Overdose and COVID-19 in Baja California, Mexico: The Need for New Methodologies for Understanding Local Trends

Throughout North America, the illicit drug supply’s shift to illicitly manufactured fentanyl (IMF) has fueled a multiwave overdose crisis.¹ In response to the public health crisis, several jurisdictions in the United States and Canada adopted a range of harm reduction strategies. These strategies include take-home naloxone programs, community drug checking services, increased access to medications for opioid use disorder, and the prescription of safe supply medications.

In Mexico, the implementation of harm reduction interventions has been extremely limited.² Faced with opposition at various government levels, local harm reduction programs have struggled to emerge or operate at full scale. Meanwhile, certain Mexican border areas are experiencing a rapid emergence of IMF in their local drug supply,³ leading to a spike in overdoses and an increase in other negative health outcomes for people who use drugs.

AN UNKNOWN CRISIS

The Mexican border cities of Tijuana and Mexicali, both neighboring California, have historically been a major route for drug trafficking of heroin, cocaine, and methamphetamines, with local drug consumption patterns influenced by their geographic proximity to the United States.⁴ In the last few years, these cities have also seen higher levels of overdose cases according to limited data from local harm reduction organizations,⁵ despite the lack of overdoses reported in official Mexican government statistics. However, according to official sources, in all of Mexico, in 2019, only 11 deaths were related to opioids, eight to cocaine, 13 to other stimulants (e.g., methamphetamine), and 167 to polysubstance use.⁶ For a country of more than 120 million people where substance use is known, these numbers are surprisingly low, in spite of the increases in the Baja California cities.

Few studies in Mexico have attempted to estimate the magnitude of overdoses in the country, with only a handful focused on this phenomenon during the COVID-19 pandemic. In 2022, a study by Magis Rodríguez et al. combined overdose reporting by community organizations, news reports, emergency services statistics, and numbers from the federal government’s System of Epidemiological Surveillance of Addictions to estimate fatal and nonfatal overdoses in the country between 2019 and 2020. The research team estimated that there were more than 20 000 nonfatal overdoses and proposed two mortality scenarios—low and high—with rates ranging from 0.6% to 5%, depending on the parameters used.⁷

Our previous research at the community level, using case report forms collected between 2019 and 2021 in the context of an overdose reversal program in the city of Mexicali, documented a 30% increase in reported overdoses following the declaration of a public health emergency because of COVID-19.⁵ This situation coincided with an increase of IMF in the local drug supply, as indicated by the drug testing program set up by the local harm reduction organization.⁸ These numbers in overdose and fentanyl detection⁹ have not been seen in other Mexican cities and emphasize the need to focus on local information to understand the heterogeneity of overdoses in different regions, as suggested by Chandra et al. in this issue of AJPH (p. 599), in the United States.

During the early stages of the public health emergency, we conducted research in collaboration with community organizations that provide services to vulnerable populations in the city of Tijuana. This was done alongside other academic partners from the National University in Mexico City and the University of California, San Diego. Our goal was to understand the prevalence and correlates of COVID-19 among female sex workers to develop better strategies for preventing infection. Although seroprevalence among the general population in the city indicated a prevalence of 22%, our small pilot sample revealed a rate nearly twice as high. This finding underscores the greater burden of the disease on this highly stigmatized and vulnerable population, a trend that could also be expected for other groups such as people who use drugs. Many areas in the country lack the community-based organizations and academic resources necessary to conduct local studies assessing the pandemic’s impact on their cities.

A PATH FORWARD

The use of cause-specific death data to understand overdoses in the United States has produced research that allows for an understanding of regional dynamics. For example, a county-level study by Palau et al.¹⁰ shows how the overdose epidemic has progressed on the northern side of the US‒Mexico border, linking it to specific socioeconomic variables that can help recognize the structural determinants of the problem. However, the modeling of the excess fatal overdoses using CDC WONDER data by substance and geography provides a methodological path for understanding the granular differences that we might have missed from other analyses.

To understand the excess mortality attributable to COVID-19 in Mexico, a group of researchers used cause-specific death data, estimating almost 600 000 lives lost in excess.¹¹ Although the team in Mexico did not include substance use as a specific cause group, the current research by Chandra et al. could serve as an example to be applied to the Mexican context. This additional research of excess of mortality attributable to overdose using death certificates could help emphasize the need to develop a decentralized overdose prevention strategy that recognizes the geographical differences when dealing with the negative consequences of substance use.¹²

As we attempt to understand the impact of COVID-19 on our communities, particularly its influence on the risk of overdoses in North America, it is essential to recognize the value of using similar methodological tools that can provide insights on a local scale. For instance, it is important to ensure that forensic medical services are trained and equipped with the necessary tools to thoroughly investigate all suspected overdose cases, using consistent methods across borders. Community-based organizations play a crucial role in preventing fatal overdoses; thus, standardizing forms for naloxone use can help in understanding variations not only at the county level but also within cities in terms of geographic and substance type trends. Finally, enhancing collaboration among research institutions, public health offices, and harm reduction service organizations from Mexico, Canada, and the United States is crucial for developing unified responses and facilitating the sharing of best practices.