of three consecutive days. The matched control group will be created after reaching 50 patients with schizophrenia. This will be followed by a comprehensive statistical analysis of the data set. ETHICS AND DISSEMINATION: The study was registered prospectively in the German Clinical Trials Register (DRKS-ID: DRKS00023143,URL: https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00023143) after approval by the ethics committee of the University of Ulm, Germany Trial Code No. 280/20. TRIAL REGISTRATION NUMBER: DRKS00023143; Pre-results.

Comparison of Serum Total IgA Levels in Severe and Mild COVID-19 Patients and Control Group.

BACKGROUND: The present study aimed to compare serum total IgA levels between severe and mild COVID-19 patients' groups and the control group. METHODS: In this cross-sectional study, 216 definite severe COVID-19 patients (as the inpatient group), 183 subjects with positive specific COVID-19 IgG with mild or no symptoms as the (outpatient group), and 203 healthy subjects with negative specific serology, as the control group were investigated. The cases' laboratory data were collected, and thereafter, statistical tests, including independent samples t test, ANOVA test, and post hoc test, were performed using SPSS software version 22. RESULT: The mean ± SD of IgA in all the included subjects was 2.23 ± 0.78 (g/L). According to the obtained results, there were statistically significant changes in IgA among the three study groups (P value < 0.05). This difference was significant between both outpatient and inpatient groups (P value < 0.05). The mean ± SD of serum IgG in all the subjects was calculated as 15.83 ± 5.73 (g/L). A strong statistically significant change was also seen in IgG among all three groups (P value < 0.001). Of note, there was a significant negative correlation between IgG and IgA total titers of the outpatient group (P value = 0.011*r = - 0.188). CONCLUSION: It was shown that the total serum IgA and IgG levels are significantly associated with the severity of COVID-19 infection. As well, we found that total serum IgA and IgG are associated with the severity of illness. Since a low level of IgA is asymptomatic and high frequent in Iran and other countries, we suggest the evaluation of serum IgA levels in high-risk people and strengthening immune system in subjects with a low level of IgA, in order to reduce the rate of death. In this regard, oral or nasal mucosal vaccines in combination with parenteral vaccination are recommended due to increasing immunity versus COVID-19 by further secretion of the IgA antibody and preventing virus transmission.

The effects of an intervention to improve mental health during the COVID-19 quarantine: comparison with a COVID control group, and a pre-COVID intervention group.

ObjectiveThe COVID-19 pandemic has constituted an unprecedented challenge to society and science and it has provided an unexpected opportunity to explore the effects of a positive intervention in times of adversity and confinement. The goal was to evaluate the effects of a theory driven group intervention to cultivate mental health and flourishing. Design: A pre post design with three groups (151 individuals) was conducted, including an experimental group that received the intervention during the pandemic, a pre-COVID intervention group, and a COVID control group. Main Outcome Measures: Based on Keyes' concept of positive mental health, measures of subjective, psychological and social well-being were obtained, as well as an indicator of psychological distress (GHQ12). Results: Intervention groups showed an increase in well-being and the COVID control group a decrease. Change scores revealed significant differences. Overall percentage of individuals at risk of ill health in baseline was 25.2%, but after the intervention, the COVID control group reached 64.1%. Conclusions: Despite the limitations, the present findings suggest that interventions to sustain and improve mental health in times of crisis and adversity can be an effective approach.

COVID-19 vaccine trials: The potential for "hybrid" analyses.

BACKGROUND: Although several COVID-19 vaccines have been found to be effective in rigorous evaluation and have emerging availability in parts of the world, their supply will be inadequate to meet international needs for a considerable period of time. There also will be continued interest in vaccines that are more effective or have improved scalability to facilitate mass vaccination campaigns. Ongoing clinical testing of new vaccines also will be needed as variant strains continue to emerge that may elude some aspects of immunity induced by current vaccines. Randomized clinical trials meaningfully enhance the efficiency and reliability of such clinical testing. In clinical settings with limited or no access to known effective vaccines, placebo-controlled randomized trials of new vaccines remain a preferred approach to maximize the reliability, efficiency and interpretability of results. When emerging availability of licensed vaccines makes it no longer possible to use a placebo control, randomized active comparator non-inferiority trials may enable reliable insights. METHODS: In this article, "hybrid" methods are proposed to address settings where, during the conduct of a placebo-controlled trial, a judgment is made to replace the placebo arm by a licensed COVID-19 vaccine due to emerging availability of effective vaccines in regions participating in that trial. These hybrid methods are based on proposed statistics that aggregate evidence to formally test as well as to estimate the efficacy of the experimental vaccine, by combining placebo-controlled data during the first period of trial conduct with active-controlled data during the second period. RESULTS: Application of the proposed methods is illustrated in two important scenarios where the active control vaccine would become available in regions engaging in the experimental vaccine's placebo-controlled trial: in the first, the active comparator's vaccine efficacy would have been established to be 50%-70% for the 4- to 6-month duration of follow-up of its placebo-controlled trial; in the second, the active comparator's vaccine efficacy would have been established to be 90%-95% during that duration. These two scenarios approximate what has been seen with adenovirus vaccines or mRNA vaccines, respectively, assuming the early estimates of vaccine efficacy for those vaccines would hold over longer-term follow-up. CONCLUSION: The proposed hybrid methods could readily play an important role in the near future in the design, conduct and analysis of randomized clinical trials performed to address the need for multiple additional vaccines reliably established to be safe and have worthwhile efficacy in reducing the risk of symptomatic disease from SARS-CoV-2 infections.

