Halting the pandemic outside 'CORTINA2021' alpine world ski championships: a challenge for sport and public health in times of COVID-19

Background

In February 2021 the “Cortina2021” Alpine World Ski Championships took place in the mountain town of Cortina d'Ampezzo (Italy), thus gaining the definition of “first sporting event of global significance in the time of covid-19 pandemic”. Though the event took place behind closed doors and in a context of national public health restrictive measures, it counted almost 6,000 participants.

Methods

A rigorous “Covid-19 Prevention and Hygiene Protocol” was drawn up by the local and regional health authorities together with the organizing committee, in order to contain the risk of viral circulation within the venue.

Results

Overall about 20,000 rapid antigen nasal swabs were performed to screen-detect sars-cov2 cases: only 22 of these were found positive, whereas 25 people were quarantined as close contacts.

Conclusions

The experience of “Cortina2021” proves that mass gatherings can take place even in times of epidemic threats, if adequately planned and by providing public health recommendations tailored on the viral circulation foreseen by the time the event is due. If new epidemics should arise in the future, hopefully the public health management of “Cortina2021” may be a template for next mass gatherings to be held, as far as possible, despite the viral circulation.

Paradoxical health care utilization patterns among children in Korea who did not receive mandatory pneumococcal vaccination

BACKGROUND

Unvaccinated children in the National Immunization Program (NIP) are a public health concern. We used Korean national population data to analyze health care utilization patterns of NIP-eligible children and identify the unvaccinated group.

METHODS

Pneumococcal vaccination (PCV) records were reviewed to determine the vaccination status of children born between 2013 and 2015. Children who received three doses or more from a 3 + 1 schedule were defined as vaccinated, while those who had not received any pneumococcal vaccinations were defined as unvaccinated. Corresponding health care utilization records were retrieved from the National Health Insurance Review and Assessment Service. The incidence of combined pneumococcal infections and health care utilization rates were estimated and the proportion of complementary and alternative medicine (CAM) utilization among the total health care utilization records was measured.

RESULTS

In total, 26,893 (2.1%) of 1,272,685 children remained unvaccinated. The incidence of pneumococcal infection was lower in unvaccinated children, at 10.1 cases (9.8-10.3) per 1000 person-months. However, their health care utilization was significantly lower than that noted for vaccinated children (hospital visit rate: 26.6 (95% confidence interval [CI] 26.5-26.7) vs. 3.2 (3.2-3.3) visits annually), indicating underdetection. CAM treatment was sought at least three times often more in unvaccinated children than in vaccinated children (3.5% vs. 1.1%).

CONCLUSION

Unvaccinated children showed significantly lower utilization of overall health care than the vaccinated children; however, a higher preference for CAM was noted among unvaccinated children than among vaccinated children. These differences in care-seeking patterns should be considered when identifying unvaccinated children and providing protection through vaccination programs.

Parental attitudes towards measles vaccination in the canton of Aargau, Switzerland: a latent class analysis

BACKGROUND

Despite the successes of routine national childhood vaccination programmes, measles remains a public health concern. The purpose of this paper is to investigate how patterns of parental attitudes are linked to the decision-making process for or against MMR vaccination. This exploratory study was designed to identify distinct patterns of attitudes towards or against measles vaccination through Latent Class Analysis (LCA) in a sub-sample of mothers living in the canton of Aargau in Switzerland.

METHODS

Parents of young children below 36 months of age were randomly selected through parents' counsellors' registries. Among other questions, respondents were asked to state their agreement in response to 14 belief statements regarding measles vaccination on a 5-point Likert scale. To identify groups of parents showing distinct patterns of attitudes and beliefs regarding measles vaccination, we used Latent Class Analysis (LCA).

