Large Diffusion of Severe Acute Respiratory Syndrome Coronavirus 2 After the Successive Epidemiological Waves, Including Omicron, in Guinea and Cameroon: Implications for Vaccine Strategies

Abstract

Background We aimed to estimate the SARS-CoV-2 seroprevalence among the general population in Conakry, Guinea and Yaounde, Cameroon after the COVID-19 Omicron wave. Methods We conducted population-based age-stratified seroprevalence surveys in Conakry, Guinea and Yaounde, Cameroon (May and June 2022). We collected demographic, epidemiologic information and dried blood spot (DBS) samples that were tested for SARS-CoV-2 IgG antibodies using recombinant nucleocapsid (NC) and spike (SP) proteins with a 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 SP and NC was 71.57% (95% 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 to be seropositive than male. 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 degree were independently associated with seropositivity. Conclusion These findings show a high community transmission after the different epidemiological waves including Omicron especially among people above 40 years old. 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.

Serological surveillance reveals a high exposure to SARS-CoV-2 and altered immune response among COVID-19 unvaccinated Cameroonian individuals

“…Patients aged 60–70 years were less at risk of IgM seropositivity, which is consistent with earlier studies [ 17 , 25 , 30 , 39 , 43 , 44 ]. In Bosnia and Herzegovina, Prguda-Mujic and colleagues reported a reduced risk of positive anti-SARS CoV-2 Ig levels in patients aged over 50 years old [ 30 ].…”

“…among blood donors from Douala and Yaoundé (66.3% to 98.4%) [ 38 ], and Diallo et al . among unvaccinated individuals (74.8%) after the Omicron wave [ 39 ]. Lower values were reported among dental teams in Germany (5.2%) [ 40 ] and young adults in Sweden (22.4%) [ 20 ].…”

“…The crude and adjusted prevalence of IgG was 88.9% and 93% in this study. Such a high prevalence estimate was also reported in Cameroon by Ndongo Ateba et al in Yaounde (18.6% to 51.3%) [35], Mansuy et al in pregnant women from Yaounde ´(77%) [36], Njuwa Fai et al in a community-based study from Yaounde ´(24%) [34], Deutou Wondeu et al among PLOS GLOBAL PUBLIC HEALTH university staff and students (71.3%) in Bandjoun, a kingdom in the West Region of Cameroon [37], Sandie et al among blood donors from Douala and Yaounde ´(66.3% to 98.4%) [38], and Diallo et al among unvaccinated individuals (74.8%) after the Omicron wave [39]. Lower values were reported among dental teams in Germany (5.2%) [40] and young adults in Sweden (22.4%) [20].…”

Serological surveillance reveals a high exposure to SARS-CoV-2 and altered immune response among COVID-19 unvaccinated Cameroonian individuals

“…Patients aged 60 -70 years were less at risk of IgM seropositivity, which is consistent with earlier studies [14,19,22,36,38,39]. In Bosnia and Herzegovina, Prguda-Mujic and colleagues reported a reduced risk of positive anti-SARS CoV-2 Ig levels in patients aged over 50 years old [19].…”

“…Before our study, IgM seroprevalence estimates were available from studies conducted among health care workers and the general population in the town of Yaoundé [29][30][31]. [35], and Diallo et al among unvaccinated individuals (74.8%) after the Omicron wave [36]. Lower values were reported among dental teams in Germany (5.2%) [37] and young adults in Sweden (22.4%) [25].…”