Children hospitalised with four common viral diseases showed epidemiological differences but few socio-economic variations.

AIM: This study explored the differences in demographic and socio-economic factors between children hospitalised due to four common viral infections. METHODS: Demographic data were obtained from Statistics Sweden on >3000 children admitted to Astrid Lindgren Children's Hospital in 2009-2014 with rotavirus, influenza, respiratory syncytial virus (RSV) or chickenpox. We compared demographic and socio-economic 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 socio-economic 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.

Validity of International Health Regulations in reporting emerging infectious diseases.

Understanding which emerging infectious diseases are of international public health concern is vital. The International Health Regulations include a decision instrument to help countries determine which public health events are of international concern and require reporting to the World Health Organization (WHO) on the basis of seriousness, unusualness, international spread and trade, or need for travel restrictions. This study examined the validity of the International Health Regulations decision instrument in reporting emerging infectious disease to WHO by calculating its sensitivity, specificity, and positive predictive value. It found a sensitivity of 95.6%, a specificity of 38%, and a positive predictive value of 35.5%. These findings are acceptable if the notification volume to WHO remains low. Validity could be improved by setting more prescriptive criteria of seriousness and unusualness and training persons responsible for notification. However, the criteria should be balanced with the need for the instrument to adapt to future unknown threats.

Some model based considerations on observing generation times for communicable diseases.

The generation time of an infectious disease is usually defined as the time from the moment one person becomes infected until that person infects another person. The concept is similar to "generation gap" in demography, with new infections replacing births in a population. Originally applied to diseases such as measles where at least the first generations are clearly discernible, the concept has recently been extended to other diseases, such as influenza, where time order of infections is usually much less apparent. By formulating the relevant statistical questions within a simple yet basic mathematical model for infection spread, it is possible to derive theoretical properties of observations in various situations e.g. in "isolation", in households, or during large outbreaks. In each case, it is shown that the sampling distribution of observations depends on a number of factors, usually not considered in the literature and that must be taken into account in order to achieve unbiased inference about the generation time distribution. Some implications of these findings for statistical inference methods in epidemic spread models are discussed.

Intervening to reduce inequalities in infections in Europe.

The European Centre for Disease Prevention and Control was founded in response to newly emerging infections such as severe acute respiratory syndrome and avian influenza. However, Europe faces other communicable disease challenges that have proven to be remarkably resilient to public health interventions. We present examples of communicable diseases with inequitable distribution among those with poor educational attainment, low income, or other socioeconomic factors in every European country. Because these findings are incompatible with social justice and fairness, we examine strategic interventions targeting upstream causes of communicable disease transmission keeping in mind 10 indispensable public health functions essential to reach marginalized groups. These interventions have to be tailored to the socio-political context and rely on community-based decision-making and intersectorial collaboration.

Timeliness of MMR vaccination--influence on vaccination coverage.

Over the last seven years, and especially in 2001, a declining coverage for MMR vaccination in 2-year-olds has been noted in Sweden. By recording actual date of vaccination in a cohort of almost 4,000 children in a county in central Sweden, we found that parents' decision to postpone vaccination by up to 1.5 years beyond the stipulated age of 18 months accounted for about half the reported drop in 2001. Even if coverage thus improves with time, postponed vaccination adds to the pool of unprotected children in the population. The design of the current national surveillance system overestimates coverage at 2 years and fails to record delayed vaccination. To avoid future outbreaks that can appear around imported cases of measles it is crucial to attain high coverage levels by timely vaccination.