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1.
Mmwr-Morbidity and Mortality Weekly Report ; 71(36):1151-1154, 2022.
Article in English | Web of Science | ID: covidwho-2068408

ABSTRACT

What is already known about this topic? Before emergence of the SARS-CoV-2 B.1.1.529 (Omicron) variant, infectious SARS-CoV-2 was unlikely to be cultured at high cycle threshold (Ct) values. Based on this, low Ct values, which are suggestive of high RNA levels, are sometimes used as surrogate markers for infectiousness. What is added by this report? In a longitudinal study including daily nasal swabbing, although Omicron BA.1 sublineage infections exhibited higher Ct values than did pre-Omicron infections, culturable Omicron virus was still detected. Among virus-positive specimens, Ct values were higher for Omicron than for pre-Omicron specimens, especially during the first week of illness. What are the implications for public health practice? Supporting CDC guidance, these data show that Ct values likely do not provide a consistent proxy for infectiousness across SARS-CoV-2 variants.

2.
Mmwr-Morbidity and Mortality Weekly Report ; 71(21):713-717, 2022.
Article in English | Web of Science | ID: covidwho-1885116
4.
Open Forum Infectious Diseases ; 8(SUPPL 1):S805-S806, 2021.
Article in English | EMBASE | ID: covidwho-1746279

ABSTRACT

Background. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection elicits antibodies (Abs) that bind several viral proteins such as the spike entry protein and the abundant nucleocapsid (N) protein. We examined convalescent sera collected through 6 months (~24wks) post-SARS-CoV-2 infection in children to evaluate changes in neutralization potency and N-binding. Methods. Outpatient, hospitalized, and community recruited volunteers < 18 years with COVID-19 were enrolled in a longitudinal study at Seattle Children's Hospital. Analysis includes symptomatic and asymptomatic children with laboratory-confirmed SARS-CoV-2 infection who provided blood samples at approximately 4wks (range: 2-18wks, IQR:4-8wks) and 24 wks (range: 23-35wks, IQR:25-27wks) after diagnosis. We measured neutralizing Ab using an in-house pseudoneutralization assay and anti-N binding Ab using the Abbott Architect assay. Results. Of 32 children enrolled between April 2020 and January 2021, 27 had no underlying immunocompromised state and 25 of these 27 children had symptomatic disease. Ten of 27 had a > 2-fold decrease neutralization titers between 4 and 24wks (most were < 10-fold);12 had < 2-fold change;and 5 had neutralization titers that increased > 2-fold over time (Fig. 1A). All but one of these 27 children had detectable neutralizing activity at 24wks. Anti-N Abs were assessed for 25 children at 4wks and 17 children at 24wks (data pending for 14 samples);all children with paired samples had a > 1.75-fold Abbott index reduction at 24wks, and 5 children had no detectable anti-N Abs by 24wks (Fig. 2A). An additional 5 children with symptomatic disease had complicating immunosuppression or multiple blood transfusions;2 had decreasing neutralizing titers, 2 increased, and 1 had no change (Fig. 1B). Anti-N Abs were undetectable for one child by 24wks (data pending for 4 samples) (Fig. 2B). No participants received COVID-19 vaccine. Conclusion. We show neutralizing Abs wane to a small degree over 24wks post-SARS-CoV-2 infection and remain detectable in most children. In contrast, anti-N Abs decreased, becoming undetectable in some children by 24wks. These findings add to understanding of the natural history of SARS-CoV-2 immunity in children.

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