The epidemiology of acute encephalitis.

Encephalitis means inflammation of the brain matter. Despite being a rare condition, encephalitis is of public health importance worldwide because it has high morbidity and mortality. Yet, many details about its epidemiology have yet to be elucidated. This review attempts to summarise what is known about the epidemiology of the infective causes of encephalitis and is based on a literature search of the Medline archives. Infection is the most common cause identified, with viruses being the most important known aetiological agents. Incidence varies between studies but is generally between 3.5 and 7.4 per 100,000 patient-years. Encephalitis affects peoples of all ages; however, incidence is higher in the paediatric population. Although both sexes are affected, most studies have shown a slight predominance in males. Encephalitis occurs worldwide; some aetiologies have a global distribution (herpesviruses) while others are geographically restricted (arboviruses). Although definite epidemiological trends are evident, it is difficult to make generalisations as few population-based studies exist, most cases are not reported to health authorities, and many possible pathogens are implicated but in most cases a cause is never found. A better understanding of the epidemiology of this devastating disease will pave the way for better prevention and control strategies

Human papilloma virus vaccination programs reduce health inequity in most scenarios: a simulation study

<p>Abstract</p> <p>Background</p> <p>The global and within-country epidemiology of cervical cancer exemplifies health inequity. Public health programs may reduce absolute risk but increase inequity; inequity may be further compounded by screening programs. In this context, we aimed to explore what the impact of human papillomavirus (HPV) vaccine might have on health equity allowing for uncertainty surrounding the long-term effect of HPV vaccination programs.</p> <p>Methods</p> <p>A simple static multi-way sensitivity analysis was carried out to compare the relative risk, comparing after to before implementation of a vaccination program, of infections which would cause invasive cervical cancer if neither prevented nor detected, using plausible ranges of vaccine effectiveness, vaccination coverage, screening sensitivity, screening uptake and changes in uptake.</p> <p>Results</p> <p>We considered a total number of 3,793,902 scenarios. In 63.9% of scenarios considered, vaccination would lead to a better outcome for a population or subgroup with that combination of parameters. Regardless of vaccine effectiveness and coverage, most simulations led to lower rates of disease.</p> <p>Conclusions</p> <p>If vaccination coverage and screening uptake are high, then communities are always better off with a vaccination program. The findings highlight the importance of achieving and maintaining high immunization coverage and screening uptake in high risk groups in the interest of health equity.</p

Approved but non-funded vaccines: Accessing individual protection

AbstractFunded immunization programs are best able to achieve high participation rates, optimal protection of the target population, and indirect protection of others. However, in many countries public funding of approved vaccines can be substantially delayed, limited to a portion of the at-risk population or denied altogether. In these situations, unfunded vaccines are often inaccessible to individuals at risk, allowing potentially avoidable morbidity and mortality to continue to occur. We contend that private access to approved but unfunded vaccines should be reconsidered and encouraged, with recognition that individuals have a prerogative to take advantage of a vaccine of potential benefit to them whether it is publicly funded or not. Moreover, numbers of “approved but unfunded” vaccines are likely to grow because governments will not be able to fund all future vaccines of potential benefit to some citizens. New strategies are needed to better use unfunded vaccines even though the net benefits will fall short of those of funded programs.Canada, after recent delays funding several new vaccine programs, has developed means to encourage private vaccine use. Physicians are required to inform relevant patients about risks and benefits of all recommended vaccines, publicly funded or not. Likewise, some provincial public health departments now recommend and promote both funded and unfunded vaccines. Pharmacists are key players in making unfunded vaccines locally available. Professional organizations are contributing to public and provider education about unfunded vaccines (e.g. herpes zoster, not funded in any province). Vaccine companies are gaining expertise with direct-to-consumer advertising. However, major challenges remain, such as making unfunded vaccines more available to low-income families and overcoming public expectations that all vaccines will be provided cost-free, when many other recommended personal preventive measures are user-pay. The greatest need is to change the widespread perception that approved vaccines should be publicly funded or ignored

Determining Mortality Rates Attributable to Clostridium difficile Infection

To determine accuracy of measures of deaths attributable to Clostridium difficile infection, we compared 3 measures for 2007–2008 in Ontario, Canada: death certificate; death within 30 days of infection; and panel review. Data on death within 30 days were more feasible than panel review and more accurate than death certificate data

