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Topics in Antiviral Medicine ; 30(1 SUPPL):331-332, 2022.
Article in English | EMBASE | ID: covidwho-1880280

ABSTRACT

Background: SARS-CoV2 antibody testing is an important auxillary test especially for retrospective diagnosis or in patients with long COVID-19 or multisystem inflammatory syndrome of childhood. Epidemiological serology studies may also assist public health planning. Access to formal laboratory testing is not universal in many low-and middle-income (LMIC) countries and rapid lateral flow antibody tests are an attractive alternative. Performance of these tests has been inconsistent. A large-scale study was undertaken in South Africa, during the beta and delta waves, to assess the field-based performance of rapid point of care (POC) COVID-19 antibody tests. Methods: Symptomatic, ambulatory persons under investigation (PUIs) aged 18 years and older, presenting for SARS-CoV-2 diagnosis at public health facilities in three provinces, South Africa were enrolled at baseline. All patients completed a questionnaire regarding symptoms. Nasopharyngeal swabs were taken and processed for SARS-CoV-2 PCR testing using a GeneXpert (Cepheid, USA), or manual assay (ThermoFisher TaqPath assay or Seegene Allplex assay) on a real-time platform at routine accredited National Health Laboratory Service laboratories as per routine national protocols. Concomitantly, trained study staff performed three facility-based POC lateral flow antibody tests on a on a fingerstick sample and blood was collected for formal serology. POC tests were selected following a rapid in-laboratory evaluation. Asymptomatic contacts of people with confirmed COVID-19 were recruited into the asymptomatic study arm and rapid tests and PCR were performed. PCR and rapid positive patients and 500 negative controls were followed up at 5-14 days. Antibody tests were compared with formal serology performed on 2 platforms-Euroimmun (Euroimmun, Lubeck) IgA and IgG anti-S antibodies and Abbott Architect IgG test. Results: The sensitivity (S), specificity (Sp), positive (PPV) and negative predictive (NPV) values of tests for PUIs and contacts were calculated (Table 1)∗. Analyses using serology as a reference are forthcoming. Conclusion: Compared with PCR, performance of rapid POC COVID-19 antibody tests was poor with low sensitivity. This may reflect the patient cohort tested as humoral responses typically develop from day 7-14. The tests are unlikely to be useful for acute diagnosis but sensitivity may improve at later timepoints and further follow up data will be analysed by duration of symptom onset, severity of symptoms and wave (beta versus delta).

2.
Topics in Antiviral Medicine ; 30(1 SUPPL):331, 2022.
Article in English | EMBASE | ID: covidwho-1880279

ABSTRACT

Background: Access to SARS-CoV-2 polymerase chain reaction (PCR) testing is a bottleneck globally, especially in low-and middle-income countries (LMICs). Reliable point-of-care (POC) diagnostics for coronavirus disease 2019 (COVID-19) are cheaper and easier to scale-up than PCR especially in LMICs, and will facilitate interruption of transmission. We report the field-based effectiveness of rapid point-of-care (POC) antigen COVID-19 tests during the beta and delta waves, in South Africa. Methods: We enrolled symptomatic, ambulatory persons under investigation (PUIs) aged 18 years and older, presenting for SARS-CoV-2 diagnosis at public health facilities in three provinces, South Africa. All patients completed a questionnaire regarding symptoms. Nasopharyngeal swabs were taken and processed for SARS-CoV-2 PCR testing using either GeneXpert (Cepheid, USA), or with a manual assay (ThermoFisher TaqPath assay or Seegene Allplex assay) on a real-time PCR platform at routine, accredited National Health Laboratory Service laboratories, as per routine national protocols. Concomitantly, trained study staff performed three facility-based POC antigen tests on a nasal/nasopharyngeal swab, as recommended by the manufacturer. Asymptomatic contacts of people with confirmed COVID-19 were recruited into the asymptomatic study arm and rapid tests and PCR were performed. The sensitivity (S), specificity (Sp), positive (PPV) and negative predictive (NPV) values of tests for PUIs and contacts were calculated using PCR as the reference standard. Results: Between Oct 2020-2021 1816 participants were enrolled;472 (26%) tested PCR or rapid test positive;235 positives (49.8%) and 532 negatives were followed up at 5-14 days;574 asymptomatic contacts were enrolled, of which 21 (3.7%) were PCR positive. Performance of the three antigen tests are shown in Table 1∗. Conclusion: In a real world setting, during the beta and delta waves, compared with PCR the sensitivity of rapid antigen tests ranged from 35-68%. This may reflect low viral loads at diagnosis. Further work will compare antigen test performance in patients with high versus lower cycle threshold (Ct) values. Meanwhile, PCR testing capacity needs urgent scale-up in LMICs and improved POC diagnostics are needed to facilitate COVID-19 diagnosis in LMICs.

