Breakthrough cases of mpox: One-dose vaccination is associated with milder clinical manifestations

BACKGROUND

Very few studies have investigated the effectiveness of vaccination in decreasing the severity of breakthrough mpox. Our goal was to estimate the strength of the associations between recent mpox vaccination with MVA-BN and various clinical manifestations of the disease.

METHODS

Telephone interviews using standardized questionnaires, upon notification and 28 days later, of the 403 persons with mpox reported to Montreal Public Health in 2022. MVA-BN vaccination data were obtained from the provincial immunization registry. The main outcomes were numbers of skin lesions and body sites affected, other clinical manifestations (OCM) compatible with mpox, complications, and hospitalization.

FINDINGS

155 persons with mpox (39% of 403) had received 1 dose of vaccine at least 14 days before symptom onset. One-dose vaccination, adjusting for age and HIV status, was significantly associated with fewer lesions, sites affected with lesions, and OCMs. HIV-positive persons with breakthrough mpox reported significantly more lesions, sites affected, and OCMs at initial interview, than HIV-negative ones. However, vaccination was associated with a lower risk of all outcomes to the same degree irrespective of HIV status.

INTERPRETATION

One dose of MVA-BN vaccine was about 60% effective in decreasing the frequency and extent of clinical manifestations, among both HIV-positive and HIV-negative persons with breakthrough mpox. Beyond preventing infection, mpox vaccination can be promoted to reduce clinical manifestations in persons at risk for mpox, even if HIV+ .

FUNDING

This work used data obtained as part of Montreal Public Health's 2022 mpox outbreak response and received no external funding.

Single-dose Effectiveness of Mpox Vaccine in Quebec, Canada: Test-negative Design With and Without Adjustment for Self-reported Exposure Risk

INTRODUCTION

During the 2022 mpox outbreak, the province of Quebec, Canada, prioritized first doses for pre-exposure vaccination of people at high mpox risk, delaying second doses due to limited supply. We estimated single-dose mpox vaccine effectiveness (VE) adjusting for virus exposure risk based only on surrogate indicators available within administrative databases (eg, clinical record of sexually transmitted infections) or supplemented by self-reported risk factor information (eg, sexual contacts).

METHODS

We conducted a test-negative case-control study between 19 June and 24 September 2022. Information from administrative databases was supplemented by questionnaire collection of self-reported risk factors specific to the 3-week period before testing. Two study populations were assessed: all within the administrative databases (All-Admin) and the subset completing the questionnaire (Sub-Quest). Logistic regression models adjusted for age, calendar-time and exposure-risk, the latter based on administrative indicators only (All-Admin and Sub-Quest) or with questionnaire supplementation (Sub-Quest).

RESULTS

There were 532 All-Admin participants, of which 199 (37%) belonged to Sub-Quest. With exposure-risk adjustment based only on administrative indicators, single-dose VE estimates were similar among All-Admin and Sub-Quest populations at 35% (95% confidence interval [CI]:-2 to 59) and 30% (95% CI:-38 to 64), respectively. With adjustment supplemented by questionnaire information, the Sub-Quest VE estimate increased to 65% (95% CI:1-87), with overlapping confidence intervals.

CONCLUSIONS

Using only administrative data, we estimate one vaccine dose reduced the mpox risk by about one-third; whereas, additionally adjusting for self-reported risk factor information revealed greater vaccine benefit, with one dose instead estimated to reduce the mpox risk by about two-thirds. Inadequate exposure-risk adjustment may substantially under-estimate mpox VE.

Monkeypox in Montréal: Epidemiology, Phylogenomics, and Public Health Response to a Large North American Outbreak

BACKGROUND

Monkeypox, a viral zoonotic disease, is causing a global outbreak outside of endemic areas.

OBJECTIVE

To characterize the outbreak of monkeypox in Montréal, the first large outbreak in North America.

DESIGN

Epidemiologic and laboratory surveillance data and a phylogenomic analysis were used to describe and place the outbreak in a global context.

SETTING

Montréal, Canada.

PATIENTS

Probable or confirmed cases of monkeypox.

MEASUREMENTS

Epidemiologic, clinical, and demographic data were aggregated. Whole-genome sequencing and phylogenetic analysis were performed for a set of outbreak sequences. The public health response and its evolution are described.

