Prevalence of SARS-CoV-2 infection in Baja California, Mexico: Findings from a community-based survey in February 2021 in the Mexico-United States border

Abstract

Between March 2020 and February 2021, the state of Baja California, Mexico, which borders the United States, registered 46,118 confirmed cases of COVID-19 with a mortality rate of 238.2 deaths per 100,000 residents. Given limited access to testing, the population prevalence of SARS-CoV-2 infection is unknown. The objective of this study is to estimate the seroprevalence and real time polymerase chain reaction (RT-PCR) prevalence of SARS-CoV-2 infection in the three most populous cities of Baja California prior to scale-up of a national COVID-19 vaccination campaign. Probabilistic three-stage clustered sampling was used to conduct a population-based household survey of residents five years and older in the three cities. RT-PCR testing was performed on nasopharyngeal swabs and SARS-CoV-2 seropositivity was determined by IgG antibody testing using fingerstick blood samples. An interviewer-administered questionnaire assessed participants’ knowledge, attitudes, and preventive practices regarding COVID-19. In total, 1,126 individuals (unweighted sample) were surveyed across the three cities. Overall prevalence of SARS-CoV-2 infection by RT-PCR was 7.8% (95% CI 5.5–11.0) and IgG seroprevalence was 21.1% (95% CI 17.4–25.2). There was no association between border crossing in the past 6 months and SARS-CoV-2 prevalence (unadjusted OR 0.40, 95%CI 0.12–1.30). While face mask use and frequent hand washing were common among participants, quarantine or social isolation at home to prevent infection was not. Regarding vaccination willingness, 30.4% (95% CI 24.4–3 7.1) of participants said they were very unlikely to get vaccinated. Given the high prevalence of active SARS-CoV-2 infection in Baja California at the end of the first year of the pandemic, combined with its low seroprevalence and the considerable proportion of vaccine hesitancy, this important area along the Mexico-United States border faces major challenges in terms of health literacy and vaccine uptake, which need to be further explored, along with its implications for border restrictions in future epidemics.

A community based seroprevalence of SARS‐CoV‐2 antibodies in Somali Region, Eastern Ethiopia

“…One of the likely causes of the COVID‐19 virus' quick proliferation in Ethiopia was reported to be the constant flow of immigrants and the inadequate border protection 33 . Likewise similar high prevalence rates in border towns and cities were reported in Ruili City of China‐Myanmar border 34 and in Baja California of Mexico‐USA border 35 …”

“…33 Likewise similar high prevalence rates in border towns and cities were reported in Ruili City of China-Myanmar border 34 and in Baja California of Mexico-USA border. 35 High seroprevalence rate reported in Jigjiga district might be due to its large population size and relatively urbanization, where there is considerable overcrowding. Higher seroprevalence levels were observed in cities with large populations in Colombia.…”

“… 33 Likewise similar high prevalence rates in border towns and cities were reported in Ruili City of China‐Myanmar border 34 and in Baja California of Mexico‐USA border. 35 …”

Preventive measures against the COVID-19 pandemic in Mexico: A cross-sectional study

“…According to Zazueta et al ( 10 ), during the COVID-19 pandemic, face mask usage was reported to be up to 89%. According to Bults et al ( 4 ), the face mask usage during the H1N1 pandemic was of 71%.…”