The relative importance of frequency of contacts and duration of exposure for the spread of directly transmitted infections.

The recent availability of survey data on social contact patterns has made possible important advances in the understanding of the social determinants of the spread of close-contact infections, and of the importance of long-lasting contacts for effective transmission to occur. Still, little is known about the relationship between two of the most critical identified factors (frequency of contacts and duration of exposure) and how this relationship applies to different types of infections. By integrating data from two independently collected social surveys (Polymod and time use), we propose a model that combines these two transmission determinants into a new epidemiologically relevant measure of contacts: the number of "suitable" contacts, which is the number of contacts that involve a sufficiently long exposure time to allow for transmission. The validity of this new epidemiological measure is tested against Italian serological data for varicella and parvovirus-B19, with uncertainty evaluated using the Bayesian melding technique. The model performs quite well, indicating that the interplay between time of exposure and contacts is critical for varicella transmission, while for B19 it is the duration of exposure that matters for transmission.

Status (in)consistency in education and violent parenting practices towards children.

Violent childrearing practices represent an invisible threat for global health and human development. Leveraging underused information on child discipline methods, this study explores the relationship between parental educational similarity and violent childrearing practices, testing a new potential pathway through which parental educational similarity may relate to child health and wellbeing over the life course. The study uses data from Multiple Indicator Cluster Surveys (MICS) and Demographic and Health Surveys (DHS) covering 27 sub-Saharan African (SSA) countries. Results suggest that couples where partners share the same level of education (homogamy) are less likely to adopt violent childrearing practices relative to couples where partners face status inconsistency in education (heterogamy), with differences by age of the child, yet less so by sex and birth order. Homogamous couples where both partners share high levels of education are also less (more) likely to adopt physically violent (non-violent) practices relative to homogamous couples with low levels of education. Relationships are stronger in countries characterized by higher GDP per capita, Human Development Index, and female education, yet also in countries with higher income and gender inequalities. Besides stressing the importance of female education, these findings underscore the key role of status concordance vs discordance in SSA partnerships. Tested micro-level mechanisms and country-level moderators only weakly explain result heterogeneity, calling for more research on the topic.

Does unemployment worsen babies' health? A tale of siblings, maternal behaviour, and selection.

We study in-utero exposure to economic fluctuations on birth outcomes by exploiting geographical variation in the unemployment rate across local areas in England, and by comparing siblings born to the same mother. Using rich individual data from hospital administrative records for 2003-2012, babies' health is found to be strongly pro-cyclical. This overall result masks marked differences between babies born in the most affluent areas whose health at birth improves in a recession, and babies born in the average-to-lowest income deprived areas whose health deteriorates. Maternal alcohol consumption, smoking, and delay in the first antenatal care assessment - combined with parental income loss, are found to drive the results. While differences in maternal risky behaviours can explain the heterogenous effects.

Optimising assessments of the epidemiological impact in The Netherlands of paediatric immunisation with 13-valent pneumococcal conjugate vaccine using dynamic transmission modelling.

This work is the first attempt to quantify the overall effects of a 13-valent pneumococcal conjugate vaccine (PCV13) vaccination programme in the Dutch population taking into account all the direct and indirect effects of the vaccine on invasive pneumococcal disease. Using available Dutch data, a dynamic transmission model for the spread of pneumococci and potential subsequent invasive pneumococcal disease has been adapted to the Dutch setting. Overall, invasive pneumococcal disease cases in the Netherlands are predicted to decrease from a pre-vaccination level of 2623 cases annually to 2475, 2289, 2185, 2179, and 2178 cases annually 5-, 10-, 20-, 30-, and 40-years, respectively, post-vaccination. Therefore, vaccination with PCV13 in the Netherlands is predicted to lower invasive pneumococcal disease cases per year by up to 445 cases in the medium- to long-term. The results are quite robust for the sensitivity analyses performed on the parameters that regulate herd immunity and competition between vaccine and non-vaccine types.

Cost-effectiveness of pertussis booster vaccination in the Netherlands.

The aim of the current study is to estimate the epidemiological and economical consequences of several extended pertussis booster vaccination strategies and to explore the impact of parameters surrounded by large uncertainty on the cost-effectiveness. We developed an age structured transmission dynamic model to evaluate the impact of programs targeting (i) adolescents or adults using a single booster dose, (ii) a combination of adolescent and adult vaccination, and (iii) an every 10 years booster dose. The base case analysis, that is a single adolescent booster administered at the age of 12 years, resulted in a reduction of pertussis infections. However, due to an increase in the number of symptomatic infections in adults, the benefits in terms of QALYs gained and costs saved in children were partly offset. Despite these negative indirect effects in the adult population, administering an additional booster dose could still be considered cost effective with an ICER of €4200 per QALY gained. Combining an adolescent booster dose at the age of 10 (most cost-effective age for a single adolescent booster dose) with an adult (18-30 years) booster dose always resulted in favorable ICERs (<€10,000/QALY). Finally the every 10 year booster dose resulted in an ICER of €16,900 per QALY. The impact of different assumptions regarding the disease epidemiology, disease-related parameters, and vaccination program-related issues was limited. To conclude, we show that extended pertussis booster vaccination strategies are likely to be considered as cost-effective.

Dynamic models for health economic assessments of pertussis vaccines: what goes around comes around....

Despite childhood vaccination programs, pertussis remains endemic. To reduce the burden of pertussis, various extended pertussis vaccination strategies have been suggested. The aim of this article is to evaluate dynamic models used to assess the cost-effectiveness of vaccination. In total, 16 studies using a dynamic model were included, of which four also studied the cost-effectiveness of extended pertussis vaccination strategies. Generally, adolescent vaccination was found to be cost effective, but not highly effective in protecting infants too young to be vaccinated. The models also predicted that owing to age shifts, reduced pertussis disease in adolescents and young adults comes with an increase in later stages of life. This underpins the use of dynamic transmission models for interventions directed against pertussis. In future, dynamic transmission models for pertussis should be used widely to further enhance understanding of pertussis epidemiology and of extended pertussis vaccination programs that are currently considered in various countries.