SARS-CoV-2 Neutralizing Antibodies in Three African Countries Following Multiple Distinct Immune Challenges.

BACKGROUND: The COVID-19 pandemic has affected Madagascar, Cameroon, and the Central African Republic (CAR), with each experiencing multiple waves by mid-2022. This study aimed to evaluate immunity against SARS-CoV-2 strains Wuhan (W) and BA.2 (BA.2) among healthcare workers (HCWs) in these countries, focusing on vaccination and natural infection effects. METHODS: HCWs' serum samples were analyzed for neutralizing antibodies (nAbs) against W and BA.2 variants, with statistical analyses comparing responses between countries and vaccination statuses. RESULTS: Madagascar showed significantly higher nAb titers against both strains compared to CAR and Cameroon. Vaccination notably increased nAb levels against W by 2.6-fold in CAR and 1.8-fold in Madagascar, and against BA.2 by 1.6-fold in Madagascar and 1.5-fold in CAR. However, in Cameroon, there was no significant difference in nAb levels between vaccinated and unvaccinated groups. CONCLUSION: This study highlights the complex relationship between natural and vaccine-induced immunity, emphasizing the importance of assessing immunity in regions with varied epidemic experiences and low vaccination rates.

Plasmodium vivax Infections Detected in a Large Number of Febrile Duffy-Negative Africans in Dschang, Cameroon.

The Duffy blood group is a critical receptor for Plasmodium vivax (P. vivax) invasion of red blood cells, and consequently, P. vivax infections were considered rare in sub-Saharan Africa where the prevalence of Duffy-negativity is high. However, recently, P. vivax infections have been found in Duffy-negative Africans throughout the malaria transmission area of sub-Saharan Africa, raising important questions concerning the molecular composition of these P. vivax clones and the red blood cell receptors that facilitate their invasion. Here, we describe an unusually high number of P. vivax infections in febrile Duffy-negative Africans in Dschang, Cameroon (177 of 500 outpatients), as compared with Santchou (two of 400 outpatients) and Kyé-ossi (two of 101 outpatients), in other areas in Cameroon. In the discussion, we speculate on the possible reasons why Dschang might account for the unusually large numbers of P. vivax infections in Duffy-negative individuals living there.

The problem of lost to follow-up of mother-child pairs enrolled in the PMTCT program in Dschang District Hospital-Cameroon.

High rates of lost to follow-up (LTFU) in the Prevention of Mother-To-Child Transmission of HIV (PMTCT) programs in Cameroon will only contribute in hindering the successful implementation of the program. The objective of this study was to determine the reasons of LTFU of mother-child pairs enrolled in the PMTCT program in Dschang District Hospital (DDH): Cameroon. Methods: A retrospective cohort study was carried out in HIV+ exposed children delivered in the DDH from1st Jan 2012 - 31st Dec 2014, who were greater than or equal to 18 months at the study period (1st August - 30th September 2016) and whose mothers were enrolled in the PMTCT program for at least 3 months. Children were considered LTFU if they did not return to the hospital for the establishment of their HIV status at 18 months. A complementary cross-sectional study was done whereby a structured questionnaire was administered to the LTFU group via telephone calls, in order to determine the causes of LTFU. Data was collected from hospital registers and analyses done using Epi info 7.1.3.3 software. Results: A total of 141 mother-child pairs were eligible for the study, 76 were reachable via phone calls and 36 (47.37%) met the case definition of LTFU. Out of the 36 (47.37%) children LTFU, lack of information, 19(65.52%); lack of support from male partners, 4(11.11%); Poor behavior of health personnel, 2 (5.56%); forgetfulness, negligence/time wasting, unavailability of results, fear of child being infected, and family problems were all listed at equal proportions of, 3(6.90%) as well as financial problem, 1 (2.78%) were all causes of LTFU identified in this study.

Vaccine coverage and determinants of incomplete vaccination in children aged 12-23 months in Dschang, West Region, Cameroon: a cross-sectional survey during a polio outbreak.

BACKGROUND: Inadequate immunization coverage with increased risk of vaccine preventable diseases outbreaks remains a problem in Africa. Moreover, different factors contribute to incomplete vaccination status. This study was performed in Dschang (West Region, Cameroon), during the polio outbreak occurred in October 2013, in order to estimate the immunization coverage among children aged 12-23 months, to identify determinants for incomplete vaccination status and to assess the risk of poliovirus spread in the study population. METHODS: A cross-sectional household survey was conducted in November-December 2013, using the WHO two-stage sampling design. An interviewer-administered questionnaire was used to obtain information from consenting parents of children aged 12-23 months. Vaccination coverage was assessed by vaccination card and parents' recall. Chi-square test and multilevel logistic regression model were used to identify the determinants of incomplete immunization status. Statistical significance was set at p < 0.05. RESULTS: Overall, 3248 households were visited and 502 children were enrolled. Complete immunization coverage was 85.9% and 84.5%, according to card plus parents' recall and card only, respectively. All children had received at least one routine vaccination, the OPV-3 (Oral Polio Vaccine) coverage was >90%, and 73.4% children completed the recommended vaccinations before 1-year of age. In the final multilevel logistic regression model, factors significantly associated with incomplete immunization status were: retention of immunization card (AOR: 7.89; 95% CI: 1.08-57.37), lower mothers' utilization of antenatal care (ANC) services (AOR:1.25; 95% CI: 1.07-63.75), being the ≥ 3(rd) born child in the family (AOR: 425.4; 95% CI: 9.6-18,808), younger mothers' age (AOR: 49.55; 95% CI: 1.59-1544), parents' negative attitude towards immunization (AOR: 20.2; 95% CI: 1.46-278.9), and poorer parents' exposure to information on vaccination (AOR: 28.07; 95 % CI: 2.26-348.1). Longer distance from the vaccination centers was marginally significant (p = 0.05). CONCLUSION: Vaccination coverage was high; however, 1 out of 7 children was partially vaccinated, and 1 out of 4 did not complete timely the recommended vaccinations. In order to improve the immunization coverage, it is necessary to strengthen ANC services, and to improve parents' information and attitude towards immunization, targeting younger parents and families living far away from vaccination centers, using appropriate communication strategies. Finally, the estimated OPV-3 coverage is reassuring in relation to the ongoing polio outbreak.