Diphtheria in the Postepidemic Period, Europe, 2000–2009

Efforts must be made to maintain high vaccination coverage

Seroprevalence of Pandemic Influenza H1N1 in Ontario from January 2009–May 2010

We designed a seroprevalence study using multiple testing assays and population sources to estimate the community seroprevalence of pH1N1/09 and risk factors for infection before the outbreak was recognized and throughout the pandemic to the end of 2009/10 influenza season.Residual serum specimens from five time points (between 01/2009 and 05/2010) and samples from two time points from a prospectively recruited cohort were included. The distribution of risk factors was explored in multivariate adjusted analyses using logistic regression among the cohort. Antibody levels were measured by hemagglutination inhibition (HAI) and microneutralization (MN) assays.Residual sera from 3375 patients and 1024 prospectively recruited cohort participants were analyzed. Pre-pandemic seroprevalence ranged from 2%-12% across age groups. Overall seropositivity ranged from 10%-19% post-first wave and 32%-41% by the end of the 2009/10 influenza season. Seroprevalence and risk factors differed between MN and HAI assays, particularly in older age groups and between waves. Following the H1N1 vaccination program, higher GMT were noted among vaccinated individuals. Overall, 20-30% of the population was estimated to be infected.Combining population sources of sera across five time points with prospectively collected epidemiological information yielded a complete description of the evolution of pH1N1 infection

The effect of time since measles vaccination and age at first dose on measles vaccine effectiveness - A systematic review.

BACKGROUND: In settings where measles has been eliminated, vaccine-derived immunity may in theory wane more rapidly due to a lack of immune boosting by circulating measles virus. We aimed to assess whether measles vaccine effectiveness (VE) waned over time, and if so, whether differentially in measles-eliminated and measles-endemic settings. METHODS: We performed a systematic literature review of studies that reported VE and time since vaccination with measles-containing vaccine (MCV). We extracted information on case definition (clinical symptoms and/or laboratory diagnosis), method of vaccination status ascertainment (medical record or vaccine registry), as well as any biases which may have arisen from cold chain issues and a lack of an age at first dose of MCV. We then used linear regression to evaluate VE as a function of age at first dose of MCV and time since MCV. RESULTS: After screening 14,782 citations, we identified three full-text articles from measles-eliminated settings and 33 articles from measles-endemic settings. In elimination settings, two-dose VE estimates increased as age at first dose of MCV increased and decreased as time since MCV increased; however, the small number of studies available limited interpretation. In measles-endemic settings, one-dose VE increased by 1.5% (95% CI 0.5, 2.5) for every month increase in age at first dose of MCV. We found no evidence of waning VE in endemic settings. CONCLUSIONS: The paucity of data from measles-eliminated settings indicates that additional studies and approaches (such as studies using proxies including laboratory correlates of protection) are needed to answer the question of whether VE in measles-eliminated settings wanes. Age at first dose of MCV was the most important factor in determining VE. More VE studies need to be conducted in elimination settings, and standards should be developed for information collected and reported in such studies

Effectiveness of AS03 adjuvanted pandemic H1N1 vaccine: case-control evaluation based on sentinel surveillance system in Canada, autumn 2009

Objective To assess the effectiveness of the pandemic influenza A/H1N1 vaccine used in Canada during autumn 2009

Pandemic H1N1 in Canada and the use of evidence in developing public health policies e A policy analysis

a b s t r a c t When responding to a novel infectious disease outbreak, policies are set under time constraints and uncertainty which can limit the ability to control the outbreak and result in unintended consequences including lack of public confidence. The H1N1 pandemic highlighted challenges in public health decision-making during a public health emergency. Understanding this process to identify barriers and modifiable influences is important to improve the response to future emergencies. The purpose of this study is to examine the H1N1 pandemic decision-making process in Canada with an emphasis on the use of evidence for public health decisions. Using semi-structured key informant interviews conducted after the pandemic (JulyeNovember 2010) and a document analysis, we examined four highly debated pandemic policies: use of adjuvanted vaccine by pregnant women, vaccine priority groups and sequencing, school closures and personal protective equipment. Data were analysed for thematic content guided by Lomas&apos; policy decision-making framework as well as indicative coding using iterative methods. We interviewed 40 public health officials and scientific advisors across Canada and reviewed 76 pandemic policy documents. Our analysis revealed that pandemic pre-planning resulted in strong beliefs, which defined the decision-making process. Existing ideological perspectives of evidence strongly influenced how information was used such that the same evidentiary sources were interpreted differently according to the ideological perspective. Participants recognized that current models for public health decision-making failed to make explicit the roles of scientific evidence in relation to contextual factors. Conflict avoidance theory explained policy decisions that went against the prevailing evidence. Clarification of roles and responsibilities within the public health system would reduce duplication and maintain credibility. A more transparent and iterative approach to incorporating evidence into public health decision-making that reflects the realities of the external pressures present during a public health emergency is needed