RESULTS

The LCA showed three classes of parents with different attitudes and believes towards measles vaccination: The biggest group (class 1) are those having positive attitudes towards immunisation, followed by the second biggest group (class 2) which is characterised by having fearful attitudes and by showing uncertainty about immunisation. The third group (class 3) shows distinct patterns of critical attitudes against immunisation. Within this group over 90 % agree or totally agree that immunisation is an artificial intrusion into the natural immune system and therefore want to vaccinate their children only if necessary.

CONCLUSION

We find that parents in the Canton Aargau who hesitate to vaccinate their children against measles, mumps and rubella show distinct opinions and attitudes. Health professionals should be aware of these perceptions to tailor their messages accordingly and positively influence these parents to vaccinate their children. Special attention needs to be given to those parents who are planning to vaccinate their children but are not following the national guidelines.

Coupled disease-behavior dynamics on complex networks: A review

It is increasingly recognized that a key component of successful infection control efforts is understanding the complex, two-way interaction between disease dynamics and human behavioral and social dynamics. Human behavior such as contact precautions and social distancing clearly influence disease prevalence, but disease prevalence can in turn alter human behavior, forming a coupled, nonlinear system. Moreover, in many cases, the spatial structure of the population cannot be ignored, such that social and behavioral processes and/or transmission of infection must be represented with complex networks. Research on studying coupled disease-behavior dynamics in complex networks in particular is growing rapidly, and frequently makes use of analysis methods and concepts from statistical physics. Here, we review some of the growing literature in this area. We contrast network-based approaches to homogeneous-mixing approaches, point out how their predictions differ, and describe the rich and often surprising behavior of disease-behavior dynamics on complex networks, and compare them to processes in statistical physics. We discuss how these models can capture the dynamics that characterize many real-world scenarios, thereby suggesting ways that policy makers can better design effective prevention strategies. We also describe the growing sources of digital data that are facilitating research in this area. Finally, we suggest pitfalls which might be faced by researchers in the field, and we suggest several ways in which the field could move forward in the coming years.

The impact of imitation on vaccination behavior in social contact networks

Previous game-theoretic studies of vaccination behavior typically have often assumed that populations are homogeneously mixed and that individuals are fully rational. In reality, there is heterogeneity in the number of contacts per individual, and individuals tend to imitate others who appear to have adopted successful strategies. Here, we use network-based mathematical models to study the effects of both imitation behavior and contact heterogeneity on vaccination coverage and disease dynamics. We integrate contact network epidemiological models with a framework for decision-making, within which individuals make their decisions either based purely on payoff maximization or by imitating the vaccination behavior of a social contact. Simulations suggest that when the cost of vaccination is high imitation behavior may decrease vaccination coverage. However, when the cost of vaccination is small relative to that of infection, imitation behavior increases vaccination coverage, but, surprisingly, also increases the magnitude of epidemics through the clustering of non-vaccinators within the network. Thus, imitation behavior may impede the eradication of infectious diseases. Calculations that ignore behavioral clustering caused by imitation may significantly underestimate the levels of vaccination coverage required to attain herd immunity.

Both infectious diseases and behavioral traits can spread via social contacts. Using network-based mathematical models, our study addresses the interplay between these two processes, as disease spreads through a population and individuals copy their social contacts when making vaccination decisions. Imitation can produce clusters of non-vaccinating, susceptible individuals that facilitate relatively large outbreaks of infectious diseases despite high overall vaccination coverage. This may explain, for example, recent measles outbreaks observed in many countries with universal measles vaccination policies. Given that vaccine decisions are likely to be influenced by social contacts and that such imitation can have detrimental epidemiological effects, it is important that policy makers understand its causes, magnitude and implications for disease eradication.

The Swiss National Vaccination Coverage Survey, 2005-2007

OBJECTIVES

We described the results from the Swiss National Vaccination Coverage Survey (SNVCS) 2005-2007, a survey designed to monitor immunization coverage of children and adolescents residing in Switzerland in each canton within a three-year period.

METHODS

The SNVCS is a cross-sectional survey using a two-stage sampling design targeting children aged 2, 8, and 16 years. Families of selected children were contacted by mail and telephone. Coverage was determined via vaccination cards or vaccination summary forms.

