Community-based COVID-19 active case finding and rapid response in the Democratic Republic of the Congo: Improving case detection and response

A community-based coronavirus disease (COVID-19) active case-finding strategy using an antigen-detecting rapid diagnostic test (Ag-RDT) was implemented in the Democratic Republic of Congo (DRC) to enhance COVID-19 case detection. With this pilot community-based active case finding and response program that was designed as a clinical, prospective testing performance, and implementation study, we aimed to identify insights to improve community diagnosis and rapid response to COVID-19. This pilot study was modeled on the DRC's National COVID-19 Response Plan and the COVID-19 Ag-RDT screening algorithm defined by the World Health Organization (WHO), with case findings implemented in 259 health areas, 39 health zones, and 9 provinces. In each health area, a 7-member interdisciplinary field team tested the close contacts (ring strategy) and applied preventive and control measures to each confirmed case. The COVID-19 testing capacity increased from 0.3 tests per 10,000 inhabitants per week in the first wave to 0.4, 1.6, and 2.2 in the second, third, and fourth waves, respectively. From January to November 2021, this capacity increase contributed to an average of 10.5% of COVID-19 tests in the DRC, with 7,110 positive Ag-RDT results for 40,226 suspected cases and close contacts who were tested (53.6% female, median age: 37 years [interquartile range: 26.0-50.0)]. Overall, 79.7% (n = 32,071) of the participants were symptomatic and 7.6% (n = 3,073) had comorbidities. The Ag-RDT sensitivity and specificity were 55.5% and 99.0%, respectively, based on reverse transcription polymerase chain reaction analysis, and there was substantial agreement between the tests (k = 0.63). Despite its limited sensitivity, the Ag-RDT has improved COVID-19 testing capacity, enabling earlier detection, isolation, and treatment of COVID-19 cases. Our findings support the community testing of suspected cases and asymptomatic close contacts of confirmed cases to reduce disease spread and virus transmission.

Serologic response to SARS-CoV-2 in an African population

Official case counts suggest Africa has not seen the expected burden of COVID-19 as predicted by international health agencies, and the proportion of asymptomatic patients, disease severity, and mortality burden differ significantly in Africa from what has been observed elsewhere. Testing for SARS-CoV-2 was extremely limited early in the pandemic and likely led to under-reporting of cases leaving important gaps in our understanding of transmission and disease characteristics in the African context. SARS-CoV-2 antibody prevalence and serologic response data could help quantify the burden of COVID-19 disease in Africa to address this knowledge gap and guide future outbreak response, adapted to the local context. However, such data are widely lacking in Africa. We conducted a cross-sectional seroprevalence survey among 1,192 individuals seeking COVID-19 screening and testing in central Cameroon using the Innovita antibody-based rapid diagnostic. Overall immunoglobulin prevalence was 32%, IgM prevalence was 20%, and IgG prevalence was 24%. IgM positivity gradually increased, peaking around symptom day 20. IgG positivity was similar, gradually increasing over the first 10 days of symptoms, then increasing rapidly to 30 days and beyond. These findings highlight the importance of diagnostic testing and asymptomatic SARS-CoV-2 transmission in Cameroon, which likely resulted in artificially low case counts. Rapid antibody tests are a useful diagnostic modality for seroprevalence surveys and infection diagnosis starting 5-7 days after symptom onset. These results represent the first step towards better understanding the SARS-CoV-2 immunological response in African populations.

Performance and operational feasibility of antigen and antibody rapid diagnostic tests for COVID-19 in symptomatic and asymptomatic patients in Cameroon: a clinical, prospective, diagnostic accuracy study

Background

Real-time PCR is recommended to detect SARS-CoV-2 infection. However, PCR availability is restricted in most countries. Rapid diagnostic tests are considered acceptable alternatives, but data are lacking on their performance. We assessed the performance of four antibody-based rapid diagnostic tests and one antigen-based rapid diagnostic test for detecting SARS-CoV-2 infection in the community in Cameroon.

Methods

In this clinical, prospective, diagnostic accuracy study, we enrolled individuals aged at least 21 years who were either symptomatic and suspected of having COVID-19 or asymptomatic and presented for screening. We tested peripheral blood for SARS-CoV-2 antibodies using the Innovita (Biological Technology; Beijing, China), Wondfo (Guangzhou Wondfo Biotech; Guangzhou, China), SD Biosensor (SD Biosensor; Gyeonggi-do, South Korea), and Runkun tests (Runkun Pharmaceutical; Hunan, China), and nasopharyngeal swabs for SARS-CoV-2 antigen using the SD Biosensor test. Antigen rapid diagnostic tests were compared with Abbott PCR testing (Abbott; Abbott Park, IL, USA), and antibody rapid diagnostic tests were compared with Biomerieux immunoassays (Biomerieux; Marcy l'Etoile, France). We retrospectively tested two diagnostic algorithms that incorporated rapid diagnostic tests for symptomatic and asymptomatic patients using simulation modelling.

