Search

For decades, assessments of the impact of universal varicella vaccination on the epidemiology of varicella and herpes zoster (HZ) have been made using mathematical modelling. Decreased virus circulation and the resulting diminished exogenous boosting have been predicted to lead to a surge in HZ incidence. Lately, the exogenous boosting hypothesis has been challenged due to a lack of an extensive surge in HZ incidence in countries with, by now long-standing universal varicella vaccination.In a deterministic compartmental transmission model of varicella zoster virus disease, we model various levels and duration of protection from boosting to explore the impact of successful childhood varicella vaccination on HZ incidence.Considering total HZ incidence, lifelong and strong protection from boosting give a stable incidence of HZ for about 60 years followed by a decline, whereas lifelong intermediate protection leads to a decline. So does weak protection of intermediate duration. Full and short protection, lead to a small surge, while full and intermediate protection lead to the largest HZ surge. HZ incidence by age group show that total incidence is the result of opposing increasing and decreasing trends in the various age groups over time.The absence of an extensive surge in HZ incidence after varicella vaccination can, especially during the first 20-30 years, occur in either strong, intermediate or weak boosting scenarios. The impact seems to depend on an interplay of the protective level and duration of the protection in determining the basic reactivation rate and the proportion of the population that is susceptible at the start of vaccination. However, the picture depends on whether the entire population or specific age groups are observed.

Aim This study explored the differences in demographic and socioeconomic factors between children hospitalised due to four common viral infections. Methods Demographic data were obtained from Statistics Sweden on >3,000 children admitted to Astrid Lindgren Children's Hospital in 2009-2014 with rotavirus, influenza, respiratory syncytial virus (RSV), or chickenpox. We compared demographic and socioeconomic factors between case groups using logistic regression with rotavirus cases as reference. Results There were differences in the median age at admission; RSV cases were younger (0.4 years), influenza (2.4 years) and chickenpox cases (2.7 years) older than rotavirus cases (1.2 years). RSV, influenza and chickenpox cases lived in families with more children than rotavirus cases. RSV and influenza cases were more likely to have underlying chronic conditions. Mothers of RSV cases were more likely to be born in Sweden. Further socioeconomic differences were not robustly confirmed in sensitivity analyses. Conclusion We found a few differences in demographic factors between children hospitalised with the four common infections, which were mainly explained by the epidemiology and transmission patterns of these infections.

Objectives Comprehensive cost-effectiveness analyses of introducing varicella and/or herpes zoster vaccination in the Swedish national vaccination programme. Design Cost-effectiveness analyses based on epidemiological results from a specifically developed transmission model. Setting National vaccination programme in Sweden, over an 85- or 20-year time horizon depending on the vaccination strategy. Participants Hypothetical cohorts of people aged 12 months and 65-years at baseline. Interventions Four alternative vaccination strategies; 1, not to vaccinate; 2, varicella vaccination with one dose of the live attenuated vaccine at age 12 months and a second dose at age 18 months; 3, herpes zoster vaccination with one dose of the live attenuated vaccine at 65 years of age; and 4, both vaccine against varicella and herpes zoster with the before-mentioned strategies. Main outcome measures Accumulated cost and quality-adjusted life years (QALY) for each strategy, and incremental cost-effectiveness ratios (ICER). Results It would be cost-effective to vaccinate against varicella (dominant), but not to vaccinate against herpes zoster (ICER of EUR 200,000), assuming a cost-effectiveness threshold of EUR 50,000 per QALY. The incremental analysis between varicella vaccination only and the combined programme results in a cost per gained QALY of almost EUR 1.6 million. Conclusions The results from this study are central components for policy-relevant decision-making, and suggest that it was cost-effective to introduce varicella vaccination in Sweden, whereas herpes zoster vaccination with the live attenuated vaccine for the elderly was not cost-effective–the health effects of the latter vaccination cannot be considered reasonable in relation to its costs. Future observational and surveillance studies are needed to make reasonable predictions on how boosting affects the herpes zoster incidence in the population, and thus the cost-effectiveness of a vaccination programme against varicella. Also, the link between herpes zoster and sequelae need to be studied in more detail to include it suitably in health economic evaluations.