RESULTS

A total of 25 out of 26 cantons participated in the survey, with 8,286 respondents for children aged 24-35 months, 10,314 respondents for children aged 8 years, and 9,301 respondents for teenagers aged 16 years. Compared with data from 1999-2003, coverage estimates for toddlers remained unchanged for diphtheria, tetanus, pertussis, poliomyelitis, and Haemophilus influenzae type b vaccines at three doses, but increased five percentage points to 86%-87% for measles-mumps-rubella at one dose and was 71% at two doses. Coverage for measles, mumps, and rubella were 89%-90% at one dose and 75% at two doses for 8-year-olds, and 94% and 76% for the two dosages, respectively, for 16-year-olds. Linguistic region and nationality were highly correlated with being vaccinated against measles for the two younger age groups.

CONCLUSION

Despite the increase in vaccine coverage, measles vaccination is still low, and the World Health Organization goal to eliminate measles by 2010 was not achieved in Switzerland. More efforts are needed by the cantons and the central government to increase vaccination coverage.

Molecular genotyping and epidemiology of measles virus transmission in the World Health Organization European Region, 2007-2009

BACKGROUND

In 2002, the World Health Organization (WHO) adopted a goal to eliminate measles in the European Region by 2010. Measles elimination is defined as the interruption of indigenous measles virus (MV) transmission. The molecular epidemiology of MV transmission in the WHO European Region was studied through the investigation of reported cases and outbreaks to monitor the region's progress toward its measles elimination goal.

METHODS

National and regional laboratories performed molecular characterization of MV detected between 2007 and 2009 in the WHO European Region. To document indigenous transmission and importations into the region, we analyzed genotyping results and epidemiological data on measles outbreaks reported by the member states.

RESULTS

Since 2007, MV genotype D6 has not been reported in the WHO European Region, suggesting that its chains of transmission have been interrupted, whereas several other MV genotypes are still circulating. Although several European countries have already interrupted indigenous MV transmission, genotyping showed that 3 endemic MV transmission chains have been reestablished in other countries.

CONCLUSIONS

The WHO European Region 2010 goal will not be met, as indigenous transmission of MV has not been interrupted. As the region begins to document its process of elimination verification to monitor progress toward the goal, countries will need to ensure that genotyping is performed in all measles outbreaks.

Measles transmission from an anthroposophic community to the general population, Germany 2008

BACKGROUND

In Germany, measles vaccination coverage with two doses is not yet sufficient to prevent regional outbreaks. Among the 16 German federal states, vaccination coverage was lowest in Bavaria with 85% in 2008. From March to mid-April 2008, four neighbouring Bavarian counties reported 55 measles-cases mostly linked to an ongoing measles outbreak in an anthroposophic school in Austria. We investigated this outbreak to guide future public health action.

METHODS

We applied the German national case-definition for measles and collected data using the national surveillance system and a questionnaire. Measles cases with disease onset a maximum of 18 days apart and spatial contact (e.g. same household, same school) were summed up in clusters. Two different interventions, which were implemented in schools and kindergartens in Bavaria, were compared by their impact on the size and duration of measles clusters. Susceptible persons were excluded from schools or kindergartens either with the first (intervention A) or second (intervention B) measles case occurring in the respective institution.

RESULTS

Among the 217 Bavarian measles cases identified from March-July 2008, 28 (13%) cases were attendees of the anthroposophic school in Austria. In total, vaccination status was known in 161 (74%) cases and 156 (97%) of them were not vaccinated. The main factor for non-vaccination was "fear of vaccine-related adverse events" (33%). Twenty-nine (18%) of 161 cases suffered complications. Exclusively genotype D5 was detected. Overall, 184 cases could be epidemiologically grouped into 59 clusters. Of those, 41 clusters could be linked to households and 13 to schools or kindergartens. The effect of intervention A and B was analysed in 10 school or kindergarten clusters. Depending on the respective intervention A or B, the median number of cases per cluster was 3 versus 13 (p = 0.05), and the median duration of a cluster was 3 versus 26 days (p = 0.13).

