Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology
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Currently, little is known about the progression of an immune response against SARSCoV- 2 upon infection or sub-infection-exposure over time. We examined the serologic response in healthcare workers up to 12 weeks after a well-documented and contained outbreak and compared results with findings from earlier serologic testing in the same population. ⋯ Immune response after COVID-19 increases significantly over time but still approximately 22 % of COVID-19 patients did not mount a measurable serologic immune response within 60 days. Exposed co-workers did not develop any relevant antibody levels at all. We conclude that immunity after infection increases over time, but the antibody response does not develop reliably in all infected people.
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Comparative Study
Challenges in use of saliva for detection of SARS CoV-2 RNA in symptomatic outpatients.
A major expansion in SARS CoV-2 testing is urgently needed. Saliva is an attractive option as an alternative for nasopharyngeal swabs (NPS), since saliva can be self-collected, is non-invasive, and sample quality is not dependent on the expertise of the collector. ⋯ Real-time RT-PCR of pure saliva had an overall sensitivity for SARS CoV-2 RNA detection of 85.7 % when compared to simultaneously collected NPS. Our study highlighted the need to optimize collection and processing before saliva can be used for high volume testing.
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The MosaiQ® COVID-19 Antibody test fulfills the minimal requirements for serological testing according to the French regulation.
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Commercially available immunoassays have been developed for sensitive and specific detection of antibodies against SARS-CoV-2. While a fast and reliable IgG response has been reported for samples from hospitalized COVID-19 patients, less is known about ambulatory patients. We evaluated the SARS-CoV-2-IgG response by the Anti-SARS-CoV-2-ELISA IgG (Euroimmun) in a defined cohort of SARS-CoV-2-PCR-confirmed outpatients and asymptomatic contact persons including 137 serum samples from PCR-confirmed outpatients (n = 111) and asymptomatic but PCR-positive contact persons (n = 26) sent to our laboratory as part of routine diagnostics for determination of SARS-CoV-2-IgG. ⋯ In contact persons without symptoms the ct values of the PCR assays were significantly higher (5-7 threshold cycles) than in outpatients, and ct values were significantly negative correlated to the SARS-CoV-2-IgG ratio, suggesting a lower viral load as a possible explanation for lower rate of seropositivity. In summary, our study shows that serological response to SARS-CoV-2 in outpatients including asymptomatic persons is less pronounced than in hospitalized patients. Further controlled studies are urgently needed to determine serological response in outpatients and asymptomatic persons since this is the main target population for seroepidemiological investigations.
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Molecular detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is key in the diagnosis of coronavirus disease 2019 (COVID-19) and has been widely used for followup of cases as a proxy for contagiousness. The persistence of SARS-CoV-2 RNA shedding in the context of clinical features and comorbidities is understudied. ⋯ The cumulative CVS rate at 3 weeks from symptom-onset is 44 % in our entire cohort. The findings of our study highlight the low yield of repeating a SARS-CoV-2 NP PCR test within 21 days of a laboratoryconfirmed COVID-19 diagnosis.