Prevalence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Antibodies in the Mozambican Population: A Cross-Sectional Serologic Study in 3 Cities, July-August 2020

SARS-CoV-2 in Mozambican primary school-aged children at Maputo City and Province: a cross-sectional study from a low-income country

BACKGROUND

Seroprevalence studies provide information on the true extent of infection and capture demographic and geographic differences, indicating the level of immunity against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). We sought to provide local evidence of SARS-CoV-2 exposure in school-aged children during in-class teaching in Maputo City and Province, Mozambique.

METHODS

Between August and November 2022, we performed a cross-sectional study in school-aged children in four schools in rural, peri-urban, and urban areas of Maputo City and Province. A point-of-care test was used to evaluate SARS-CoV-2 antigens and anti-SARS-CoV-2-specific immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. Descriptive statistics were used to estimate the prevalence of the antigens and antibodies. Multiple logistic regression models were used to estimate the adjusted odds ratio (AOR) for the factors associated with anti-SARS-CoV-2 antibodies.

RESULTS

A total of 736 school-aged children were analyzed. The prevalence of the SARS-CoV-2 antigen was 0.5% (4/736). The prevalence of SARS-CoV-2 antigens was 0.0% (0/245), 0.8% (2/240) and 0.8% (2/251), in the rural, peri-urban and urban areas respectively. The overall seroprevalence of the anti-SARS-CoV-2 antibodies (IgG or IgM) was 80.7% (594/736). In rural area anti-SARS-CoV-2 IgG or IgM antibodies were detected in 76.7% (188/245), while in peri-urban area they were detected in 80.0% (192/240) and in urban area they were detected in 85.3% (214/251). In the adjusted logistic regression model, school-aged children from the urban area were more likely to have anti-SARS-CoV-2 IgG or IgM antibodies than were school-aged children from the rural area (adjusted odds ratio: 1.679; 95% CI: 1.060-2.684; p-value = 0.028).

CONCLUSIONS

During the in-class teaching period, active SARS-CoV-2 cases in school-aged children were observed. More than half of the school-aged children were exposed to SARS-CoV-2, and SARS-CoV-2 was significantly more common in the schools at the urban area than in the school in the rural area at Maputo City and Province.

Trends in SARS-CoV-2 seroprevalence among pregnant women attending first antenatal care visits in Zambia: A repeated cross-sectional survey, 2021-2022

SARS-CoV-2 serosurveys help estimate the extent of transmission and guide the allocation of COVID-19 vaccines. We measured SARS-CoV-2 seroprevalence among women attending ANC clinics to assess exposure trends over time in Zambia. We conducted repeated cross-sectional SARS-CoV-2 seroprevalence surveys among pregnant women aged 15-49 years attending their first ANC visits in four districts of Zambia (two urban and two rural) during September 2021-September 2022. Serologic testing was done using a multiplex bead assay which detects IgG antibodies to the nucleocapsid protein and the spike protein receptor-binding domain (RBD). We calculated monthly SARS-CoV-2 seroprevalence by district. We also categorized seropositive results as infection alone, infection and vaccination, or vaccination alone based on anti-RBD and anti-nucleocapsid test results and self-reported COVID-19 vaccination status (vaccinated was having received ≥1 dose). Among 8,304 participants, 5,296 (63.8%) were cumulatively seropositive for SARS-CoV-2 antibodies from September 2021 through September 2022. SARS-CoV-2 seroprevalence primarily increased from September 2021 to September 2022 in three districts (Lusaka: 61.8-100.0%, Chongwe: 39.6-94.7%, Chipata: 56.5-95.0%), but in Chadiza, seroprevalence increased from 27.8% in September 2021 to 77.2% in April 2022 before gradually dropping to 56.6% in July 2022. Among 5,906 participants with a valid COVID-19 vaccination status, infection alone accounted for antibody responses in 77.7% (4,590) of participants. Most women attending ANC had evidence of prior SARS-CoV-2 infection and most SARS-CoV-2 seropositivity was infection-induced. Capturing COVID-19 vaccination status and using a multiplex bead assay with anti-nucleocapsid and anti-RBD targets facilitated distinguishing infection-induced versus vaccine-induced antibody responses during a period of increasing COVID-19 vaccine coverage in Zambia. Declining seroprevalence in Chadiza may indicate waning antibodies and a need for booster vaccines. ANC clinics have a potential role in ongoing SARS-CoV-2 serosurveillance and can continue to provide insights into SARS-CoV-2 antibody dynamics to inform near real-time public health responses.

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

Surveillance of COVID-19/SARS-CoV-2 dynamics is crucial to understanding natural history and providing insights into the population's exposure risk and specific susceptibilities. This study investigated the seroprevalence of SARS-CoV-2 antibodies, its predictors, and immunological status among unvaccinated patients in Cameroon. A multicentre cross-sectional study was conducted between January and September 2022 in the town of Douala. Patients were consecutively recruited, and data of interest were collected using a questionnaire. Blood samples were collected to determine Immunoglobin titres (IgM and IgG), interferon gamma (IFN- γ) and interleukin-6 (IL-6) by ELISA, and CD4+ cells by flow cytometry. A total of 342 patients aged 41.5 ± 13.9 years were included. Most participants (75.8%) were asymptomatic. The overall crude prevalence of IgM and IgG was 49.1% and 88.9%, respectively. After adjustment, the seroprevalence values were 51% for IgM and 93% for IgM. Ageusia and anosmia have displayed the highest positive predictive values (90.9% and 82.4%) and specificity (98.9% and 98.3%). The predictors of IgM seropositivity were being diabetic (aOR = 0.23, p = 0.01), frequently seeking healthcare (aOR = 1.97, p = 0.03), and diagnosed with ageusia (aOR = 20.63, p = 0.005), whereas those of IgG seropositivity included health facility (aOR = 0.15, p = 0.01), age of 40-50 years (aOR = 8.78, p = 0.01), married (aOR = 0.21, p = 0.02), fever (aOR = 0.08, p = 0.01), and ageusia (aOR = 0.08, p = 0.01). CD4+, IFN-γ, and IL-6 were impaired in seropositive individuals, with a confounding role of socio-demographic factors or comorbidities. Although the WHO declared the end of COVID-19 as a public health emergency, the findings of this study indicate the need for continuous surveillance to adequately control the disease in Cameroon.

Vaccines, Variants, and Vigilance: Strengthening the Coronavirus Disease 2019 (COVID-19) Public Health Response Through Partnerships and Collaborations

The US Centers for Disease Control and Prevention (CDC); state, tribal, local, and territorial health departments; other US government departments and agencies; the private sector; and international partners have engaged in a real-time public health response to the coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Vaccination, variants, and vigilance were themes that arose in the second year of pandemic response in the United States. The findings included in this supplement emerged from these themes and represent some of the many collaborative efforts to improve public health knowledge and action to reduce transmission, infection, and disease severity.