RESULTS

Up to 18 October 2022, a total of 402 cases of monkeypox were reported mostly among men who have sex with men (MSM), most of which were suspected to be acquired through sexual contact. All monkeypox genomes nested within the B.1 lineage. Montréal Public Health worked closely with the affected communities to control the outbreak, becoming the first jurisdiction to offer 1 dose of the Modified Vaccinia Ankara-Bavarian Nordic vaccine as preexposure prophylaxis (PrEP) to those at risk in early June 2022. Two peaks of cases were seen in early June and July (43 and 44 cases per week, respectively) followed by a decline toward near resolution of the outbreak in October. Reasons for the biphasic peak are not fully elucidated but may represent the tempo of vaccination and/or several factors related to transmission dynamics and case ascertainment.

LIMITATIONS

Clinical data are self-reported. Limited divergence among sequences limited genomic epidemiologic conclusions.

CONCLUSION

A large outbreak of monkeypox occurred in Montréal, primarily among MSM. Successful control of the outbreak rested on early and sustained engagement with the affected communities and rapid offer of PrEP vaccination to at-risk persons.

PRIMARY FUNDING SOURCE

None.

Analysis of COVID-19 Risk Following a Ring Vaccination Intervention to Address SARS-CoV-2 Alpha Variant Transmission in Montreal, Canada

IMPORTANCE

Given limited COVID-19 vaccine availability early in the pandemic, optimizing immunization strategies was of paramount importance. Ring vaccination has been used successfully to control transmission of other airborne respiratory viruses.

OBJECTIVE

To assess the association of a ring vaccination intervention on COVID-19 spread in the initial epicenter of SARS-CoV-2 Alpha variant transmission in Montreal, Canada.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study compared COVID-19 daily disease risk in 3 population-based groups of neighborhoods in Montreal, Canada, defined by their intervention-specific vaccine coverage at the neighborhood level: the primary intervention group (500 or more vaccinated persons per 10 000 persons), secondary intervention group (95 to 499), and control group (0 to 50). The groups were compared within each of 3 time periods: before intervention (December 1, 2020, to March 16, 2021), during and immediately after intervention (March 17 to April 17, 2021), and 3 weeks after the intervention midpoint (April 18 to July 18, 2021). Data were analyzed between June 2021 and November 2021.

EXPOSURES

Vaccination targeted parents and teachers of children attending the 32 schools and 48 childcare centers in 2 adjacent neighborhoods with highest local transmission (case counts) of Alpha variant shortly after its introduction. Participants were invited to receive 1 dose of mRNA vaccine between March 22 and April 9, 2021 (before vaccine was available to these age groups).

MAIN OUTCOMES AND MEASURES

COVID-19 risk in 3 groups of neighborhoods based on intervention-specific vaccine coverage.

RESULTS

A total of 11 794 residents were immunized, with a mean (SD) age of 43 (8) years (range, 16-93 years); 5766 participants (48.9%) lived in a targeted neighborhood, and 9784 (83.0%) were parents. COVID-19 risk in the primary intervention group was significantly higher than in the control group before (unadjusted risk ratio [RR], 1.58; 95% CI 1.52-1.65) and during (RR, 1.63; 95% CI, 1.52-1.76) intervention, and reached a level similar to the other groups in the weeks following the intervention (RR, 1.03; 95% CI, 0.94-1.12). A similar trend was observed when restricting to SARS-CoV-2 variants and persons aged 30 to 59 years (before: RR, 1.72; 95% CI, 1.63-1.83 vs after: RR, 1.01; 95% CI, 0.88-1.17).

CONCLUSIONS AND RELEVANCE

Our findings show that ring vaccination was associated with a reduction in COVID-19 risk in areas with high local transmission of Alpha variant shortly after its introduction. Ring vaccination may be considered as an adjunct to mass immunization to control transmission in specific areas, based on local epidemiology.

Systematic review of the accuracy of antibody tests used to screen asymptomatic adults for hepatitis C infection

BACKGROUND

Several expert groups, including the United States Preventive Services Task Force and the Canadian Task Force on Preventive Health Care, have recently examined or are currently examining whether primary care physicians should screen asymptomatic adults for hepatitis C virus (HCV) infection. To inform decision-making on HCV screening, we performed a systematic review of the accuracy of antibody tests compared with other immunoassays and RNA detection for screening asymptomatic adults for HCV infection in Canada.

