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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-335264

ABSTRACT

South Africa’s fourth COVID-19 wave was driven predominantly by three lineages (BA.1, BA.2 and BA.3) of the SARS-CoV-2 Omicron variant of concern. We have now identified two new lineages, BA.4 and BA.5. The spike proteins of BA.4 and BA.5 are identical, and comparable to BA.2 except for the addition of 69-70del, L452R, F486V and the wild type amino acid at Q493. The 69-70 deletion in spike allows these lineages to be identified by the proxy marker of S-gene target failure with the TaqPath™ COVID-19 qPCR assay. BA.4 and BA.5 have rapidly replaced BA.2, reaching more than 50% of sequenced cases in South Africa from the first week of April 2022 onwards. Using a multinomial logistic regression model, we estimate growth advantages for BA.4 and BA.5 of 0.08 (95% CI: 0.07 - 0.09) and 0.12 (95% CI: 0.09 - 0.15) per day respectively over BA.2 in South Africa.

3.
Diagnostics (Basel) ; 12(2)2022 Feb 03.
Article in English | MEDLINE | ID: covidwho-1674534

ABSTRACT

Digital tools can support community-based decentralized testing initiatives to broaden access to COVID-19 diagnosis, especially in high-transmission settings. This operational study investigated the use of antigen-detecting rapid diagnostic tests (Ag-RDTs) for COVID-19 combined with an end-to-end digital health solution, in three taxi ranks in Johannesburg, South Africa. Members of the public were eligible if they were aged ≥18 years, could read, and had a cellphone. Over 15,000 participants, enrolled between June and September 2021, were screened for COVID-19 risk factors. A digital risk questionnaire identified 2061 (13%) participants as moderate risk and 2987 (19%) as high risk, based on symptoms and/or recent exposure to a known case. Of this group referred for testing, 3997 (79%) received Ag-RDTs, with positivity rates of 5.1% in the "high-risk" group and 0.8% in the "moderate-risk" group. A subset of 569 randomly selected participants received additional PCR testing. Sensitivity of the Ag-RDT in this setting was 40% (95% CI: 30.3%, 50.3%); most false negatives had high cycle threshold values (>25), hence low viral loads. Over 80% of participants who tested positive completed a 2-week phone-based follow-up questionnaire. Overall, the digital tool combined with Ag-RDTs enhanced community-based decentralized COVID-19 testing service delivery, reporting and follow-up.

4.
PLoS One ; 17(2): e0262442, 2022.
Article in English | MEDLINE | ID: covidwho-1666757

ABSTRACT

In late December 2019, pneumonia cases of unknown origin were reported in Wuhan, China. This virus was named SARS-CoV2 and the clinical syndrome was named coronavirus disease 19 (COVID-19). South Africa, despite strict and early lockdown has the highest infection rate in Africa. A key component of South Africa's response to SARSCoV2 was the rapid scale-up of diagnostic testing. The Abbott SARS-CoV2 assay detects IgG antibodies against the Nucleocapsid (N) protein of the SARS-CoV2 virus. This study undertook to validate and evaluate performance criteria of the Abbott assay and to establish whether this assay would show clinical utility in our population. Positive patients (n = 391) and negative controls (n = 139) were included. The Architect-i and Alinity-i systems were analyzers that were used to perform the SARS-CoV-2 IgG assay. In-house ELISA was incorporated into the study as a confirmatory serology test. A total of number of 530 participants was tested, 87% were symptomatic with infection and 13% were asymptomatic. When compared to RT-qPCR, the sensitivity of Architect and Alinity SARS-CoV2 assays was 69.5% and 64.8%, respectively. Specificity for Architect and Alinity assays was 95% and 90.3%, respectively. The Abbott assay was also compared to in house ELISA assay, with sensitivity for the Architect and Alinity assays of 94.7% and 92.5%, respectively. Specificity for Abbott Alinity assays was 91.7% higher than Abbott Architect 88.1%. Based on the current findings testing of IgG after 14 days is recommended in South Africa and supports other studies performed around the world.


