I am passionate about science and think that vaccines are a great solution to fight diseases
Vaccinated people help build 'herd immunity' to protect those who can't get immunised themselves
In 2017, a vegan mum, who was forced to vaccinate her children, made it to the news. According to the Independent: '...(the judge) upheld the decision that the children should be vaccinated under the terms of the 1989 Children’s Act, which allows courts to overrule a parent for the welfare of the child...'
But why is it so important that children get vaccinated, despite opposition from parents? Immunisations prevent illnesses, disabilities and even death from diseases such as cervical cancer, diphtheria, hepatitis B, measles, mumps, pertussis (whooping cough), pneumonia, polio, rotavirus diarrhoea, rubella and tetanus. Globalisation means exposure to more pathogens more frequently.
Vaccinations help the immune system to fight a pathogen more effectively. In a lot of cases once an individual is exposed to a certain bacterium or virus they acquire immunity. This means that should the same pathogen appear again it will be eradicated much more quickly.
Once a critical number of people living in the same community are immunised against a contagious disease, a so-called 'herd' or 'community immunity' is build. This protects those who cannot receive certain vaccines, e.g. infants, pregnant women and immunocompromised individuals.
How effective is global immunisation? According to the WHO there are currently an estimated 2 to 3 million deaths per year avoided as a result of an increase in the uptake of new and underused vaccines. Additionally to this, 1.5 million more deaths could be avoided, if the global coverage of vaccinations would further improve.
Abstract: Uptake rates for the combined measles, mumps and rubella (MMR) vaccine have been below the required 95% in the UK since a retracted and discredited article linking the MMR vaccine with autism and inflammatory bowel disease was released in 1998. This study undertook semi-structured telephone interviews among parents or carers of 47 unvaccinated measles cases who were aged between 13 months and 9 years, during a large measles outbreak in Merseyside. Results showed that concerns over the specific links with autism remain an important cause of refusal to vaccinate, with over half of respondents stating this as a reason. A quarter stated child illness during scheduled vaccination time, while other reasons included general safety concerns and access issues. Over half of respondents felt that more information or a discussion with a health professional would help the decision-making process, while a third stated improved access. There was clear support for vaccination among respondents when asked about current opinions regarding MMR vaccine. The findings support the hypothesis that safety concerns remain a major barrier to MMR vaccination, and also support previous evidence that experience of measles is an important determinant in the decision to vaccinate.
Pub.: 13 Aug '15, Pinned: 13 Apr '17
Abstract: Routinely, the first measles, mumps, and rubella (MMR) vaccine dose is given at 14 months of age in the Netherlands. However, during a measles epidemic in 2013-2014, MMR vaccination was also offered to 6-14-month-olds in municipalities with <90% MMR vaccination coverage. We studied the effectiveness of the early MMR vaccination schedule.Parents of all infants targeted for early MMR vaccination were asked to participate. When parent(s) suspected measles, their infant's saliva was tested for measles-specific antibodies. The vaccine effectiveness (VE) against laboratory-confirmed and self-reported measles was estimated using Cox regression, with VE calculated as 1 minus the hazard ratio.Three vaccinated and 10 unvaccinated laboratory-confirmed cases occurred over observation times of 106631 and 23769 days, respectively. The unadjusted VE against laboratory-confirmed measles was 94% (95% confidence interval [CI], 79%-98%). After adjustment for religion and sibling's vaccination status, the VE decreased to 71% (-72%-95%). For self-reported measles, the unadjusted and adjusted VE was 67% (40%-82%) and 43% (-12%-71%), respectively.Infants vaccinated between 6 and 14 months of age had a lower risk of measles than unvaccinated infants. However, part of the effect was caused by herd immunity, since vaccinated infants were more likely to be surrounded by other vaccinated individuals.
