Closure of US-Mexico border during Covid pandemic increased HIV transmission

Efforts by U.S. authorities to prevent the spread of one virus encouraged the spread of the other, according to a study in ‘The Lancet’

HIV transmission Mexico
A woman shows a syringe used to inject fentanyl, in Tijuana (State of Baja California), in May 2023.Gladys Serrano

The border crossing that separates Tijuana in Mexico from San Diego in the United States is one of the busiest routes in the world for drug trafficking and migration. It is a dynamic human corridor shaped by deportations, inequality, prostitution and marginalization that the authorities decided to close in 2020 to contain infections from one side to the other when the Covid-19 pandemic broke out.

But the closure did not stop drug tourism between the two countries. And instead of preventing the spread of disease, the authorities’ strategy led to an increase in HIV transmission, according to a study recently published in the journal The Lancet. The research was a collaborative project between American scientists from the University of California in San Diego and Irvine that analyzed the spread of the virus through interviews with drug users and genetic data of the pathogen.

According to the investigation, closing the border increased the spread of HIV infection, aggravating cross-border transmission. “Injection drug use is one of the main determinants of acquiring it, and mobility across geographic borders can increase the risk of exposure,” said one of the authors of the work, epidemiologist Britt Skaathun.

According to data his team collected, HIV prevalence among that population reached a rate of 16% in Tijuana, compared to 4% in San Diego. This shows how the geographical and social situation on the northern border of Mexico promotes vulnerability to exposure to infection in the population.

To investigate the relationship between border closures, drug use and HIV transmission, scientists tracked more than 600 citizens, 74% of them men, living in Tijuana and San Diego and who, during the closure of the border crossing, went from one side to the other to buy and consume narcotics.

An NGO worker finds a used syringe while cleaning up waste left behind by addicts, in Nogales, Arizona, in December.
An NGO worker finds a used syringe while cleaning up waste left behind by addicts, in Nogales, Arizona, in December.Gladys Serrano

The first phase of the research consisted of an interview in which respondents answered questions about their demographics, drug use, sexual, and border-crossing behaviors. Every six months, the scientific team took blood samples and tested them for HIV and hepatitis C. According to the results, the increase in transmission occurred just when the border was closed. Restricting passage without other measures to stop clandestine activities did not work as a public health strategy. “Efforts to build a higher wall or policies to stop immigration do not mitigate the spread of HIV,” says Tetyana Vasylyeva, assistant professor of health and disease prevention at the University of California Irvine and the lead author of the study.

To prevent viral spread, adds her colleague Skaathun, a better policy than trying to close a porous border is to establish programs to eliminate HIV transmission at the border, such as substance use treatment and harm reduction services. “These interventions play a key role in reducing incidence, which is why it is necessary to ensure their financing. Combined with other services, they constitute a profitable tool to reduce the economic cost as well as the public health burden of HIV,” says Carlos Magis, who teaches public health at the UNAM School of Medicine in Mexico and is a former director of Censida, the National Center for the Prevention and Control of HIV/AIDS.

Since the 1990s, this agency has developed various community and institutional strategies in Mexico to bring harm reduction services to people who inject drugs, “from deliveries of clean syringes to condoms and treatments for associated diseases,” says Magis.

According to this expert, who has more than 30 years of experience in the field, “thanks to harm reduction programs aimed at the population that injects drugs, between 2003 and 2017, more than 200 infections were avoided per year.” However, President Andrés Manuel López Obrador’s decision to cut off public resources to intermediary organizations and foundations “has put an end to this type of initiative.”

“The reduction of support for syringe exchange programs with the goal of stopping corruption affected community organizations, delivering a great blow. They stopped getting support to carry out harm reduction programs in the field,” warns Clara Fleiz, a researcher at the National Institute of Psychiatry who specializes in the consumption of injected drugs on the country’s northern border.

As explained in a study that she coordinated to monitor the rate of infectious diseases among those who inject drugs in northern Mexico, new cases of HIV have increased in recent years. “If in 2019 the rate in Tijuana was 4.5%, now it is up to 12%,” says the researcher, for whom the government cuts have caused a reduction in the supplies to stop the spread of infections, leading to an increase in risky practices such as sharing needles, and increasing the number of infections.

For this reason, maintains the former director of Censida, it is essential to “recover support for the programs.” In 2019, the U.S. Department of Health and Human Services (HHS) launched a plan to reduce the incidence of HIV by up to 90% by 2030. The plan aims to capitalize on scientific advances in diagnosis, treatment, and prevention in infection control. “We believe that Tijuana and the border region should be provided these funds to help unite efforts in the area,” says Skaathun.

“And we cannot forget the urgent need to address the social and environmental conditions that favor and accompany the increase in these infections,” adds Fleiz. In her opinion, to advance this fight, “we need to respond to the determinants that force people to live on the streets, without access to basic needs such as food and a safe job, and improve access to health services that have worsened in the country.”

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