Assessing the potential of wastewater-based epidemiology to evaluate the impact of COVID-19 policy changes on stimulant use across 17 countries.

BACKGROUND AND AIMS: A limited number of studies have employed wastewater-based epidemiology (WBE) to assess the impact of specific COVID-19 public health directives on stimulant consumption. This study investigates the potential of WBE as a complementary information source to support decision-making, by examining drug use changes during the pandemic.

METHODS

WBE data on stimulant use from 2019 through 2022 was obtained from 17 countries covering a total of 47 wastewater treatment plants worldwide. The Oxford Coronavirus Government Response Tracker stringency index was used to standardize the severity of the COVID-19 interventions across different countries. A multiple linear regression model was fitted for the population-normalized mass loads of amphetamine, cocaine (through its metabolite benzoylecgonine), MDMA, and methamphetamine to investigate whether changes in COVID-19 restrictions influenced stimulant use, controlling for possible week-weekend and spatial effects.

RESULTS

In most locations, WBE suggests that stimulant use was not significantly affected by the COVID-19 interventions, or even increased under the stricter measures. Methamphetamine use showed the largest decrease with increasing policy stringency, with a negative linear relationship found in 19% of cities, followed by MDMA (18%), cocaine (15%) and amphetamine (6%). Social gathering restrictions mainly impacted cocaine and MDMA use, while methamphetamine consumption declined most under stringent travel restrictions.

CONCLUSIONS

This study highlights the heterogeneous effects of the COVID-19 policy changes on stimulant use, even within countries. The ability of WBE to compile consecutive daily estimates proves to be particularly useful to assess the direct effect of specific policy changes on the consumption of different stimulants.