SARS-CoV-2 Infection and Vaccine Effectiveness among Travelers Screened at the University Hospital of Fann, Dakar, Senegal

Abstract

The COVID-19 pandemic led countries to implement strict public health measures, including systematic screening of international travelers and vaccination, to curb the spread of SARS-CoV-2. Several vaccines have been developed since the onset of the pandemic: inactivated whole-virus vaccines (Sinopharm), recombinant adenovirus vector vaccines encoding the spike protein (AstraZeneca, Johnson & Johnson, Sputnik-V), and mRNA vaccines (Pfizer and Moderna). This study aimed to determine the prevalence of SARS-CoV-2 infection among travelers tested at the University Hospital Center of FANN (CHNU de FANN) and to assess their vaccination status. It was a retrospective study conducted over an 11-month period, from October 2020 to August 2021. All travelers tested at CHNU de FANN were included. Nasopharyngeal samples were analyzed by RT-PCR using the Hummingbird device and Sansure Biotech reagents. Data were extracted from laboratory registers and patient forms, then analyzed with Epi Info software version 3.5.4. Out of 1,164 tests performed, 79 were positive (6.8%). Among the positive cases, 8 patients were under 14 years of age and 8 were over 60. A male predominance was observed (sex ratio = 1.6). Regarding vaccination, 236 travelers were fully vaccinated: Sinopharm (42), Pfizer (44), Johnson & Johnson (35), Moderna (22), AstraZeneca (46), and Sputnik-V (3). However, it should be noted that only patients vaccinated with Sinopharm, Pfizer, Moderna, and Johnson & Johnson developed breakthrough infections. Among the positive cases, 8 had received the Sinopharm vaccine, 4 the Pfizer, 3 the Moderna, and 1 the Johnson & Johnson. These findings highlight the importance of pre-travel screening to limit viral transmission. Further analysis of SARS-CoV-2 variants would be beneficial for enhanced surveillance of viral circulation.