Pub.: 04 Apr '17, Pinned: 10 Apr '17
Abstract: Preventing pneumonia in the elderly and study participants individuals with comorbidities is an unmet clinical need. Streptococcus pneumoniae is the commonest bacterial cause of pneumonia, and we summarize recent findings regarding current S. pneumoniae vaccines, and debate their efficacy and cost-effectiveness in risk groups. We also discuss potential future vaccine strategies such as protein antigen vaccines.Current vaccination with pneumococcal polysaccharide vaccine does not prevent S. pneumoniae pneumonia. Vaccination with pneumococcal conjugated vaccine (PCV) prevents nasopharyngeal colonization, but although PCV13 has recently been shown to prevent S. pneumoniae pneumonia in adults, its overall efficacy was relatively low. The results of cost-effectiveness studies of PCV vaccination in adults are variable with some showing this is a cost-effective strategy, whereas others have not. The lack of cost-effectiveness is predominantly because of the current cost of the PCV vaccine and the existing herd immunity effect from childhood PCV vaccination on vaccine serotypes.S. pneumoniae pneumonia is a vaccine-preventable disease but remains a common cause of morbidity and mortality. Advances in vaccination using approaches that induce serotypes-independent immunity and are immunogenic in high-risk groups are required to reduce the burden of disease because of S. pneumoniae.
Pub.: 16 Feb '17, Pinned: 10 Apr '17
Abstract: This study was a cross-sectional case-control study aimed at (1) identifying risk factors contributing to the measles epidemic and (2) evaluating the impacts of measles-containing vaccines (MCVs), with the goal of providing evidence-based recommendations for measles elimination strategies in China. Data on measles cases from 2000 to 2014 were obtained from a passive surveillance system at the Center for Diseases Prevention and Control in Xianyang. The effectiveness of MCVs was evaluated in 357 patients with a vaccination history and 503 healthy randomly selected controls. Patient data were subjected to multivariable logistic regression modeling. From 2005 to 2014, the average incidence of measles in Xianyang was 5.42 cases per 100,000 people. The second MCV dose was highly protective in 8-month-old infants. MCVs in general have been highly protective in 8-month-old infants. Multivariable logistic regression modeling indicated that age (≥2 years vs. <2years), MCV dose 2 vaccination, and MV vaccination were each independently associated with measles case status. In conclusions: A MCV should be administered on time to all age-eligible children, reproductive-age women, and migrant populations, to maximize herd immunity to measles.
Pub.: 04 Mar '17, Pinned: 10 Apr '17
Abstract: People with diabetes are at a higher risk of influenza infections and severe complications. The vaccination of close contacts could offer indirect protection to people with diabetes; this is known as "herd immunity." The aim of this study is to investigate the vaccination rates of people with diabetes and their household contacts in Hong Kong.Face-to-face interviews with 158 patients diagnosed with Type 2 diabetes and aged ⩾65years were conducted in clinics. Telephone interviews were then conducted with 281 adult household contacts.Seasonal influenza vaccination rates were 54.5% and 27.4%, in people with diabetes and their contacts, respectively. The vaccination status of patients was not significantly associated with the vaccination of their household contacts (p=0.073). Among household contacts, children or the elderly, the partners or couples of patients, and those with more hours of daily contact, or with chronic conditions, were associated with higher vaccination rates. However, only age remained significant after adjusting for confounding factors in logistic regression models.The low vaccination rates of people with diabetes and their close contacts highlight the need to promote vaccination in susceptible populations and to educate the public about herd immunity.
Pub.: 18 Jan '17, Pinned: 10 Apr '17
Abstract: Vaccine delay and refusal present very real threats to public health. Since even a slight reduction in vaccination rates could produce major consequences as herd immunity is eroded, it is imperative to understand the factors that contribute to decision-making about vaccines. Recent scholarship on the concept of "vaccine hesitancy" emphasizes that vaccine behaviors and beliefs tend to fall along a continuum from refusal to acceptance. Most research on hesitancy has focused on parental decision-making about childhood vaccines, but could be extended to explore decision-making related to adult immunization against seasonal influenza. In particular, vaccine hesitancy could be a useful approach to understand the persistence of racial/ethnic disparities between African American and White adults. This study relied on a thematic content analysis of qualitative data, including 12 semi-structured interviews, 9 focus groups (N=90), and 16 in-depth interviews, for a total sample of 118 (N=118) African American and White adults. All data were transcribed and analyzed with Atlas.ti. A coding scheme combining both inductive and deductive codes was utilized to identify themes related to vaccine hesitancy. The study found a continuum of vaccine behavior from never-takers, sometimes-takers, and always-takers, with significant differences between African Americans and Whites. We compared our findings to the Three Cs: Complacency, Convenience, and Confidence framework. Complacency contributed to low vaccine acceptance with both races. Among sometimes-takers and always-takers, convenience was often cited as a reason for their behavior, while never-takers of both races were more likely to describe other reasons for non-vaccination, with convenience only a secondary explanation. However, for African Americans, cost was a barrier. There were racial differences in trust and confidence that impacted the decision-making process. The framework, though not a natural fit for the data, does provide some insight into the differential sources of hesitancy between these two populations. Complacency and confidence clearly impact vaccine behavior, often more profoundly than convenience, which can contribute either negatively or positively to vaccine acceptance. The Three Cs framework is a useful, but limited tool to understanding racial disparities. Understanding the distinctions in those cultural factors that drive lower vaccine confidence and greater hesitancy among African Americans could lead to more effective communication strategies as well as changes in the delivery of vaccines to increase convenience and passive acceptance.
