Large Diffusion of Severe Acute Respiratory Syndrome Coronavirus 2 After the Successive Epidemiological Waves, Including Omicron, in Guinea and Cameroon: Implications for Vaccine Strategies
Mamadou Saliou Kalifa Diallo, Marie Amougou‐Atsama, Ahidjo Ayouba, Cécé Kpamou, Eric Mimbe, Guillaume Thaurignac, Haby Diallo, Nadine Boutgam Lamare, Julie Bouillin, Abdoul Karim Soumah, Sébastien Awono Noah, Emilande Guichet, Alpha Kabinet Kéita, Marie Varloteaux, Martine Peeters, Anne‐Cécile Zoung‐Kanyi Bissek, Abdoulaye Touré, Éric Delaporte, Charles Kouanfack
Abstract
Background: We aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence among the general population in Conakry, Guinea and Yaounde, Cameroon after the coronavirus disease 2019 Omicron wave. Methods: We conducted population-based, age-stratified seroprevalence surveys in Conakry and Yaounde (May and June 2022). We collected demographic and epidemiologic information and dried blood spot samples that were tested for SARS-CoV-2 immunoglobulin G (IgG) antibodies using recombinant nucleocapsid and spike proteins with Luminex technology. Results: Samples were obtained from 1386 and 1425 participants in Guinea and Cameroon, respectively. The overall age-standardized SARS-CoV-2 IgG seroprevalence against spike and nucleocapsid proteins was 71.57% (95% confidence interval [CI], 67.48%-75.33%) in Guinea and 74.71% (95% CI, 71.99%-77.25%) in Cameroon. Seroprevalence increased significantly with age categories. Female participants were more likely than male participants to be seropositive. The seroprevalence in unvaccinated participants was 69.6% (95% CI, 65.5%-73.41%) in Guinea and 74.8% (95% CI, 72.04%-77.38%) in Cameroon. In multivariate analysis, only age, sex, and education were independently associated with seropositivity. Conclusions: These findings show a high community transmission after the different epidemiological waves including Omicron, especially among people aged >40 years. In addition, our results suggest that the spread of SARS-CoV-2 has been underestimated as a significant proportion of the population has already contracted the virus and that vaccine strategies should focus on vulnerable populations.