METHODS

MEDLINE and Embase databases were searched from 1990 to 2016; resulting citations were uploaded into DistillerSR and independently screened by 2 reviewers. Original research studies, systematic reviews and meta-analyses were eligible for inclusion. At least 80% of the study population had to be asymptomatic, nonpregnant, treatment-naïve adults with unknown liver enzyme values and unknown HCV status. Risk of bias was assessed with the use of the Quality Assessment of Diagnostic Accuracy Studies version 2 (QUADAS-2) tool; the quality of the body of evidence was assessed by means of GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.

RESULTS

Of 1537 articles identified, 81 underwent full-text review, and 9 studies met the inclusion criteria. Compared with RNA detection, the sensitivity of the third-generation enzyme-linked immunosorbent assay was variable (61.0%-81.8%), and its specificity was high (97.5%-99.7%). As expected, there were more false-positive results when comparing antibody tests to RNA detection than to other immunoassays. Our GRADE assessment suggested that there was a high concern for risk of bias, particularly verification bias, and substantial inconsistency between studies in terms of their design.

INTERPRETATION

More research is needed to better characterize the accuracy of antibody tests used to screen for HCV infection in the general population. Jurisdictions that recently adopted birth cohort screening for HCV infection are encouraged to evaluate and report on the accuracy of HCV screening tests and screening benefits and harms. PROSPERO registration: no. CRD42016039710.

Validation of Diagnostic Groups Based on Health Care Utilization Data Should Adjust for Sampling Strategy

Supplemental Digital Content is available in the text.

Objective:

Valid measurement of outcomes such as disease prevalence using health care utilization data is fundamental to the implementation of a “learning health system.” Definitions of such outcomes can be complex, based on multiple diagnostic codes. The literature on validating such data demonstrates a lack of awareness of the need for a stratified sampling design and corresponding statistical methods. We propose a method for validating the measurement of diagnostic groups that have: (1) different prevalences of diagnostic codes within the group; and (2) low prevalence.

Methods:

We describe an estimation method whereby: (1) low-prevalence diagnostic codes are oversampled, and the positive predictive value (PPV) of the diagnostic group is estimated as a weighted average of the PPV of each diagnostic code; and (2) claims that fall within a low-prevalence diagnostic group are oversampled relative to claims that are not, and bias-adjusted estimators of sensitivity and specificity are generated.

Application:

We illustrate our proposed method using an example from population health surveillance in which diagnostic groups are applied to physician claims to identify cases of acute respiratory illness.

Conclusions:

Failure to account for the prevalence of each diagnostic code within a diagnostic group leads to the underestimation of the PPV, because low-prevalence diagnostic codes are more likely to be false positives. Failure to adjust for oversampling of claims that fall within the low-prevalence diagnostic group relative to those that do not leads to the overestimation of sensitivity and underestimation of specificity.

Clinician-patient agreement about the work disability problem of patients having persistent pain: why it matters

BACKGROUND

Studies from different fields documenting the differences between clinicians' and workers' representations have not elucidated where the differences exist or how they can be resolved.

PURPOSE

To define and describe scenarios depicting the differences between clinical judgment, workers' representations about their disability and clinicians' interpretations of these representations.

METHODS

A multiple case-study design was used. Semi-structured prospective interviews were conducted at four points in time, with five clinicians managing 12 cases of workers having persistent pain and participating in an evidence-based work rehabilitation program.

RESULTS

Four scenarios depicting differences in representations were found, but not all the differences necessarily had a negative impact on the program outcomes. For the clinicians, clear identification of the problem was important to allow for the use of concrete, pragmatic strategies. For the workers, congruence between the proposed strategy and their representations was crucial.

CONCLUSION

During rehabilitation, the objectives must be acceptable to both parties or the proposed strategy must, at least, make sense to the patient.

Factors associated with generalized anxiety in workers undergoing work rehabilitation for persistent musculoskeletal pain

PURPOSE

To document in workers having a work disability due to a musculoskeletal disorder (MSD), the presence and variation over time of their intolerance of uncertainty and its maintenance factors as defined in Dugas et al.'s generalized anxiety disorder (GAD) model, i.e. worries, negative problem orientation, beliefs about the usefulness of worrying, cognitive avoidance and their consequences on depressive symptoms.

METHODS

An observational, prospective repeated-measures design was retained. Thirty-nine workers with an MSD having caused a work absence of over three months and who were beginning a work rehabilitation program were recruited and evaluated at four moments (beginning of rehabilitation program, first hours of work exposure, 50% of regular working hours and end of rehabilitation program). Validated self-report questionnaires measuring intolerance of uncertainty and its maintenance factors were administered. Finally, the Worry and Anxiety Questionnaire measured the presence and intensity of GAD symptoms as defined in the DSM-IV-TR.

