Social Norms and Free-Riding in Influenza Vaccine Decisions: An Online Experiment

‘Nudges’ based on social norm messages can be used in public health interventions to change behaviour. In the context of influenza vaccination, messages about high coverage levels may signal a bandwagoning effect that encourages vaccination, but also a low individual risk of infection, promoting a free riding effect that discourages vaccination. The interplay between these two factors can affect decision-making differently at varying population coverage levels, making the impact of nudges on intentions to vaccinate ambiguous to predict. We aim to causally measure the effects of different social norms via messages about population vaccination coverage rates on influenza vaccination intention. In an online experiment, we randomly assign a sample of n=1,365 UK residents aged 18+ years to a control group (with no manipulated information on coverage rate), or to one of seven treatment groups with different messages about the proportion (10%, 25%, 50%, 65%, 75%, 85%, or 95%) of people in their environment who received the flu vaccine. Vaccination intention is measured with self-reported intention and three elicited behavioural measures: (a) opening an online map locating nearby private flu vaccination providers; (b) time looking at this map; and (c) downloading a calendar reminder to vaccinate. Through linear, logistic, and double hurdle regression analysis, we find that individuals treated with greater coverage rates have higher stated vaccination intention than those treated with lower coverage rates. For map-related elicited vaccination intention, however, those with manipulated coverage rates up to 75%, exhibited greater intention at higher treatment intensities, demonstrating possible bandwagoning effects. In groups above this 75% threshold, however, the impact of the treatments when compared to the control – albeit still positive – is lower at greater treatment intensities, signalling the introduction of free riding behaviour and its interplay with bandwagoning above that threshold. Furthermore, individual perceptions on risk of infection and population coverage rates may have an amplifying moderator effect on the relationship between social norms treatments and vaccination intention. Our results imply that health policymakers ought to carefully design interventions based on social norm messages to nudge influenza vaccination in order to promote vaccination, rather than discourage it.

Alive and Kicking? Short-Term Health Effects of a Physician Strike in Germany (Nina Schwarz)

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The Effects of the Great Recession on Health in Germany (Sergej Bechtoldt)

Our study evaluates the effects of the 2008/09 Great Recession on health and health care utilization in the German population. Unlike most other European economies, Germany is generally thought of as being only mildly affected by the Great Recession. Thus, the health impacts of this global economic event are frequently studied, but only a few of these studies focus on Germany. Nevertheless, there was considerable heterogeneity in the impact of the shock at the regional level, thus making Germany a suitable case for studying the Great Recession’s effects.

Using a large individual-level health insurance claims dataset as well as the German Socio-Economic Panel (SOEP) for the period 2005-2011, we contribute to the literature by separately identifying effects of the real economy (like unemployment) and financial sector shocks on several physical and mental health indicators and taking possible heterogeneity between different subpopulations into account.

We apply difference-in-differences as well as synthetic control strategies exploiting regional differences in the real economic effects of the crisis and heterogeneity in the probability of being affected by stock market downturns. Our preliminary results suggest that civil servants’ health mainly reacts to financial shocks whereas employees rather tend to be affected by the real economy.