ABSTRACT
SARS-CoV-2 transmission occurs even among fully vaccinated individuals; thus, prompt identification of infected patients is central to control viral circulation. Antigen rapid diagnostic tests (Ag-RDT) are highly specific, but sensitivity is variable.Discordant RT-qPCR vs Ag-RDT results are reported, raising the question of whether negative Ag-RDT in positive RT-qPCR samples could imply the absence of infectious viruses. To study the relationship between a negative Ag-RDT results with virological, molecular, and serological parameters, we selected a cross sectional and a follow-up dataset and analyzed virus culture, subgenomic RNA quantification, and sequencing to determine infectious viruses and mutations. We demonstrated that a positive SARS-CoV-2 Ag-RDT result correlates with the presence of infectious virus in nasopharyngeal samples. A decrease in sgRNA detection together with an expected increase in detectable anti-S and anti-N IgGs was verified in negative Ag-RDT / positive RT-qPCR samples. The data clearly demonstrates the less likelihood of a negative Ag-RDT sample to harbor infectious SARS-CoV-2 and consequently with a lower transmissible potential.
ABSTRACT
The Caribbean region is lacking an assessment of the antibody response and side effects experienced after AstraZeneca COVID-19 vaccination (AZD1222). We examined SARS-CoV-2 spike receptor binding domain (RBD) IgG levels and reported side effects in a Jamaican population after AZD1222 vaccination. Median RBD IgG levels for persons without evidence of previous SARS-CoV-2 infection were 43.1 bIU/mL after 3-7 weeks post first dose, rising to 100.1 bIU/mL 3-7 weeks post second dose, and falling 46.9 bIU/mL 16-22 weeks post second dose. The median RBD IgG level 2-8 weeks after symptom onset for unvaccinated SARS-CoV-2 infected persons of all disease severities was 411.6 bIU/mL. Common AZD1222 side effects after first dose were injection site pain, headache and chills. Most persons reported no side effects after second dose. AZD1222 is widely used across the English-speaking Caribbean and the study provides evidence for its continued safe and effective use in vaccination programs.
ABSTRACT
BackgroundViral diversity presents an ongoing challenge for diagnostic tests, which need to accurately detect all circulating variants. The Abbott Global Surveillance program monitors severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants and their impact on diagnostic test performance. ObjectivesTo evaluate the capacity of Abbott molecular, antigen, and serologic assays to detect the SARS-CoV-2 B.1.1.7, B.1.351 and the P.1 variants. Study designVirus variant culture stock dilutions (B.1.1.7, BEI NR-54011; B.1.351, BEI NR-54008 and 54009; P.1, BEI NR-54982) and clinical samples from patients with confirmed B.1.1.7 variant infection were run on the Abbott ID NOW COVID-19, m2000 RealTime SARS-CoV-2, Alinity m SARS-CoV-2, and Alinity m Resp-4-Plex molecular assays; the BinaxNOW COVID-19 Ag Card and Panbio COVID-19 Ag Rapid Test Device; and the ARCHITECT/Alinity i SARS-CoV-2 IgG and AdviseDx IgM assays, Panbio COVID-19 IgG assay, and ARCHITECT/Alinity i AdviseDx SARS-CoV-2 IgG II assay. ResultsCultured virus stocks and B.1.1.7 clinical samples were detected with molecular, antigen, and serologic assays in the expected ranges, confirming in silico predictions. The ratio between genome equivalents (GE) and calculated median tissue culture infectious dose (TCID50) were 31-to 83-fold higher for B.1.1.7 cultures compared to B.1.351 and P.1 cultures, demonstrating that GE are more consistent units between cultures than TCID50. ConclusionsAbbott molecular and antigen assays effectively detect B.1.1.7, B.1.351, and P.1 variant infections and Abbott serologic assays detect B.1.1.7 antibodies in patient sera. Future studies with SARS-CoV-2 virus cultures should use quantitative viral load values to compare detection of variants. HighlightsO_LIAbbott SARS-CoV-2 molecular and antigen assays detect B.1.1.7, B.1.351, and P.1 variants C_LIO_LIAbbott SARS-CoV-2 antibody assays detect B.1.1.7 antibodies in recovered patient sera C_LIO_LIQuantitation of viral load in genome equivalents allows comparison of assay performance C_LI