CONCLUSIONS

Introduction of measles virus into a pocket of susceptible persons (e.g. vaccination opponents or sceptics) may lead to large outbreaks in the general population, if the general population's vaccination coverage is below the WHO recommended level. Education on the safety of measles vaccine needs to be strengthened to increase measles vaccination coverage. Early intervention may limit spread in schools or kindergartens. Suspected measles has to be reported immediately to the local health authorities in order to allow intervention as early as possible.

Measles outbreak in a highly vaccinated population, San Diego, 2008: role of the intentionally undervaccinated

OBJECTIVE

In January 2008, an intentionally unvaccinated 7-year-old boy who was unknowingly infected with measles returned from Switzerland, resulting in the largest outbreak in San Diego, California, since 1991. We investigated the outbreak with the objective of understanding the effect of intentional undervaccination on measles transmission and its potential threat to measles elimination.

METHODS

We mapped vaccination-refusal rates according to school and school district, analyzed measles-transmission patterns, used discussion groups and network surveys to examine beliefs of parents who decline vaccination, and evaluated containment costs.

RESULTS

The importation resulted in 839 exposed persons, 11 additional cases (all in unvaccinated children), and the hospitalization of an infant too young to be vaccinated. Two-dose vaccination coverage of 95%, absence of vaccine failure, and a vigorous outbreak response halted spread beyond the third generation, at a net public-sector cost of $10 376 per case. Although 75% of the cases were of persons who were intentionally unvaccinated, 48 children too young to be vaccinated were quarantined, at an average family cost of $775 per child. Substantial rates of intentional undervaccination occurred in public charter and private schools, as well as public schools in upper-socioeconomic areas. Vaccine refusal clustered geographically and the overall rate seemed to be rising. In discussion groups and survey responses, the majority of parents who declined vaccination for their children were concerned with vaccine adverse events.

CONCLUSIONS

Despite high community vaccination coverage, measles outbreaks can occur among clusters of intentionally undervaccinated children, at major cost to public health agencies, medical systems, and families. Rising rates of intentional undervaccination can undermine measles elimination.

Measles outbreak linked to a minority group in Austria, 2008

We report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94·9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97·3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0·6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10–24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.

Willingness to vaccinate and to be vaccinated in adults

Vaccination may be mandated by regulation, as in some national infant vaccination programs, encouraged by health authorities, as in 'Flu vaccine campaigns for adults aged 60 years and older, or linked to the informed decision of individuals. Other methods include promotion by incentives to general practitioners, and recommendations from healthcare workers. All these factors contribute to variable vaccine coverage between countries and between different age and socio-economic groups. Many other factors, including providers' patient-oriented interventions and reimbursement issues play an important role in determining the level of vaccine uptake in a given population for a particular disease. However, the first step in vaccination campaigns is to give motivating information to healthcare workers that the benefits of being vaccinated outweigh possible inconvenience or adverse reactions. The information must be complete and accurate.When it has been ascertained that this information is understood and accepted, a system providing cheap and easy vaccination must be organised. Special groups such as the house-bound will need particular attention, appropriate information, and be included in free vaccination schemes. It should be acknowledged that social pressure often influences (positively or negatively) the decision of the individual. Lastly, a massive but objective information campaign is needed for the whole population, each and every visit to a health clinic being treated as an opportunity to check vaccination status and to vaccinate immediately if necessary. Simultaneous vaccination with two or more vaccines increases the chances of reaching the required population cover.

