The value of manual backward contact tracing to control COVID-19 in practice, the Netherlands, February to March 2021:a pilot study

BackgroundContact tracing has been a key component of COVID-19 outbreak control. Backward contact tracing (BCT) aims to trace the source that infected the index case and, thereafter, the cases infected by the source. Modelling studies have suggested BCT will substantially reduce SARS-CoV-2 transmission in addition to forward contact tracing.AimTo assess the feasibility and impact of adding BCT in practice.MethodsWe identified COVID-19 cases who were already registered in the electronic database between 19 February and 10 March 2021 for routine contact tracing at the Public Health Service (PHS) of Rotterdam-Rijnmond, the Netherlands (pop. 1.3 million). We investigated if, through a structured questionnaire by dedicated contact tracers, we could trace additional sources and cases infected by these sources. Potential sources identified by the index were approached to trace the source's contacts. We evaluated the number of source contacts that could be additionally quarantined.ResultsOf 7,448 COVID-19 cases interviewed in the study period, 47% (n = 3,497) indicated a source that was already registered as a case in the PHS electronic database. A potential, not yet registered source was traced in 13% (n = 979). Backward contact tracing was possible in 62 of 979 cases, from whom an additional 133 potential sources were traced, and four were eligible for tracing of source contacts. Two additional contacts traced had to stay in quarantine for 1 day. No new COVID-19 cases were confirmed.ConclusionsThe addition of manual BCT to control the COVID-19 pandemic did not provide added value in our study setting.</p

Distillation of knowledge for effective alcohol policy making

Alcohol consumption is one of the most debated risk factors for disease, while at the same time it is almost impossible to imagine a world without it. Alcohol consumption is associated with an increased risk for several diseases, for which each glass of alcohol increases your disease risk. However, the alleged beneficial association between moderate alcohol consumption and cardiovascular disease has not yet been fully clarified. Both conducting alcohol research and implementing alcohol policy come with challenges. The thesis titled "Distillation of knowledge for effective alcohol policy making" presents research in both areas. First, we investigated how alcohol research can be further improved: with the biomarker ethyl glucuronide as a more objective measure of alcohol consumption, and with the relatively new study design called Mendelian randomization. Both provide opportunities for future alcohol research. In the second part we examined the current performance of alcohol policy by assessing adherence to current alcohol consumption guidelines in Europe and South America. When is the scientific knowledge on alcohol sufficient to distill alcohol policy from it? This question we try to answer in the last part of this thesis. Based on the current scientific evidence – the best evidence we have so far - we conclude that there is sufficient ground for better implementation of population-wide strategies globally to reduce alcohol use. Science will continue to play an important role in this respect in continually re-evaluating the effectiveness and necessity of the implemented alcohol policy