Measles surveillance in Canada: 2015

Effect of homophily on coupled behavior-disease dynamics near a tipping point

Understanding the interplay between social activities and disease dynamics is crucial for effective public health interventions. Recent studies using coupled behavior-disease models assumed homogeneous populations. However, heterogeneity in population, such as different social groups, cannot be ignored. In this study, we divided the population into social media users and non-users, and investigated the impact of homophily (the tendency for individuals to associate with others similar to themselves) and online events on disease dynamics. Our results reveal that homophily hinders the adoption of vaccinating strategies, hastening the approach to a tipping point after which the population converges to an endemic equilibrium with no vaccine uptake. Furthermore, we find that online events can significantly influence disease dynamics, with early discussions on social media platforms serving as an early warning signal of potential disease outbreaks. Our model provides insights into the mechanisms underlying these phenomena and underscores the importance of considering homophily in disease modeling and public health strategies.

[Genetic diversity of the mumps viruses (Paramyxoviridae: Orthorubulavirus: Mumps orthorubulavirus): an overview]

Mumps is an infectious disease controlled by specific vaccine prophylaxis. To date, its social and epidemiological significance remains high. This is evidenced by the process of developing and implementing into the health care practices of many countries a set of measures for surveillance of mumps. In the Russian Federation, the National Program «Elimination of measles and rubella and achievement of sporadic morbidity with epidemic mumps in the Russian Federation (2021-2025)» and the national plan for its implementation were adopted in 2021. The basis for the adoption of these documents was the development of the domestic trivalent vaccine for the prevention of measles, rubella and mumps, Vaktrivir, and the start of its clinical application. The availability of this vaccine will make the epidemiological surveillance of mumps to be a part of the existing system of appropriate measures for measles and rubella. The fulfillment of this set of tasks involves the study of the molecular epidemiology of the mumps virus (MuV) with possible subsequent implementation of its methodology into the surveillance actions. In this connection, this work was aimed at presenting the data on global genetic diversity of MuV as well as its genotyping methods in a systematized form. The analysis of MuV global genetic diversity in different years will be the starting point in the subsequent development of approach to monitoring virus strains circulating in the Russian Federation.

Revisiting the 2014-15 Disneyland measles outbreak and its influence on pediatric vaccinations

The 2014-15 Disneyland measles outbreak that began at the California theme park in December 2014 sparked an international conversation regarding measles, vaccine hesitancy, and vaccine policies. The outbreak capped a year with the highest number of measles cases reported in two decades and came amidst increasing trends in nonmedical vaccine exemptions in California and elsewhere. Because of its sensational story line and spread among unvaccinated populations, the outbreak received a high level of media coverage that focused on vaccine hesitancy as a primary driver of the outbreak. This media coverage and the ostensible public support for vaccines that followed led some to hypothesize that the outbreak might have a "Disneyland effect," or a positive influence on the uptake of pediatric measles vaccine. This article reviews the facts of the outbreak and its context, and explores the evidence for the Disneyland outbreak causing an influence on U.S. pediatric vaccine-related beliefs and behaviors.

Evaluation of Diagnostic Accuracy of Eight Commercial Assays for the Detection of Measles Virus-Specific IgM Antibodies

The World Health Organization (WHO) has targeted measles for global eradication through mass immunization. For effective monitoring of eradication targets, high-quality surveillance is needed. The detection of IgM antibodies, specific to the measles virus, with the use of commercial enzyme-linked immunosorbent assays (ELISA or EIA) is broadly used within the WHO global measles and rubella laboratory network for laboratory confirmation, and in particular, ELISA kits manufactured by Siemens (Enzygnost kits) have been primarily used. Spurred by the discontinuation of these kits, this study aims to report on the clinical sensitivity and specificity of comparable commercial ELISA kits and one automated chemiluminescent immunoassay (CLIA) method. A panel of 239 serum samples was assembled that included sera from confirmed measles cases (n = 50) and probable post-MMR vaccine response (n = 2). Measles-negative sera (n = 187) were collected from individuals presenting with other fever and rash illnesses. A total of 7 ELISA kits (Euroimmun native antigens and recombinant nucleoprotein, IBL, Clin-Tech Microimmune, NovaTec NovaLisa, Serion, and Siemens Enzygnost) and one CLIA method (DiaSorin LIAISON XL) were evaluated. The ELISA kits included two IgM capture methods and five indirect methods. Calculated sensitivities and specificities ranged from 75.0% to 98.1% and 86.6% to 99.5%, respectively. The parvovirus B19 IgM positive sera were noted to cause false-positive results, particularly for the ELISA kits from Serion and NovaLisa; specificities for this subset of samples ranged from 51.4% to 100.0%. The capture IgM ELISA methods provided the best combination of sensitivity and specificity.

