Post-migration infection with SARS-CoV-2 in Venezuelan migrants: A laboratory-based epidemiological observational study

Background

Since 2015, over 6 million Venezuelans migrated to Colombia and neighboring countries. While most people adhered to lockdown measures, migrants kept moving during the COVID-19 pandemic.

Method

To investigate the extent of migration-associated SARS-CoV-2 infections, we interviewed 1209 adult Venezuelan migrants upon arrival to Bucaramanga, Colombia, 200 km from the Colombian-Venezuelan border along the main migration route during April–September 2021, collected individual-level socio-economic and clinical data, sampled blood and saliva, and assessed SARS-CoV-2 infection by serological, molecular and phylogenetic tools.

Results

SARS-CoV-2 RT-PCR positivity was 1.9 % (95 % Confidence Interval (CI), 1.2–2.9) without varying significantly over the study period (chi-square, p = 0.922) and significantly associated with stay in Colombia >14 days (p = 0.018; prevalence ratio 3.3, 95 % CI, 1.2–8.7). Pre-existing SARS-CoV-2-specific antibodies were neither significantly associated with preventing infection (Chi-square, p = 0.188), nor symptom development (Fisher, p = 0.246). Predominance and time of detection of SARS-CoV-2 Mu and Gamma variants in migrants in comparison to available genomic data suggested infection predominantly in Colombia. SARS-CoV-2 IgG-based seroprevalence was 34.2 % (95 % CI, 31.5–36.9). Detection of SARS-CoV-2-specific antibodies was significantly associated with previous contact with infected individuals (p = 0.002).

Conclusions

SARS-CoV-2 infection occurred predominantly after immigration, potentially facilitated by densely populated border camps. Improved infrastructure and health care will prevent migration-associated spread of COVID-19 and other infectious diseases.