Pub.: 28 Feb '17, Pinned: 10 Apr '17
Abstract: Despite relatively high national vaccination coverage for measles, geographic vaccination variation exists resulting in clusters of susceptibility. A portion of this geographic variation can be explained by differences in state policies related to non-medical vaccine exemptions. The objective of this analysis was to determine the magnitude, likelihood, and cost of a measles outbreak under different non-medical vaccine exemption policies.An agent-based transmission model simulated the likelihood and magnitude of a measles outbreak under different non-medical vaccine exemption policies, previously categorized as easy, medium, or difficult. The model accounted for measles herd immunity, infectiousness of the pathogen, vaccine efficacy, duration of incubation and communicable periods, acquired natural immunity, and the rate of recovery. Public health contact tracing was also modeled. Model outcomes, including the number of secondary cases, hospitalizations, and deaths, were monetized to determine the economic burden of the simulated outbreaks.A state with easy non-medical vaccine exemption policies is 140% and 190% more likely to experience a measles outbreak compared to states with medium or difficult policies, respectively. The magnitude of these outbreaks can be reduced by half by strengthening exemption policies. These declines are associated with significant cost reductions to public health, the healthcare system, and the individual.Strengthening non-medical vaccine exemption policies is one mechanism to increase vaccination coverage to reduce the health and economic impact of a measles outbreak. States exploring options for decreasing their vulnerability to outbreaks of vaccine preventable diseases should consider more stringent requirements for non-medical vaccine exemptions.
Pub.: 14 Mar '17, Pinned: 10 Apr '17
Abstract: In the late 1990s, in the context of renewed concerns of an influenza pandemic, countries such as Ghana and Malawi established plans for the deployment of vaccines and vaccination strategies. A new pandemic was declared in mid-June 2009, and by April 2011, Ghana and Malawi vaccinated 10% of the population. We examine the public health policy perspectives on vaccination as a means to prevent the spread of infection under post pandemic conditions.In-depth interviews were conducted with 46 policymakers (Ghana, n = 24; Malawi, n = 22), identified through snowballing sampling. Interviews were supplemented by field notes and the analysis of policy documents.The use of vaccination to interrupt the pandemic influenza was affected by delays in the procurement, delivery and administration of vaccines, suboptimal vaccination coverage, refusals to be vaccinated, and the politics behind vaccination strategies. More generally, rolling-out of vaccination after the transmission of the influenza virus had abated was influenced by policymakers' own financial incentives, and government and foreign policy conditionality on vaccination. This led to confusion about targeting and coverage, with many policymakers justifying that the vaccination of 10% of the population would establish herd immunity and so reduce future risk. Ghana succeeded in vaccinating 2.3 million of the select groups (100% coverage), while Malawi, despite recourse to force, succeeded only in vaccinating 1.15 million (74% coverage of select groups). For most policymakers, vaccination coverage was perceived as successful, despite that vaccination delays and coverage would not have prevented infection when influenza was at its peak.While the vaccination strategy was problematic and implemented too late to reduce the effects of the 2009 epidemic, policy makers supported the overall goal of pandemic influenza vaccination to interrupt infection. In this context, there was strong support for governments engaging in contracts with pharmaceutical companies to ensure the timely supply of vaccines, and developing well-defined guidelines to address vaccination delays, refusals and coverage.
