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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.
PubMed; 2021.
Preprint in English | PubMed | ID: ppcovidwho-9281

ABSTRACT

Rapidly-emerging variants jeopardize antibody-based countermeasures against SARS-CoV-2. While recent cell culture experiments have demonstrated loss of potency of several anti-spike neutralizing antibodies against SARS-CoV-2 variant strains1-3, the in vivo significance of these results remains uncertain. Here, using a panel of monoclonal antibodies (mAbs) corresponding to many in advanced clinical development by Vir Biotechnology, AbbVie, AstraZeneca, Regeneron, and Lilly we report the impact on protection in animals against authentic SARS-CoV-2 variants including WA1/2020 strains, a B.1.1.7 isolate, and chimeric strains with South African (B.1.351) or Brazilian (B.1.1.28) spike genes. Although some individual mAbs showed reduced or abrogated neutralizing activity against B.1.351 and B.1.1.28 viruses with E484K spike protein mutations in cell culture, low prophylactic doses of mAb combinations protected against infection in K18-hACE2 transgenic mice, 129S2 immunocompetent mice, and hamsters without emergence of resistance. Two exceptions were mAb LY-CoV555 monotherapy which lost all protective activity in vivo, and AbbVie 2B04/47D11, which showed partial loss of activity. When administered after infection as therapy, higher doses of mAb cocktails protected in vivo against viruses displaying a B.1.351 spike gene. Thus, many, but not all, of the antibody products with Emergency Use Authorization should retain substantial efficacy against the prevailing SARS-CoV-2 variant strains.

3.
PubMed; 2021.
Preprint in English | PubMed | ID: ppcovidwho-8845

ABSTRACT

Rapidly-emerging variants jeopardize antibody-based countermeasures against SARS-CoV-2. While recent cell culture experiments have demonstrated loss of potency of several anti-spike neutralizing antibodies against SARS-CoV-2 variant strains1-3, the in vivo significance of these results remains uncertain. Here, using a panel of monoclonal antibodies (mAbs) corresponding to many in advanced clinical development by Vir Biotechnology, AbbVie, AstraZeneca, Regeneron, and Lilly we report the impact on protection in animals against authentic SARS-CoV-2 variants including WA1/2020 strains, a B.1.1.7 isolate, and chimeric strains with South African (B.1.351) or Brazilian (B.1.1.28) spike genes. Although some individual mAbs showed reduced or abrogated neutralizing activity against B.1.351 and B.1.1.28 viruses with E484K spike protein mutations in cell culture, low prophylactic doses of mAb combinations protected against infection in K18-hACE2 transgenic mice, 129S2 immunocompetent mice, and hamsters without emergence of resistance. Two exceptions were mAb LY-CoV555 monotherapy which lost all protective activity in vivo, and AbbVie 2B04/47D11, which showed partial loss of activity. When administered after infection as therapy, higher doses of mAb cocktails protected in vivo against viruses displaying a B.1.351 spike gene. Thus, many, but not all, of the antibody products with Emergency Use Authorization should retain substantial efficacy against the prevailing SARS-CoV-2 variant strains.

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