The COVID-19 pandemic and the measures to prevent its spread have had a negative impact on substance use behaviour. It is likely that social distancing and lockdown measures have also altered gambling behaviour, for instance shifting from land-based to online gambling. We used large-scale web scraping to analyse posting behaviour on a major German online gambling forum, gathering a database of more than 200k posts. We examined the usage of different subforums, i.e. terrestrial, online gambling and problem gambling sections, and changes in posting behaviour related to the casino closures that were part of the nationwide restrictions in Germany in 2020. There was a marked increase in newly registered users during the first lockdown compared to the preceding weeks, an increase in the number of posts in the online gambling subforum and concurrent decrease in the terrestrial gambling subforum. Further, the number of short-latency replies was higher during the first lockdown compared to the preceding weeks. Many users who posted in both the online and terrestrial forum contributed at least once to the problem gambling subforum, implying that the topic of problem gambling is widely discussed. Our findings may indicate a shift from terrestrial to online gambling during lockdown, and mirror the general increase in screen time and usage of online platforms after the onset of the COVID-19 pandemic. The analyses help to identify lockdown-related effects on gambling behaviour. These potentially detrimental effects pose a special threat for individuals at risk and may require monitoring and special public health measures.

The COVID-19 pandemic and the measures to prevent its spread have had a negative impact on substance use behaviour and posed a special threat for individuals at risk. Problem gambling is a major public health concern, and it is likely that the lockdown and social distancing measures have altered gambling behaviour, for instance shifting from land-based to online gambling. In this study, we used large-scale web scraping to analyse posting behaviour on a major German online gambling forum, gathering a database of more than 200k posts. We examined the relative usage of different subforums, i.e. terrestrial, online gambling and problem gambling sections, posting frequency, and changes in posting behaviour related to the casino closures that were part of the nationwide restrictions in Germany in 2020. There was a marked increase in the number of newly registered users during the first lockdown compared to the weeks prior to the lockdown, which may reflect a shift from terrestrial to online gambling. Further, there was an increase in the number of posts in the online gambling subforum with a concurrent decrease in the number of posts in the terrestrial gambling subforum. An analysis of user types revealed that a substantial number of users who posted in both the online and terrestrial forum contributed at least once to the problem gambling subforum. This subforum contained the longest posts, which were on average twice as long as the average post. Modelling the relationship between reply frequency and latency between initial posts and replies showed that the number of short-latency replies (i.e. replies posted within seven hours after the initial post) was substantially higher during the first lockdown compared to the preceeding weeks.The increase during the first lockdown may reflect the general marked increase in screen time and/or usage of online platforms and media after the onset of the global COVID-19 pandemic. The analyses may help to identify lockdown-related effects on gambling behaviour. These potentially detrimental effects on mental health, including addiction and problem gambling, may require monitoring and special public health measures.