the vulnerable. COVID-19 and the drug supply chain: from production and trafficking to use 6 Drug consumption Drug shortages have been reported and could have negative health consequences for people with drug use disorders Many countries have reported drug shortages at the retail level, with reports of heroin shortages in Europe, South-West Asia and North America in particular. Drug supply shortages can go together with an overall decrease in consumption (for example, of drugs that are mostly consumed in recreational setting such as bars and clubs) but may also, especially in the case of heroin, lead to the consumption of harmful domestically-produced substances, as well as more harmful patterns of drug use by people with drug use disorders. In terms of alternatives, some countries in Europe have warned that heroin users may switch to substances such as fentanyl and its derivatives. An increase in the use of pharmaceutical products such as benzodiazepines and buprenorphine has also been reported, to the extent that their price has doubled in some areas. Harmful patterns deriving from drug shortages include an increase in injecting drug use and the sharing of injecting equipment and other drug paraphernalia, all of which carry the risk of spreading blood-borne diseases, such as HIV/AIDS and hepatitis C, and COVID-19 itself. Risks resulting from drug overdose may also increase among people who inject drugs and who are infected with COVID-19. Some countries have reported that the activities of organizations providing support to people who use drugs have been severely affected. In response to a reduction in the accessibility of treatment service provision during the lockdown, some countries have increased low-threshold services and reduced barriers for obtaining opiate-substitution medication; for example, allowing pharmacies to dispense methadone, as in the United Kingdom. Other countries, however, have reported difficulties in maintaining services for drug users. Economic difficulties caused by COVID-19 could change drug consumption for the worse In the long run, the economic downturn caused by the COVID-19 crisis has the potential to lead to a lasting transformation of the drug markets. The economic difficulties caused by the COVID-19 crisis may affect people who are already in a position of socioeconomic disadvantage harder than others. This could lead to an increase in the number of people resorting to illicit activities linked to drugs in order to make a living (production, transport, etc.) and/or being recruited into drug trafficking organizations. Based on the experiences of the economic crisis of 2008, it is fair to assume that the economic downturn may lead to reductions in drug-related budgets among Member States, an overall increase in drug use, with a shift towards cheaper drugs, and a shift in patterns of use towards injecting drugs and to substances with an increased risk of harm due to a greater frequency of injections. COVID-19 and the drug supply chain: from production and trafficking to use 7 POLICY IMPLICATIONS Mitigating the potentially harmful effects of the COVID-19 pandemic on drug markets and on the ability of countries to control drug production, trafficking and use requires adaptive and quick responses by the international community. In the short term, drug market disruptions may lead to an increase in harmful drug use practices and to novel strategies by drug trafficking groups aiming to overcome obstacles. People who use drugs may increasingly access the darknet in order to overcome the effects of street control and drug delivery by mail could become more popular. The economic downturn caused by the COVID-19 crisis could, in the medium-term, lead to further increases in drug production, trafficking and use. The crisis may have a transformative effect on drug markets and may exacerbate the socioeconomic situation of vulnerable groups who in turn may increasingly resort to illicit activities. Indeed, an increasing number of people may resort to illicit activities to compensate for the loss of licit income and unemployment. Once restrictions are lifted, economic shocks may also prompt an increase in drug consumption, as observed in the past. In parallel, the economic crisis will limit the capacity of Member States to curb drug production and mitigate harms resulting from drug consumption, if fewer funds are available for counter-narcotic programmes and alternative development, as well as for drug treatment and prevention programmes. Tackling drug trafficking remains an international responsibility. Most of the demand for trafficked substances comes from countries other than those where drugs are produced and most drug-related income is generated in destination countries. As such, tackling drug trafficking remains a shared responsibility that requires a concerted international effort targeting the new challenges related to the COVID-19 pandemic, which are affecting countries of supply, transit and destination. The evidence collected so far suggests that the COVID-19 pandemic and the measures to contain it, are affecting the drug supply chain, from production and trafficking to consumption, to varying degrees. Close monitoring of the supply chain and of drug use patterns and their consequences is paramount in order to assess whether the observed changes are only