Subject(s)
Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Immunoglobulin G/blood , SARS-CoV-2/isolation & purification , Adult , Aged , Aged, 80 and over , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/epidemiology , COVID-19/virology , Enzyme-Linked Immunosorbent Assay , Female , Follow-Up Studies , Humans , Immunoglobulin G/immunology , Male , Middle Aged , Prognosis , Retrospective Studies , South Africa/epidemiology , Young Adult
5.
J Virol Methods ; 302: 114471, 2022 04.
Article in English | MEDLINE | ID: covidwho-1638654

ABSTRACT

Routine SARS-CoV-2 surveillance in the Western Cape region of South Africa (January-August 2021) found a reduced RT-PCR amplification efficiency of the RdRp-gene target of the Seegene, Allplex 2019-nCoV diagnostic assay from June 2021 when detecting the Delta variant. We investigated whether the reduced amplification efficiency denoted by an increased RT-PCR cycle threshold value (RΔE) can be used as an indirect measure of SARS-CoV-2 Delta variant prevalence. We found a significant increase in the median RΔE for patient samples tested from June 2021, which coincided with the emergence of the SARS-CoV-2 Delta variant within our sample set. Whole genome sequencing on a subset of patient samples identified a highly conserved G15451A, non-synonymous mutation exclusively within the RdRp gene of Delta variants, which may cause reduced RT-PCR amplification efficiency. While whole genome sequencing plays an important in identifying novel SARS-CoV-2 variants, monitoring RΔE value can serve as a useful surrogate for rapid tracking of Delta variant prevalence.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19/virology , Diagnostic Tests, Routine , Humans , RNA , RNA-Dependent RNA Polymerase , SARS-CoV-2/genetics
7.
J Immunol Methods ; 496: 113096, 2021 09.
Article in English | MEDLINE | ID: covidwho-1349521

ABSTRACT

Serology or antibody tests for COVID-19 are designed to detect antibodies (mainly Immunoglobulin M (IgM) and Immunoglobulin G (IgG) produced in response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS CoV-2) infection. In this study, 30 lateral flow immunoassays were tested using serum or plasma from patients with confirmed SARS CoV-2 infection. Negative serological controls were accessed from a well-characterised bank of sera which were stored prior to February 2020. Operational characteristics and ease of use of the assays are reported. 4/30 (13%) of kits (Zheihang Orient Gene COVID-19 IgG/IgM, Genrui Novel Coronavirus (2019-nCoV) IgG/IgM, Biosynex COVID-19 BSS IgG/IgM, Boson Biotech 2019-nCoV IgG/IgM) were recommended for SAHPRA approval based on kit sensitivity. Of these, only the Orientgene was recommended by SAHPRA in August 2020 for use within the approved national testing algorithm while the remaining three received limited authorization for evaluation. All kits evaluated work on the same basic principle of immunochromatography with minor differences noted in the shape and colour of cartridges, the amount of specimen volume required and the test duration. Performance of the lateral flow tests were similar to sensitivities and specificities reported in other studies. The cassettes of the majority of kits evaluated (90%) detected both IgG and IgM. Only 23% of kits evaluated contained all consumables required for point-of-care testing. The study highlights the need for thorough investigation of kits prior to implementation.


Subject(s)
Antibodies, Viral/isolation & purification , COVID-19 Serological Testing/instrumentation , COVID-19/diagnosis , Immunoassay/instrumentation , Reagent Kits, Diagnostic/statistics & numerical data , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/blood , COVID-19/immunology , COVID-19/virology , COVID-19 Nucleic Acid Testing/statistics & numerical data , COVID-19 Serological Testing/statistics & numerical data , Humans , Immunoassay/statistics & numerical data , Immunoglobulin G/blood , Immunoglobulin G/immunology , Immunoglobulin G/isolation & purification , Immunoglobulin M/blood , Immunoglobulin M/immunology , Immunoglobulin M/isolation & purification , Point-of-Care Testing/statistics & numerical data , RNA, Viral/blood , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Sensitivity and Specificity
8.
PLoS One ; 16(6): e0252317, 2021.
Article in English | MEDLINE | ID: covidwho-1280618

ABSTRACT

Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) has been identified as the causative agent for causing the clinical syndrome of COVID -19. Accurate detection of SARS-CoV-2 infection is not only important for management of infected individuals but also to break the chain of transmission. South Africa is the current epicenter of SARS-CoV-2 infection in Africa. To optimize the diagnostic algorithm for SARS-CoV-2 in the South African setting, the study aims to evaluate the diagnostic performance of the EUROIMMUN Anti-SARS-CoV-2 assays. This study reported the performance of EUROIMMUN enzyme-linked immunosorbent assay (ELISA) for semi-quantitative detection of IgA and IgG antibodies in serum and plasma samples targeting the recombinant S1 domain of the SARS-CoV-2 spike protein as antigen. Samples were collected from 391 individuals who had tested positive for SARS-CoV-2 and 139 SARS CoV-2 negative controls. Samples were stratified by number of days' post-PCR diagnosis and symptoms. The sensitivity of EUROIMMUN IgG was 64.1% (95% CI: 59.1-69.0%) and 74.3% (95% CI: 69.6-78.6%) for IgA and the specificity was lower for IgA [84.2% (95% CI: 77-89.2%)] than IgG [95.2% (95% CI: 90.8-98.4%)]. The EUROIMMUN Anti-SARS-CoV-2 ELISA Assay sensitivity was higher for IgA but low for IgG and improved for both assays in symptomatic individuals and at later timepoints post PCR diagnosis.


