Evaluation of Sars-Cov-2 infection in vaccinated persons: Case of the general hospital of Douala (Cameroon)

Coronavirus infection is a public health problem worldwide despite the implementation of several control measures and vaccination. The purpose of this study was to evaluate SARS-Cov-2 infection in vaccinated patients. Methods: A cross-sectional study was conducted at the Douala General Hospital from January to June 2022. Patients of both sexes, aged over 18 years, vaccinated against SARS-CoV-2 were included. Information regarding socio-demographic data, clinical manifestations, and SARS-CoV-2 vaccination was collected by individual interview. Nasopharyngeal secretions were collected by swabbing and transported to the laboratory. SARS-CoV-2 was detected using a rapid diagnostic test (antigen test) and a molecular test targeting the ORF and N genes (Daan gene® kit). Data were analyzed using StatView v5.0 and GraphPad v5.03. Results: A total of 62 patients were selected and women represented 64.5%. The mean age of the patients was 45.58 ± 13.14 with a predominance of the 40 to 50 year old age group. The patients had been vaccinated with four SARS-CoV-2 vaccines (Vaxzeria®, Jcovden-COVID-19 Vaccine Janssen®, Comirnaty Biontech-Pfizer® and Sinovac®); 50.9% of them had received the Janssen®. Viremia was higher in men aged 30 to 60 years and in those who received Janssen® vaccine. The mild form of the infection was the most common clinical presentation with 80.4% of cases. There was a delay of 3 to 5 months between vaccine administration and COVID 19 infection. Conclusion: Most of the vaccinated persons developed mild forms of COVID-19 with a mean delay of 3 to 5 months; the viremia was higher in men, in those who received the Janssen® vaccine and in those aged 30 to 60 years. Vaccination remains an effective means of preventing severe forms of SARSCoV-2 infection.