RESULTS

Fifty percent of the workers initially exhibited GAD symptoms. Concerning the variation over time, improvements were noted in all GAD-related factors during the program, particularly with the first hours of work exposure. At the end of rehabilitation, only 21% of the participants still met GAD diagnostic criteria.

CONCLUSION

Workers with an MSD causing a work disability averaging one year in length and enrolled in a work rehabilitation program exhibited a high level of anxiety at the beginning of the work rehabilitation program. Workers perceived a usefulness in worrying and presented some intolerance of uncertainty and some cognitive avoidance strategies. According to Dugas et al.'s GAD model, the intensity of the symptoms associated with GAD development and maintenance factors was, however, not typical of a GAD. IMPLICATION FOR REHABILITATION: A reconceptualization of the problem in terms of reducing the work disability rather than reducing pain may constitute a promising avenue to reduce anxiety symptoms. Future studies should look at the specific impact of work exposure, not only on pain symptoms but also on worries. The high level of anxiety and the reported worries by workers stresses the importance of studying the hypothesis of a workplace phobia in order to improve clinical practice guidelines.

Patient, physician, encounter, and billing characteristics predict the accuracy of syndromic surveillance case definitions

BACKGROUND

Syndromic surveillance systems are plagued by high false-positive rates. In chronic disease monitoring, investigators have identified several factors that predict the accuracy of case definitions based on diagnoses in administrative data, and some have even incorporated these predictors into novel case detection methods, resulting in a significant improvement in case definition accuracy. Based on findings from these studies, we sought to identify physician, patient, encounter, and billing characteristics associated with the positive predictive value (PPV) of case definitions for 5 syndromes (fever, gastrointestinal, neurological, rash, and respiratory (including influenza-like illness)).

METHODS

The study sample comprised 4,330 syndrome-positive visits from the claims of 1,098 randomly-selected physicians working in Quebec, Canada in 2005-2007. For each visit, physician-facilitated chart review was used to assess whether the same syndrome was present in the medical chart (gold standard). We used multivariate logistic regression analyses to estimate the association between claim-chart agreement about the presence of a syndrome and physician, patient, encounter, and billing characteristics.

RESULTS

The likelihood of the medical chart agreeing with the physician claim about the presence of a syndrome was higher when the treating physician had billed many visits for the same syndrome recently (ORper 10 visit, 1.05; 95% CI, 1.01-1.08), had a lower workload (ORper 10 claims, 0.93; 95% CI, 0.90-0.97), and when the patient was younger (ORper 5 years of age, 0.96; 95% CI, 0.94-0.97), and less socially deprived (ORmost versus least deprived, 0.76; 95% CI, 0.60-0.95).

CONCLUSIONS

Many physician, patient, encounter, and billing characteristics associated with the PPV of surveillance case definition are accessible to public health, and could be used to reduce false-positive alerts by surveillance systems, either by focusing on the data most likely to be accurate, or by adjusting the observed data for known biases in diagnosis reporting and performing surveillance using the adjusted values.

Health and illness representations of workers with a musculoskeletal disorder-related work disability during work rehabilitation: a qualitative study

INTRODUCTION

Distinctions between disease and illness have been criticized for being too theoretical. In practice, however, it may help explain gaps in understanding and miscommunication between health care professionals and patients/injured workers, since each has their own perception of reality. To reduce the gap between health care professionals and patients in understanding the definition of disease, this paper documents general representations of health, illness and work-related musculoskeletal disorders and their influence on the work rehabilitation program.

METHODS

A qualitative methodology was used. Semi-structured interviews were conducted with 16 participants (male, female) recruited when they were starting an intensive interdisciplinary work rehabilitation program for chronic pain due to a musculoskeletal disorder. Interviews were performed at three points during the program and 1 month after discharge.

RESULTS

First, participants described health and illness in terms of: (1) illness prototype; (2) the absence or presence of symptoms; (3) physical health and capacities; (4) engaging in a healthy lifestyle; (5) maintaining independence; (6) preserving mental well-being; and (7) healing from accidents or injuries. A second observation was that rehabilitation success depended on workers transitioning from a less mechanistic to a more functional view of health.

CONCLUSION

This study highlights the importance of identifying and acknowledging workers' health, illness and WRMSD representations to facilitate their return to work.

