Prevalence and correlates of SARS-CoV-2 seropositivity among people who inject drugs in the San Diego-Tijuana border region

Abstract

Background People who inject drugs may be at elevated SARS-CoV-2 risk due to their living conditions and/or exposures when seeking or using drugs. No study to date has reported upon risk factors for SARS-CoV-2 infection among people who inject drugs. Methods and findings Between October, 2020 and June, 2021, participants aged ≥18 years from San Diego, California, USA and Tijuana, Baja California, Mexico who injected drugs within the last month underwent interviews and testing for SARS-CoV-2 RNA and antibodies. Binomial regressions identified correlates of SARS-CoV-2 seropositivity. Results Of 386 participants, SARS-CoV-2 seroprevalence was 36.3% (95% CI: 31.5%-41.1%); 92.1% had detectable IgM antibodies. Only 37.5% had previously been tested. Seroprevalence did not differ by country of residence. None tested RNA-positive. Most (89.5%) reported engaging in ≥1 protective behavior [e.g., facemasks (73.5%), social distancing (46.5%), or increasing handwashing/sanitizers (22.8%)]. In a multivariate model controlling for sex, older age, and Hispanic/Latinx/Mexican ethnicity were independently associated with SARS-CoV-2 seropositivity, as was engaging in sex work (AdjRR: 1.63; 95% CI: 1.18–2.27) and having been incarcerated in the past six months (AdjRR: 1.49; 95% CI: 0.97–2.27). Comorbidities and substance using behaviors were not associated with SARS-CoV-2 seropositivity. Conclusions In this community-based study of people who inject drugs in the San Diego-Tijuana border region, over one third were SARS-CoV-2 seropositive, exceeding estimates from the general population in either city. We found no evidence that substance use behaviors were associated with an elevated risk of SARS-CoV-2 infection, but observed that circumstances in the risk environment, notably sex work and incarceration, were independently associated with higher SARS-CoV-2 seroprevalence. Our findings suggest that a binational policy response to COVID-19 mitigation is warranted beyond the closure of the U.S.-Mexico border. Furthermore, decriminalizing sex work and drug use could reduce the burden of COVID-19 among people who inject drugs.

The impact of the COVID-19 pandemic among migrants in shelters in Tijuana, Baja California, Mexico

“… 25 A study conducted among people who inject drugs in Tijuana during the same period as this study found that 36.5% tested SARS-CoV-2 positive. 3 Our seroprevalence results are, therefore, consistent with the review by Hayward et al who concluded that migrants have been disproportionately affected during the pandemic, when compared with the native-born or general population and should be targeted in prevention efforts. 7 A report by the Organisation for Economic Co-operation and Development also concluded that immigrants are over-represented among COVID-19 cases in most countries, with the risk estimated to be twice that of native-born residents.…”

“…According to that study, the seroprevalence for the northwest region (including Baja California) was 40.7% 25. A study conducted among people who inject drugs in Tijuana during the same period as this study found that 36.5% tested SARS-CoV-2 positive 3. Our seroprevalence results are, therefore, consistent with the review by Hayward et al who concluded that migrants have been disproportionately affected during the pandemic, when compared with the native-born or general population and should be targeted in prevention efforts 7.…”

“…Another reason might be that, while nasal swabs have good sensitivity, it is not perfect,26 and pooling methods can also miss some cases 20. However, it’s interesting to mention that the aforementioned study of people who inject drugs did not find any RNA positive individuals 3…”

“… 20 However, it’s interesting to mention that the aforementioned study of people who inject drugs did not find any RNA positive individuals. 3 …”

“…The COVID-19 pandemic has disproportionately impacted socially vulnerable populations 2 3. The pandemic, as well as the measures implemented to control it, and their socioeconomic consequences, can impact migrants both directly (increased risk of transmission) and indirectly (other health and social consequences) 4 5.…”