Background and aims: Sharing of unsterile injection equipment contributes to transmission of hepatitis C virus (HCV), HIV and hepatitis B virus (HBV) among people who inject drugs (PWID) but is lar...

Background Chickenpox vaccine is not included in the routine childhood vaccination programme in Sweden. The aim of this study was to estimate the baseline of national chickenpox disease burden, as comprehensive studies, required for an assessment regarding vaccine introduction, are lacking. Methods We used available health care registers and databases; the death register, hospitalisations register, communicable disease notifications database, Stockholm County registers on consultations in specialist and primary care, temporary parental benefit to care for a sick child, and searches on the health care system’s website. From each data source, records regarding chickenpox were identified and extracted, either using relevant diagnosis codes (ICD-10) or key words. A descriptive analysis with regards to number of cases and incidence, severity, and seasonality, was carried out covering the time period 2007 to 2013. Results There were on average 333 patients hospitalised annually due to chickenpox, yielding a hospitalisation rate of 3.56/100,000 person-years. We found a slight male predominance in hospitalised cases. The highest hospitalisation rate was seen in 1 year-olds, whereas the peak in primary care consultations was in 2 year-olds. Nearly a quarter of children had parents who reported absence from work to care for them when sick with chickenpox. The average yearly death rate from chickenpox was 0.034/100,000 person-years. The duration of hospital stay increased with age. The seasonality in number of searches on the health care website corresponded well with hospitalisations and primary care consultations with peaks in spring. Conclusions This study shows chickenpox death and hospitalisation rates in range with other European countries without routine vaccination. Swedish children fall ill with chickenpox at a very young age. The study provides essential input for future discussions on the introduction of routine chickenpox vaccination in Sweden.

Background Early diagnosis of HIV is important for the prognosis of individual patients, because antiretroviral treatment can be started at the appropriate time, and for public health, because transmission can be prevented. Methods Data were collected from 767 HIV patients who were diagnosed in Sweden during 2003–2010 and were infected in Sweden or born in Sweden and infected abroad. A recent infection testing algorithm (RITA) was applied to BED-EIA test results (OD-n < 0.8), CD4 counts (≥ 200 cells/μl), and clinical information. A recent infection classification was used as indicator for early diagnosis. Time trends in early diagnosis were investigated to detect population changes in HIV testing behavior. Patients with early diagnosis were compared to patients with delayed diagnosis with respect to age, gender, transmission route, and country of infection (Sweden or abroad). Results Early diagnosis was observed in 271 patients (35%). There was no statistically significant time trend in the yearly percentage of patients with early diagnosis in the entire study group (p = 0.836) or in subgroups. Early diagnosis was significantly more common in men who have sex men (MSM) (45%) than in heterosexuals (21%) and injecting drug users (27%) (p < 0.001 and p = 0.001, respectively) in both univariate and multivariable analyses. The only other factor that remained associated with early diagnosis in multivariable analysis was young age group. Conclusion Approximately one-third of the study patients were diagnosed early with no significant change over time. Delayed HIV diagnosis is a considerable problem in Sweden, which does not appear to diminish.

The modern medical treatment of HIV with antiretroviral therapy (ART) has drastically reduced the morbidity and mortality in patients infected with this virus. ART has also been shown to reduce the transmission risk from individual patients as well as the spread of the infection at the population level. This position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy is based on a workshop organized in the fall of 2012. It summarizes the latest research and knowledge on the risk of HIV transmission from patients on ART, with a focus on the risk of sexual transmission. The risk of transmission via shared injection equipment among intravenous drug users is also examined, as is the risk of mother-to-child transmission. Based on current knowledge, the risk of transmission through vaginal or anal intercourse involving the use of a condom has been judged to be minimal, provided that the person infected with HIV fulfils the criteria for effective ART. This probably also applies to unprotected intercourse, provided that no other sexually transmitted infections are present, although it is not currently possible to fully support this conclusion with direct scientific evidence. ART is judged to markedly reduce the risk of blood-borne transmission between people who share injection equipment. Finally, the risk of transmission from mother to child is very low, provided that ART is started well in advance of delivery.