Accuracy of syndrome definitions based on diagnoses in physician claims

Background

Community clinics offer potential for timelier outbreak detection and monitoring than emergency departments. However, the accuracy of syndrome definitions used in surveillance has never been evaluated in community settings. This study's objective was to assess the accuracy of syndrome definitions based on diagnostic codes in physician claims for identifying 5 syndromes (fever, gastrointestinal, neurological, rash, and respiratory including influenza-like illness) in community clinics.

Methods

We selected a random sample of 3,600 community-based primary care physicians who practiced in the fee-for-service system in the province of Quebec, Canada in 2005-2007. We randomly selected 10 visits per physician from their claims, stratifying on syndrome type and presence, diagnosis, and month. Double-blinded chart reviews were conducted by telephone with consenting physicians to obtain information on patient diagnoses for each sampled visit. The sensitivity, specificity, and positive predictive value (PPV) of physician claims were estimated by comparison to chart review.

Results

1,098 (30.5%) physicians completed the chart review. A chart entry on the date of the corresponding claim was found for 10,529 (95.9%) visits. The sensitivity of syndrome definitions based on diagnostic codes in physician claims was low, ranging from 0.11 (fever) to 0.44 (respiratory), the specificity was high, and the PPV was moderate to high, ranging from 0.59 (fever) to 0.85 (respiratory). We found that rarely used diagnostic codes had a higher probability of being false-positives, and that more commonly used diagnostic codes had a higher PPV.

Conclusions

Future research should identify physician, patient, and encounter characteristics associated with the accuracy of diagnostic codes in physician claims. This would enable public health to improve syndromic surveillance, either by focusing on physician claims whose diagnostic code is more likely to be accurate, or by using all physician claims and weighing each according to the likelihood that its diagnostic code is accurate.

Transforming the meaning of pain: an important step for the return to work

Previous studies have found illness representations to be associated with the degree to which patients adopt health behaviours. Surprisingly, pain representations, especially those in a work rehabilitation context, have rarely been explored.

OBJECTIVE

To conduct a thorough investigation of the pain representations held by workers who were on sick leave due to persistent musculoskeletal pain during the process of an intensive work rehabilitation program.

METHODS

Qualitative semi-structured interviews were conducted with 16 participants (male, female), three times during the program and one month after discharge. Data analysis was based on a narrative approach.

RESULTS

Throughout the process, pain representation was an indicator of the type of action the participants were ready to take to control the immediate or possible consequences of their pain. Using the context of a work rehabilitation trajectory we identified the differential impact of reconstruction or status quo in pain representations that eventually led to a return to work, or not.

DISCUSSION

This study highlights the importance of identifying and acknowledging workers' pain representations in facilitating their return to work.

Accuracy of physician billing claims for identifying acute respiratory infections in primary care

OBJECTIVE

To assess the accuracy of physician billing claims for identifying acute respiratory infections in primary care. STUDY SETTING. Nine primary care physician practices in Montreal, Canada (2002-2005).

STUDY DESIGN

A validation study was carried out to compare diagnoses in 3,526 physician billing claims with diagnoses documented in the corresponding patient medical records.

DATA COLLECTION

In-office medical record abstraction.

PRINCIPAL FINDINGS

Claims had a high positive predictive value (PPV), negative predictive value, and specificity for identifying respiratory infections; however, their sensitivity was below 50 percent. Large variation in sensitivity and PPV was observed among physicians.

CONCLUSIONS

Because claims data are now routinely used to monitor antibiotic prescribing in primary care, future research should determine if acute respiratory infection diagnoses are missing from claims at random, or if bias is present.

Surveillance for Newly Emerging Viruses

Surveillance is a fundamental tool for public health, producing information to guide actions. Modern surveillance tends to follow health measures such as the incidence of a disease or syndrome or even the occurrence of health-related behaviors. There are many reasons for conducting surveillance, and the data collected and the approach taken to analyzing those data are both influenced by the overall goal of a surveillance system. Surveillance systems aims mainly at detection also provide information that may be useful for other purposes. The goal of detecting an outbreak of a newly emerging virus, places specific demands on the type of data collected and the types of analysis performed. All approaches to surveillance share some common principles. While some of the underlying methods used in public health surveillance have evolved considerably in recent years, the general approach to surveillance has remained relatively constant. At a fundamental level, surveillance aims to (1) identify individual cases, (2) detect population patterns in identified cases, and then (3) convey information to decision-makers about population health patterns.