Subject(s)
COVID-19 Serological Testing/methods , Immunoglobulin A/blood , Immunoglobulin G/blood , Adult , Aged , Aged, 80 and over , COVID-19 Nucleic Acid Testing/methods , Enzyme-Linked Immunosorbent Assay/methods , Female , Humans , Male , Middle Aged , Point-of-Care Testing , Sensitivity and Specificity , South Africa
9.
JMIR Res Protoc ; 10(5): e24811, 2021 May 28.
Article in English | MEDLINE | ID: covidwho-1256240

ABSTRACT

BACKGROUND: SARS-CoV-2 is a novel coronavirus discovered in December 2019 and is currently the cause of the global COVID-19 pandemic. A critical aspect of fighting this pandemic is to obtain accurate and timely test results so that patients who have tested positive for COVID-19 can be identified and isolated to reduce the spread of the virus. Research has shown that saliva is a promising candidate for SARS-CoV-2 diagnostics because its collection is minimally invasive and can be reliably self-administered. However, little research has been conducted on saliva testing and SARS-CoV-2 self-sampling (SARS-CoV-2SS) in Sub-Saharan Africa. OBJECTIVE: The primary objective of this study is to comparatively evaluate the clinical sensitivity and specificity of nasal and oral samples self-collected by individuals for SARS-CoV-2 testing against a reference method involving sample collection and testing by a health care professional. The secondary objectives of this study are to evaluate the usability of nasal self-sampling and saliva self-sampling as a sample collection method for SARS-CoV-2 diagnostic testing by using failure mode and error assessment. METHODS: Participants will be recruited from the general population by using various methods, Participants will be screened progressively as they present at the clinical trial sites as well as in primary health care catchment areas in the inner city of Johannesburg, South Africa. In the event that recruitment numbers are low, we will use a mobile van to recruit participants from outlying areas of Johannesburg. We aim to enroll 250 participants into this study in approximately 6 weeks. Two sample types-a self-administered nasal swab and a self-administered saliva sample-will be collected from each participant, and a health care professional will collect a third sample by using a nasopharyngeal swab (ie, the standard reference method). RESULTS: This protocol has been approved by the University of the Witwatersrand Human Research Ethics Committee on July 31, 2020 (Protocol number EzCov003). As of May 13, 2021, 120 participants have been enrolled into the study. CONCLUSIONS: SARS-CoV-2SS may offer many benefits to individuals, by allowing for initial self-identification of symptoms and collection of samples without involving third parties and potential risk of infection provided the sample can be safely processed via a collection system. The results of this study will provide preliminary data on the acceptability, feasibility, and usability of SARS-CoV-2SS among the general population for its future implementation. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/24811.

10.
JMIR Res Protoc ; 10(5): e24811, 2021 May 28.
Article in English | MEDLINE | ID: covidwho-1197470

ABSTRACT

BACKGROUND: SARS-CoV-2 is a novel coronavirus discovered in December 2019 and is currently the cause of the global COVID-19 pandemic. A critical aspect of fighting this pandemic is to obtain accurate and timely test results so that patients who have tested positive for COVID-19 can be identified and isolated to reduce the spread of the virus. Research has shown that saliva is a promising candidate for SARS-CoV-2 diagnostics because its collection is minimally invasive and can be reliably self-administered. However, little research has been conducted on saliva testing and SARS-CoV-2 self-sampling (SARS-CoV-2SS) in Sub-Saharan Africa. OBJECTIVE: The primary objective of this study is to comparatively evaluate the clinical sensitivity and specificity of nasal and oral samples self-collected by individuals for SARS-CoV-2 testing against a reference method involving sample collection and testing by a health care professional. The secondary objectives of this study are to evaluate the usability of nasal self-sampling and saliva self-sampling as a sample collection method for SARS-CoV-2 diagnostic testing by using failure mode and error assessment. METHODS: Participants will be recruited from the general population by using various methods, Participants will be screened progressively as they present at the clinical trial sites as well as in primary health care catchment areas in the inner city of Johannesburg, South Africa. In the event that recruitment numbers are low, we will use a mobile van to recruit participants from outlying areas of Johannesburg. We aim to enroll 250 participants into this study in approximately 6 weeks. Two sample types-a self-administered nasal swab and a self-administered saliva sample-will be collected from each participant, and a health care professional will collect a third sample by using a nasopharyngeal swab (ie, the standard reference method). RESULTS: This protocol has been approved by the University of the Witwatersrand Human Research Ethics Committee on July 31, 2020 (Protocol number EzCov003). As of May 13, 2021, 120 participants have been enrolled into the study. CONCLUSIONS: SARS-CoV-2SS may offer many benefits to individuals, by allowing for initial self-identification of symptoms and collection of samples without involving third parties and potential risk of infection provided the sample can be safely processed via a collection system. The results of this study will provide preliminary data on the acceptability, feasibility, and usability of SARS-CoV-2SS among the general population for its future implementation. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/24811.