Background Persistent infection with human papillomavirus (HPV) is a prerequisite for cervical cancer, which causes 175 yearly deaths and substantial morbidity in Denmark. In January 2009, HPV-vaccination for 12 year-old girls was introduced into the free-of-charge childhood vaccination programme. Due to concerns about potential poor compliance we determined the uptake and identified determinants for vaccination after the first year of the programme. Methods All vaccinations given within the vaccination programme are reported to a central register, which we linked to demographic information found in the Danish civil register. We calculated vaccination uptake and used Cox regression survival analysis to compare the uptake rates between demographic subgroups in the population, e.g. by number of siblings, age of mother (at the daughter's birth) and place of origin. Results The uptake among the 33,838 eligible girls was 80%, 75% and 62% respectively for the three HPV-doses. All subgroups had uptake above 68% for the first HPV-vaccination. Girls with mothers younger or older than the reference group of 25–34 years had a lower uptake rate (adjHR 0.94, 95% CI 0.91–0.97 and adjHR 0.91, 95% CI 0.88–0.94 respectively). Girls with 5 or more siblings had lower uptake rate than girls without siblings (adjHR 0.79, 95% CI 0.71–0.87). Girls born in other EU/EFTA-countries had lower uptake rate than Danish-born girls with Danish-born parents (adjHR 0.74, 95% CI 0.67–0.82). Conclusions The introduction of routine HPV-vaccination in Denmark resulted in a relatively high uptake, indicating little reason for major concern about barriers towards the vaccination in Denmark. Population groups with reduced uptake were identified, but as they were small in number their effect on the overall vaccination coverage was marginal. Nonetheless, these groups should be targeted in future acceptance studies and vaccination awareness campaigns.

In November 2010, approximate to 27,000 (approximate to 45%) inhabitants of Östersund, Sweden, were affected by a waterborne outbreak of cryptosporidiosis. The outbreak was characterized by a rapid onset and high attack rate, especially among young and middle-aged persons. Young age, number of infected family members, amount of water consumed daily, and gluten intolerance were identified as risk factors for acquiring cryptosporidiosis. Also, chronic intestinal disease and young age were significantly associated with prolonged diarrhea. Identification of Ctyptosporidium hominis subtype lbA10G2 in human and environmental samples and consistently low numbers of oocysts in drinking water confirmed insufficient reduction of parasites by the municipal water treatment plant. The current outbreak shows that use of inadequate microbial barriers at water treatment plants can have serious consequences for public health. This risk can be minimized by optimizing control of raw water quality and employing multiple barriers that remove or inactivate all groups of pathogens.

We analysed Danish surveillance data to estimate influenza-associated morbidity and mortality in 2009. To obtain population-based estimates of the clinical attack rate, we combined data from two different primary health care surveillance systems, national numbers of the proportion of positive influenza tests, and data from a web-based interview on health care seeking behaviour during the pandemic. From a national registry, we obtained data on hospital admissions (ICD-10 codes) for influenza related conditions. Admission to intensive care was monitored by a dedicated surveillance scheme. Mortality was estimated among laboratory confirmed cases but was also expressed as excess all-cause mortality attributed to influenza-like illness in a multivariable time series analysis. In total, we estimated that 274,000 individuals (5%) in Denmark experienced clinical illness. The highest attack rate was found in children 5–14 years (15%). Compared with the expected number of hospital admissions, there was an 80% increase in number of influenza related hospital admissions in this age group. The numbers of patients admitted to intensive care approached 5% of the national capacity. Estimates of the number of deaths ranged from 30 to 312 (0.5–5.7 per 100,000 population) depending on the methodology. In conclusion, the pandemic was characterised by high morbidity and unprecedented high rates of admissions to hospitals for a range of influenza-related conditions affecting mainly children. Nonetheless, the burden of illness was lower than assumed in planning scenarios, and the present pandemic compares favourable with the 20th century pandemics.