Findings

1195 participants were enrolled in the study. 347 (29%) tested SARS-CoV-2 PCR-positive, 223 (19%) rapid diagnostic test antigen-positive, and 478 (40%) rapid diagnostic test antibody-positive. Antigen-based rapid diagnostic test sensitivity was 80·0% (95% CI 71·0–88·0) in the first 7 days after symptom onset, but antibody-based rapid diagnostic tests had only 26·8% sensitivity (18·3–36·8). Antibody rapid diagnostic test sensitivity increased to 76·4% (70·1–82·0) 14 days after symptom onset. Among asymptomatic participants, the sensitivity of antigen-based and antibody-based rapid diagnostic tests were 37·0% (27·0–48·0) and 50·7% (42·2–59·1), respectively. Cohen's κ showed substantial agreement between Wondfo antibody rapid diagnostic test and gold-standard ELISA (κ=0·76; sensitivity 0·98) and between Biosensor and ELISA (κ=0·60; sensitivity 0·94). Innovita (κ=0·47; sensitivity 0·93) and Runkun (κ=0·43; sensitivity 0·76) showed moderate agreement. An antigen-based retrospective algorithm applied to symptomatic patients showed 94·0% sensitivity and 91·0% specificity in the first 7 days after symptom onset. For asymptomatic participants, the algorithm showed a sensitivity of 34% (95% CI 23·0–44·0) and a specificity of 92·0% (88·0–96·0).

Interpretation

Rapid diagnostic tests had good overall sensitivity for diagnosing SARS-CoV-2 infection. Rapid diagnostic tests could be incorporated into efficient testing algorithms as an alternative to PCR to decrease diagnostic delays and onward viral transmission.

Funding

Médecins Sans Frontières WACA and Médecins Sans Frontières OCG.

Translations

For the French and Spanish translations of the abstract see Supplementary Materials section.

Mortality analysis of burns in a developing country: a CAMEROONIAN experience

BACKGROUND

Burns are a serious public health problem worldwide accounting for an estimated 265,000 deaths annually from fires alone. The vast majority (96%) of deaths from fire-related burns occur in low- and middle-income countries and burns are one of the leading causes of disability-adjusted life-years (DALYs) in the developing world. Most burn centres are situated in large cities and are inadequate for the high incidence of injuries. An 8 year review of 440 patients in the Douala General Hospital, showed that the majority of patients burned were males (n = 281, 68.9%), the mean age was 25.2 ± 17.77 years with an admission rate of 69.5% (306 patients). The modal and median age were 31.0 years and 25.0 years respectively, interquartile range (0.4-82). Majority of burns (n = 237, 53.9%) had burn surface area ≥ 10%, most burns were 2nd degree (n = 215, 48.9) and the commonest burn agents were flames (n = 170, 37.3%), electricity (n = 119, 26.3%) and water (n = 114, 25.2%). The paucity of data on burn mortality in Cameroon motivated this study and is aimed at determining the mortality rate, causes and factors associated with death of burnt patients in the burn unit of the Douala General Hospital (DGH).

METHODS

It was a retrospective observational study carried out from the 1st of January 2008 to the 31st of December 2015 in the Burn Unit of the Douala General Hospital. An adapted questionnaire was used to collect demographic data, burn agents, burn depth; diagnostic delay, burn surface area, complications, comorbidity, mortality and its causes. Data was transferred to Microsoft Excel 2015 and the Statistical Package for Social Sciences (SPSS) version 20.0 for data analysis.

RESULTS

During this 8 year period, 440 patients were studied and the mortality rate was 23.4% (103 patients). The fatal burn agents were, flames (n = 69, 67.0%), electricity (n = 15, 14.6%), water (n = 12, 11.6%), contact (n = 4, 3.9%), Oil (n = 2, 1.9%) and chemicals (n = 1, 1.0%). The causes of death were shock (n = 36, 35.0%), sepsis (n = 25, 24.3%), acute respiratory distress (n = 25, 24.3%), acute renal failure (n = 6, 5.8%), severe anaemia (n = 4, 3.9%) and unrecorded causes (n = 7, 6.7%).

CONCLUSION

A quarter of all patients died mostly from flame burns and to a lesser extent, electricity and scalds. Increase in burn depth and burn surface area worsened the prognosis. Shock (the commonest cause of death), sepsis, acute respiratory distress, acute renal failure and wound infection were significantly associated with mortality.