11.
Front Plant Sci ; 12: 589940, 2021.
Article in English | MEDLINE | ID: covidwho-1191775

ABSTRACT

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has swept the world and poses a significant global threat to lives and livelihoods, with 115 million confirmed cases and at least 2.5 million deaths from Coronavirus disease 2019 (COVID-19) in the first year of the pandemic. Developing tools to measure seroprevalence and understand protective immunity to SARS-CoV-2 is a priority. We aimed to develop a serological assay using plant-derived recombinant viral proteins, which represent important tools in less-resourced settings. Methods: We established an indirect ELISA using the S1 and receptor-binding domain (RBD) portions of the spike protein from SARS-CoV-2, expressed in Nicotiana benthamiana. We measured antibody responses in sera from South African patients (n = 77) who had tested positive by PCR for SARS-CoV-2. Samples were taken a median of 6 weeks after the diagnosis, and the majority of participants had mild and moderate COVID-19 disease. In addition, we tested the reactivity of pre-pandemic plasma (n = 58) and compared the performance of our in-house ELISA with a commercial assay. We also determined whether our assay could detect SARS-CoV-2-specific IgG and IgA in saliva. Results: We demonstrate that SARS-CoV-2-specific immunoglobulins are readily detectable using recombinant plant-derived viral proteins, in patients who tested positive for SARS-CoV-2 by PCR. Reactivity to S1 and RBD was detected in 51 (66%) and 48 (62%) of participants, respectively. Notably, we detected 100% of samples identified as having S1-specific antibodies by a validated, high sensitivity commercial ELISA, and optical density (OD) values were strongly and significantly correlated between the two assays. For the pre-pandemic plasma, 1/58 (1.7%) of samples were positive, indicating a high specificity for SARS-CoV-2 in our ELISA. SARS-CoV-2-specific IgG correlated significantly with IgA and IgM responses. Endpoint titers of S1- and RBD-specific immunoglobulins ranged from 1:50 to 1:3,200. S1-specific IgG and IgA were found in saliva samples from convalescent volunteers. Conclusion: We demonstrate that recombinant SARS-CoV-2 proteins produced in plants enable robust detection of SARS-CoV-2 humoral responses. This assay can be used for seroepidemiological studies and to measure the strength and durability of antibody responses to SARS-CoV-2 in infected patients in our setting.

12.
Diagnostics (Basel) ; 11(2)2021 Jan 22.
Article in English | MEDLINE | ID: covidwho-1052497

ABSTRACT

The tiered laboratory framework for human immunodeficiency virus (HIV) viral load monitoring accommodates a range of HIV viral load testing platforms, with quality assessment critical to ensure quality patient testing. HIV plasma viral load testing is challenged by the instability of viral RNA. An approach using an RNA stabilizing buffer is described for the Xpert® HIV-1 Viral Load (Cepheid) assay and was tested in remote laboratories in South Africa. Plasma panels with known HIV viral titres were prepared in PrimeStore molecular transport medium for per-module verification and per-instrument external quality assessment. The panels were transported at ambient temperatures to 13 testing laboratories during 2017 and 2018, tested according to standard procedures and uploaded to a web portal for analysis. A total of 275 quality assessment specimens (57 verification panels and two EQA cycles) were tested. All participating laboratories met study verification criteria (n = 171 specimens) with an overall concordance correlation coefficient (ρc) of 0.997 (95% confidence interval (CI): 0.996 to 0.998) and a mean bias of -0.019 log copies per milliliter (cp/mL) (95% CI: -0.044 to 0.063). The overall EQA ρc (n = 104 specimens) was 0.999 (95% CI: 0.998 to 0.999), with a mean bias of 0.03 log cp/mL (95% CI: 0.02 to 0.05). These panels are suitable for use in quality monitoring of Xpert® HIV-1 VL and are applicable to laboratories in remote settings.

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