3.
Embase;
Preprint in English | EMBASE | ID: ppcovidwho-326929

ABSTRACT

Background We conducted a seroepidemiological survey from October 22 to December 9, 2021, in Gauteng Province, South Africa, to determine SARS-CoV-2 immunoglobulin G (IgG) seroprevalence primarily prior to the fourth wave of coronavirus disease 2019 (Covid-19), in which the B.1.1.529 (Omicron) variant is dominant. We evaluated epidemiological trends in case rates and rates of severe disease through to December 15, 2021, in Gauteng. Methods We contacted households from a previous seroepidemiological survey conducted from November 2020 to January 2021, plus an additional 10% of households using the same sampling framework. Dry blood spot samples were tested for anti-spike and anti-nucleocapsid protein IgG using quantitative assays on the Luminex platform. Daily case and death data, weekly excess deaths, and weekly hospital admissions were plotted over time. Results Samples were obtained from 7010 individuals, of whom 1319 (18.8%) had received a Covid-19 vaccine. Overall seroprevalence ranged from 56.2% (95% confidence interval [CI], 52.6 to 59.7) in children aged <12 years to 79.7% (95% CI, 77.6 to 81.5) in individuals aged >50 years. Seropositivity was 6.22-fold more likely in vaccinated (93.1%) vs unvaccinated (68.4%) individuals. Epidemiological data showed SARS-CoV-2 infection rates increased more rapidly than in previous waves but have now plateaued. Rates of hospitalizations and excess deaths did not increase proportionately, remaining relatively low. Conclusions We demonstrate widespread underlying SARS-CoV-2 seropositivity in Gauteng Province prior to the current Omicron-dominant wave, with epidemiological data showing an uncoupling of hospitalization and death rates from infection rate during Omicron circulation.

4.
Bergeri, I.; Whelan, M.; Ware, H.; Subissi, L.; Nardone, A.; Lewis, H. C.; Li, Z.; Ma, X.; Valenciano, M.; Cheng, B.; Ariqi, L. A.; Rashidian, A.; Okeibunor, J.; Azim, T.; Wijesinghe, P.; Le, L. V.; Vaughan, A.; Pebody, R.; Vicari, A.; Yan, T.; Yanes-Lane, M.; Cao, C.; Cheng, M. P.; Papenburg, J.; Buckeridge, D.; Bobrovitz, N.; Arora, R. K.; van Kerkhove, M. D.; Al-Shoteri, S.; Aly, E. A.; Audu, R. A.; Barakat, A.; Bin-Ghouth, A. S.; Birru, E.; Bokonjic, D.; Bolotin, S.; Boucher, E. L.; Catovic-Baralija, E.; Ceban, A.; Chauma-Mwale, A.; Chimeddorj, B.; Chung, P. S.; Clifton, D.; Dabakuyo-Yonli, T. S.; Deveaux, G. R.; Diop, B.; Dokubo, E. K.; Donnici, C.; Duarte, N.; Duarte, N. A.; Evans, T. G.; Fairlie, L.; Freidl, G. S.; Harris, T. G.; Herring, B. L.; Iamsirithaworn, S.; Ila, R.; Ilincic, N.; Ilori, E. A.; Inbanathan, F. Y.; Indenbaum, V.; Kaldor, J.; Kim, D.; Kolawole, O. M.; Kondwani, J. C.; Kuchuk, T.; Lalwani, P. J.; Laman, M.; Lavu, E.; Leite, J.; Liu, M.; Loeschnik, E.; Macartney, K.; Machalek, D. A.; Makiala-Mandanda, S.; Mallet, H. P.; Mapira, P.; Mawien, P. N.; Misra, P.; Musa, S.; Mutevedzi, P. C.; Najjar, O. A.; Nakphook, S.; Noel, K. C.; Nurmatov, Z.; Ome-Kaius, M.; Paudel, K. P.; Perlman-Arrow, S.; Qaddomi, S. E.; Quan, H.; Rady, A.; Rahim, H. P.; Rayyan, I. Y.; Rodriguez, A.; Sachathep, K.; Segal, M.; Selemon, A.; Shirin, T.; Stafford, K. A.; Steinhardt, L.; Tran, V.; Traore, I. T.; Wahyono, T. Y. M.; Williamson, T.; Wood, N.; Yansouni, C. P.; Zhang, C.; Lin, C. Z..
Embase;
Preprint in English | EMBASE | ID: ppcovidwho-326828

ABSTRACT

Background COVID-19 case data underestimates infection and immunity, especially in low- and middle-income countries (LMICs). We meta-analyzed standardized SARS-CoV-2 seroprevalence studies to estimate global seroprevalence. Objectives/Methods We conducted a systematic review and meta-analysis, searching MEDLINE, Embase, Web of Science, preprints, and grey literature for SARS-CoV-2 seroprevalence studies aligned with the WHO UNITY protocol published between 2020-01-01 and 2021-10-29. Eligible studies were extracted and critically appraised in duplicate. We meta-analyzed seroprevalence by country and month, pooling to estimate regional and global seroprevalence over time;compared seroprevalence from infection to confirmed cases to estimate under-ascertainment;meta-analyzed differences in seroprevalence between demographic subgroups;and identified national factors associated with seroprevalence using meta-regression. PROSPERO: CRD42020183634. Results We identified 396 full texts reporting 736 distinct seroprevalence studies (41% LMIC), including 355 low/moderate risk of bias studies with national/sub-national scope in further analysis. By April 2021, global SARS-CoV-2 seroprevalence was 26.1%, 95% CI [24.6-27.6%]. Seroprevalence rose steeply in the first half of 2021 due to infection in some regions (e.g., 18.2% to 45.9% in Africa) and vaccination and infection in others (e.g., 11.3% to 57.4% in the Americas high-income countries), but remained low in others (e.g., 0.3% to 1.6% in the Western Pacific). In 2021 Q1, median seroprevalence to case ratios were 1.9:1 in HICs and 61.9:1 in LMICs. Children 0-9 years and adults 60+ were at lower risk of seropositivity than adults 20-29. In a multivariate model using data pre-vaccination, more stringent public health and social measures were associated with lower seroprevalence. Conclusions Global seroprevalence has risen considerably over time and with regional variation, however much of the global population remains susceptible to SARS-CoV-2 infection. True infections far exceed reported COVID-19 cases. Standardized seroprevalence studies are essential to inform COVID-19 control measures, particularly in resource-limited regions.

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