Pub.: 02 Mar '17, Pinned: 10 Apr '17
Abstract: Social interactions make communicable disease a core concern of public health policy. A prevalent problem is scarcity of empirical evidence informative about how interventions affect illness. Randomized trials, which have been important to evaluation of treatments for noninfectious diseases, are less informative about treatment of communicable diseases because they do not fully reveal the indirect preventive (herd immunity) effect of vaccination on persons who are not vaccinated or are unsuccessfully vaccinated. This paper studies the decision problem faced by a health planner who observes the illness rate that occurs when persons make decentralized vaccination choices and who contemplates whether to mandate vaccination. The planner's objective is to minimize the social cost of illness and vaccination. Uncertainty about the magnitude of the indirect effect of vaccination implies uncertainty about the illness rate that a mandate would yield. I first study a simple representative-agent setting and derive conditions under which the planner can determine whether mandating vaccination is optimal. When optimal policy is indeterminate, I juxtapose several criteria for decision making—expected utility, minimax, and minimax-regret—and compare the policies they generate. I then extend the analysis to a more general setting in which members of the population may have heterogenous attributes.I have benefitted from the opportunity to present this work in seminars at the Booth School of Business, University of Chicago, the Department of Economics, University of California at Santa Barbara, and the Schaeffer Center for Health Policy and Economics, University of Southern California. I have also benefitted from the comments of an anonymous reviewer and associate editor.
Pub.: 07 Feb '17, Pinned: 10 Apr '17
Abstract: Parental concerns about vaccine safety have grown in the United States and abroad, resulting in delayed or skipped immunizations (often called "vaccine hesitancy"). To address vaccine hesitancy in Washington State, a public-private partnership of health organizations implemented and evaluated a 3-year community intervention, called the "Immunity Community." The intervention mobilized parents who value immunization and provided them with tools to engage in positive dialogue about immunizations in their communities. The evaluation used qualitative and quantitative methods, including focus groups, interviews, and pre and post online surveys of parents, to assess perceptions about and reactions to the intervention, assess facilitators and barriers to success, and track outcomes including parental knowledge and attitudes. The program successfully engaged parent volunteers to be immunization advocates. Surveys of parents in the intervention communities showed statistically significant improvements in vaccine-related attitudes: The percentage concerned about other parents not vaccinating their children increased from 81.2% to 88.6%, and the percentage reporting themselves as "vaccine-hesitant" decreased from 22.6% to 14.0%. There were not statistically significant changes in parental behaviors. This study demonstrates the promise of using parent advocates as part of a community-based approach to reduce vaccine hesitancy.
Pub.: 12 Apr '17, Pinned: 13 Apr '17
Abstract: Parents are often uncertain about the vaccination status of their children. In times of vaccine hesitancy, vaccination programs could benefit from active patient participation. The Vaccination App (VAccApp) was developed by the Vienna Vaccine Safety Initiative, enabling parents to learn about the vaccination status of their children, including 25 different routine, special indication and travel vaccines listed in the WHO Immunization Certificate of Vaccination (WHO-ICV). Between 2012 and 2014, the VAccApp was validated in a hospital-based quality management program in Berlin, Germany, in collaboration with the Robert Koch Institute. Parents of 178 children were asked to transfer the immunization data of their children from the WHO-ICV into the VAccApp. The respective WHO-ICV was photocopied for independent, professional data entry (gold standard). Demonstrating the status quo in vaccine information reporting, a Recall Group of 278 parents underwent structured interviews for verbal immunization histories, without the respective WHO-ICV. Only 9% of the Recall Group were able to provide a complete vaccination status; on average 39% of the questions were answered correctly. Using the WHO-ICV with the help of the VAccApp resulted in 62% of parents providing a complete vaccination status; on average 95% of the questions were answered correctly. After using the VAccApp, parents were more likely to remember key aspects of the vaccination history. User-friendly mobile applications empower parents to take a closer look at the vaccination record, thereby taking an active role in providing accurate vaccination histories. Parents may become motivated to ask informed questions and to keep vaccinations up-to-date.
Pub.: 14 Jan '17, Pinned: 13 Apr '17