Selection of the Appropriate Control Group Is Essential in Evaluating the Cytokine Storm in COVID-19.

BACKGROUND/AIM: Lately, studies have reported contradicting results on the cytokine storm seen in critically-ill COVID-19 patients. Depending on the control group used, cytokines have been found to be higher, similar or even lower in COVID-19 compared to critical illnesses associated with elevated cytokine concentrations. However, most of these studies do not take into account critical illness severity. Hence, we decided to compare cytokine levels in critically-ill COVID-19 patients and critically-ill patients of a general intensive care unit (ICU), who did not have sepsis or septic shock, but had an equal disease severity. PATIENTS AND METHODS: Interleukin (IL)-6, IL-8, IL-10 and tumour necrosis factor-α (TNF-α) were measured on ICU admission in mechanically ventilated, COVID-19 (N=36) and non-COVID-19 (N=30) patients, who had not received dexamethasone, and had equal critical illness severity. Non-COVID-19 patients did not have sepsis or septic shock. RESULTS: In our case control study, circulating IL-6 and IL-10 were lower, while TNF-α and IL-8 levels were higher in critically-ill COVID-19 patients, compared to critically-ill non-COVID-19 patients. CONCLUSION: It is difficult to infer whether the cytokine storm seen in COVID-19 differs from other critical conditions. It is important to recognize that the conclusions of related studies may depend on control group selection.

A Test-Negative Design with Additional Population Controls Can Be Used to Rapidly Study Causes of the SARS-CoV-2 Epidemic.

Testing of symptomatic persons for infection with severe acute respiratory syndrome coronavirus-2 is occurring worldwide. We propose two types of case-control studies that can be carried out jointly in test settings for symptomatic persons. The first, the test-negative case-control design (TND) is the easiest to implement; it only requires collecting information about potential risk factors for Coronavirus Disease 2019 (COVID-19) from the tested symptomatic persons. The second, standard case-control studies with population controls, requires the collection of data on one or more population controls for each person who is tested in the test facilities, so that test-positives and test-negatives can each be compared with population controls. The TND will detect differences in risk factors between symptomatic persons who have COVID-19 (test-positives) and those who have other respiratory infections (test-negatives). However, risk factors with effect sizes of equal magnitude for both COVID-19 and other respiratory infections will not be identified by the TND. Therefore, we discuss how to add population controls to compare with the test-positives and the test-negatives, yielding two additional case-control studies. We describe two options for population control groups: one composed of accompanying persons to the test facilities, the other drawn from existing country-wide healthcare databases. We also describe other possibilities for population controls. Combining the TND with population controls yields a triangulation approach that distinguishes between exposures that are risk factors for both COVID-19 and other respiratory infections, and exposures that are risk factors for just COVID-19. This combined design can be applied to future epidemics, but also to study causes of nonepidemic disease.

Influenza vaccination and respiratory virus interference among Department of Defense personnel during the 2017-2018 influenza season.

PURPOSE: Receiving influenza vaccination may increase the risk of other respiratory viruses, a phenomenon known as virus interference. Test-negative study designs are often utilized to calculate influenza vaccine effectiveness. The virus interference phenomenon goes against the basic assumption of the test-negative vaccine effectiveness study that vaccination does not change the risk of infection with other respiratory illness, thus potentially biasing vaccine effectiveness results in the positive direction. This study aimed to investigate virus interference by comparing respiratory virus status among Department of Defense personnel based on their influenza vaccination status. Furthermore, individual respiratory viruses and their association with influenza vaccination were examined. RESULTS: We compared vaccination status of 2880 people with non-influenza respiratory viruses to 3240 people with pan-negative results. Comparing vaccinated to non-vaccinated patients, the adjusted odds ratio for non-flu viruses was 0.97 (95% confidence interval (CI): 0.86, 1.09; p = 0.60). Additionally, the vaccination status of 3349 cases of influenza were compared to three different control groups: all controls (N = 6120), non-influenza positive controls (N = 2880), and pan-negative controls (N = 3240). The adjusted ORs for the comparisons among the three control groups did not vary much (range: 0.46-0.51). CONCLUSIONS: Receipt of influenza vaccination was not associated with virus interference among our population. Examining virus interference by specific respiratory viruses showed mixed results. Vaccine derived virus interference was significantly associated with coronavirus and human metapneumovirus; however, significant protection with vaccination was associated not only with most influenza viruses, but also parainfluenza, RSV, and non-influenza virus coinfections.