A validated modification of the vaccine hesitancy scale for childhood, influenza and HPV vaccines

INTRODUCTION

Vaccine hesitancy contributes to outbreaks of preventable disease worldwide. The Vaccine Hesitancy Scale (VHS), developed by the international WHO SAGE Working Group, has been validated previously for measuring hesitancy towards childhood vaccines; some psychometric properties were suboptimal.

METHODS

We collected data using large, nationally-representative samples of parents in the U.S. We adapted the VHS items, and additional hesitancy items, to assess hesitancy towards influenza and HPV vaccines in addition to routine childhood vaccines. We then used exploratory and confirmatory factor analysis to identify latent constructs and create modified scales for childhood (VHS-child), influenza (VHS-flu) and HPV (VHS-HPV) vaccines with improved psychometric properties. Finally, we compared hesitancy scores on the VHS-child, VHS-flu, and VHS-HPV, to self-reported receipt of each vaccine category, and compared subscale scores to assess whether drivers of hesitancy differed by vaccine category.

RESULTS

2052 parents of children <18 years old completed the VHS-child and VHS-flu while 2020 parents of adolescents completed the VHS-HPV. A two-factor structure of 'risks' and a 'lack of confidence' was found for each vaccine category. Slight modifications to the VHS improved psychometric properties. Hesitancy was strongly associated with vaccine receipt: e.g., 76% of parents not hesitant towards influenza vaccine had vaccinated their child the past season, versus 9% of hesitant parents (p < 0.0001). Subscale scores also differed significantly between vaccines: lack of confidence was greater towards influenza (Median (IQR): 2.0 (1.2, 3.3)) and HPV (2.0 (1.3, 3.0)) vaccines than childhood (1.2 (1.0, 1.8), p < 0.0001 for both) vaccines; perceived risks of HPV vaccines (2.7 (1.7, 3.7)) were greater than for childhood vaccines (2.0 (1.3, 3.0), p < 0.0001).

CONCLUSIONS

Our modified VHS scales perform well psychometrically and allow for consistent measurement of the extent and reasons for hesitancy between vaccine categories. We suggest that future work use these scales to examine hesitancy towards other vaccines and to monitor hesitancy over time.

Parental Hesitancy About Routine Childhood and Influenza Vaccinations: A National Survey

BACKGROUND AND OBJECTIVES

The World Health Organization has designated vaccine hesitancy as 1 of the 10 leading threats to global health, yet there is limited current national data on prevalence of hesitancy among US parents. Among a nationally representative sample of US parents, we aimed to (1) assess and compare prevalence of hesitancy and factors driving hesitancy for routine childhood and influenza vaccination and (2) examine associations between sociodemographic characteristics and hesitancy for routine childhood or influenza vaccination.

METHODS

In February 2019, we surveyed families with children using the largest online panel generating representative US samples. After weighting, we assessed hesitancy using a modified 5-point Vaccine Hesitancy Scale and labeled parents as hesitant if they scored >3.

RESULTS

A total of 2176 of 4445 parents sampled completed the survey (response rate 49%). Hesitancy prevalence was 6.1% for routine childhood and 25.8% for influenza vaccines; 12% strongly and 27% somewhat agreed they had concerns about serious side effects of both routine childhood and influenza vaccines. A total of 70% strongly agreed that routine childhood vaccines are effective versus 26% for influenza vaccine (P < .001). In multivariable models, an educational level lower than a bachelor's degree and household income <400% of the federal poverty level predicted hesitancy about both routine childhood and influenza vaccines.

CONCLUSIONS

Almost 1 in 15 US parents are hesitant about routine childhood vaccines, whereas >1 in 4 are hesitant about influenza vaccine. Furthermore, 1 in 8 parents are concerned about vaccine safety for both routine childhood and influenza vaccines, and only 1 in 4 believe influenza vaccine is effective. Vaccine hesitancy, particularly for influenza vaccine, is prevalent in the United States.