Life course vaccination and healthy aging

The authors notice the low vaccine coverage rate among European citizens and inventory the multiple reasons leading to the non-use of preventable infectious diseases vaccines in adults whose mortality consequences represent an important and unexpected burden of diseases. These facts are in close relation with the disruption of vaccine recommendations after the childhood vaccine program, the poor literacy knowledge concerning vaccines among the general population, but also unfortunately among physicians and other health care workers. Popular beliefs, fear of side-effects, fear of needles facilitated the constitution of active non-vaccine groups which conduct to the reappearance in non-vaccinated adults and with dramatic consequences of preventable childhood infectious diseases. This careful analysis of the current preventable infectious disease vaccine coverage in old adults leads to propose a life course vaccine programme including adult vaccinations as part of healthy aging as well as old adults' vaccine guidelines integrated in health prevention programs.

Networks of influence and infection: parental choices and childhood disease

Clusters of unvaccinated individuals are at risk of outbreaks of infection. When an individual's decision to choose vaccination is influenced by the choices of his social group, such clusters can readily arise. However, when the interactions that influence decision-making and those that permit the transmission of infection are different--for instance, when parents make vaccination decisions on behalf of their children--it is unclear how large the impact of this social influence will be. Here we use a modelling approach to represent social influence within a network of parents and the transmission of infection through a network of children. We show that the effect of social influence depends on the amount of overlap between the two different networks; large overlap means that clusters of parents who choose not to vaccinate are likely to have interacting children, generating clusters of unvaccinated children. Spatially local connections can further increase the impact of social influence. Outbreaks are most likely when parents who do not vaccinate have children who interact.

Measles in Europe: an epidemiological assessment

BACKGROUND

Measles persists in Europe despite the incorporation of the measles vaccine into routine childhood vaccination programmes more than 20 years ago. Our aim was therefore to review the epidemiology of measles in relation to the goal of elimination by 2010.

METHODS

National surveillance institutions from 32 European countries submitted data for 2006-07. Data for age-group, diagnosis confirmation, vaccination, hospital treatment, the presence of acute encephalitis as a complication of disease, and death were obtained. 30 countries also supplied data about importation of disease. Clinical, laboratory-confirmed, and epidemiologically linked cases that met the requirements for national surveillance were analysed. Cases were separated by age: younger than 1 year, 1-4 years, 5-9 years, 10-14 years, 15-19 years, and older than 20 years. Countries with indigenous measles incidence per 100 000 inhabitants per year of 0, less than 0.1, 0.1-1, and more than 1 were grouped into categories of zero, low, moderate, and high incidence, respectively.

FINDINGS

For the 2 years of the study, 12 132 cases of measles were recorded with most cases (n=10 329; 85%) from five countries: Romania, Germany, UK, Switzerland, and Italy. Most cases were unvaccinated or incompletely vaccinated children; however, almost a fifth were aged 20 years or older. For the same 2 years, seven measles-related deaths were recorded. High measles incidence in some European countries revealed suboptimum vaccination coverage. Of the 210 cases that were reported as being imported, 117 (56%) came from another country within Europe and 43 (20%) from Asia.

INTERPRETATION

The suboptimum vaccination coverage raises serious doubts that the goal of elimination by 2010 can be attained. Achievement and maintenance of optimum vaccination coverage and improved surveillance are the cornerstones of the measles elimination plan for Europe.

The effect of opinion clustering on disease outbreaks

Many high-income countries currently experience large outbreaks of vaccine-preventable diseases such as measles despite the availability of highly effective vaccines. This phenomenon lacks an explanation in countries where vaccination rates are rising on an already high level. Here, we build on the growing evidence that belief systems, rather than access to vaccines, are the primary barrier to vaccination in high-income countries, and show how a simple opinion formation process can lead to clusters of unvaccinated individuals, leading to a dramatic increase in disease outbreak probability. In particular, the effect of clustering on outbreak probabilities is strongest when the vaccination coverage is close to the level required to provide herd immunity under the assumption of random mixing. Our results based on computer simulations suggest that the current estimates of vaccination coverage necessary to avoid outbreaks of vaccine-preventable diseases might be too low.