Measles Outbreak in Unvaccinated and Partially Vaccinated Children and Adults in the United States and Canada (2018-2019): A Narrative Review of Cases

Since 2018 and currently in 2019, the United States and Canada experienced a rapidly spreading measles virus outbreak. The developing outbreak may be due to a lack of vaccination, an inadequate dosage of measles (MMR) vaccine, clusters of intentionally under-vaccinated children, imported measles from global travel, and from those who are immunocompromised or have other life-threatening diseases. The infection originated mainly from travelers who acquired measles abroad and has thus led to a major outbreak and health concern not only in the United States and Canada but also in other parts of the world. According to World Health Organization, from January 2019 through September 2019, 1234 cases of measles have been reported in the United States and 91 reported cases in Canada, while in 2018, 372 and 28 cases were reported in the United States and Canada, respectively. A potential driving factor to the increased cases maybe because fewer children have been vaccinated over the last number of years in both countries. This article is a narrative review of cases discussing the measles outbreak among partially vaccinated and unvaccinated children and adults in the United States and Canada in 2018 and 2019.

Measles Antibody Levels in Young Infants

BACKGROUND

Infants are often assumed to be immune to measles through maternal antibodies transferred during pregnancy and, in many countries, receive their first measles-containing vaccine at 12 to 15 months. Immunity may wane before this time in measles-eliminated settings, placing infants at risk for measles and complications. We investigated humoral immunity to measles in infants <12 months of age in Ontario, Canada.

METHODS

We selected sera collected at a tertiary pediatric hospital from infants <12 months who were born at ≥37 weeks' gestational age. We excluded infants with conditions that affect antibody levels. We selected ≤25 sera from 8 predetermined age bands and tested them for measles-neutralizing antibody using the plaque-reduction neutralization test. We calculated the proportion immune at each age band, and predictors of infant susceptibility were assessed by using multivariable logistic regression and Poisson regression.

RESULTS

Of 196 infant sera, 56% (110 of 196) were from boys, and 35% (69 of 196) were from infants with underlying medical conditions. In the first month, 20% (5 of 25) of infants had antibodies below the protective threshold, which increased to 92% (22 of 24) by 3 months. By 6 months, all infants had titers below the protective threshold. In a multivariable analysis, infant age was the strongest predictor of susceptibility (odds ratio = 2.13 for each additional month increase; 95% confidence interval: 1.52-2.97).

CONCLUSIONS

Most infants were susceptible to measles by 3 months of age in this elimination setting. Our findings inform important policy discussions relating to the timing of the first dose of measles-containing vaccine and infant postexposure prophylaxis recommendations.

User-Driven Comments on a Facebook Advertisement Recruiting Canadian Parents in a Study on Immunization: Content Analysis

Background

More people are searching for immunization information online and potentially being exposed to misinformation and antivaccination sentiment in content and discussions on social media platforms. As vaccination coverage rates remain suboptimal in several developed countries, and outbreaks of vaccine-preventable diseases become more prevalent, it is important that we build on previous research by analyzing themes in online vaccination discussions, including those that individuals may see without actively searching for information on immunization.

Objective

The study aimed to explore the sentiments and themes behind an unsolicited debate on immunization in order to better inform public health interventions countering antivaccination sentiment.

Methods

We analyzed and quantified 117 user-driven open-ended comments on immunization posted in the Comments section of a Facebook advertisement that targeted Canadian parents for recruitment into a larger study on immunization. Then, 2 raters coded all comments using content analysis.

Results

Of 117 comments, 85 were posted by unique commentators, with most being female (65/85, 77%). The largest proportion of the immunization comments were positive (51/117, 43.6%), followed by negative (41/117, 35.0%), ambiguous (20/117, 17.1%), and hesitant (5/117, 4.3%). Inaccurate knowledge (27/130, 20.8%) and misperceptions of risk (23/130, 17.7%) were most prevalent in the 130 nonpositive comments. Other claims included distrust of pharmaceutical companies or government agencies (18/130, 13.8%), distrust of the health care system or providers (15/130, 11.5%), past negative experiences with vaccination or beliefs (10/130, 7.7%), and attitudes about health and prevention (10/130, 7.7%). Almost 40% (29/74, 39%) of the positive comments communicated the risks of not vaccinating, followed by judgments on the knowledge level of nonvaccinators (13/74, 18%). A total of 10 positive comments (10/74, 14%) specifically refuted the link between autism and vaccination.

Conclusions

The presence of more than 100 unsolicited user-driven comments on a platform not intended for discussion, nor providing any information on immunization, illustrates the strong sentiments associated with immunization and the arbitrariness of the online platforms used for immunization debates. Health authorities should be more proactive in finding mechanisms to refute misinformation and misperceptions that are propagating uncontested online. Online debates and communications on immunization need to be identified by continuous monitoring in order for health authorities to understand the current themes and trends, and to engage in the discussion.