Search

The vaccines presently available are less effective in older people due to senescence of their immune systems. We measured the antibody responses of 42 adults living in nursing homes after the third and the fourth doses of an mRNA vaccine and found that the strain (BA.2 and BA.2.75: from 64 to 128, BA.5: from 16 to 32, BQ.1.1: from 16 to 64 among the uninfected) influenced the effect of the fourth dose of vaccine on neutralizing antibodies. The fourth dose also increased binding antibodies (from 1036 BAU/mL to 5371 BAU/mL among the uninfected, from 3700 BAU/mL to 6773 BAU/mL among the BA.5 infected). This effect was less significant than that of the third dose of vaccine for both neutralizing (BA.2: from 8 to 128, BA.5: from 2 to 16, BA.2.75: from 8 to 64, BQ.1.1: from 2 to 16) and binding antibodies (from 139.8 BAU/mL to 2293 BAU/mL). However, the fourth dose attained the 5000 BAU/mL threshold conferring approximately 80% protection against a SARS-CoV-2 BA.2 infection in most individuals, unlike the third. [ABSTRACT FROM AUTHOR]

The present study aimed to determine whether current commercial immunoassays are adequate for detecting anti‐Omicron antibodies. We analyzed the anti‐SARS‐CoV‐2 antibody response of 23 unvaccinated individuals 1–2 months after an Omicron infection. All blood samples were tested with a live virus neutralization assay using a clinical Omicron BA.1 strain and four commercial SARS‐CoV‐2 immunoassays. We assessed three anti‐Spike immunoassays (SARS‐CoV‐2 IgG II Quant [Abbott S], Wantaï anti‐SARS‐CoV‐2 antibody ELISA [Wantaï], Elecsys Anti‐SARS‐CoV‐2 S assay [Roche]) and one anti‐Nucleocapsid immunoassay (Abbott SARS‐CoV‐2 IgG assay [Abbott N]). Omicron neutralizing antibodies were detected in all samples with the live virus neutralization assay. The detection rate of the Abbott S, Wantai, Roche, and Abbott N immunoassays were 65.2%, 69.6%, 86.9%, and 91.3%, respectively. The sensitivities of Abbott S and Wantai immunoassays were significantly lower than that of the live virus neutralization assay (p = 0.004, p = 0.009; Fisher's exact test). Antibody concentrations obtained with anti‐S immunoassays were correlated with Omicron neutralizing antibody concentrations. These data provide clinical evidence of the loss of performance of some commercial immunoassays to detect antibodies elicited by Omicron infections. It highlights the need to optimize these assays by adapting antigens to the circulating SARS‐CoV‐2 strains. [ABSTRACT FROM AUTHOR]

The article explores how anti–coronavirus disease 2019 (COVID-19) vaccination reduces symptomatic and asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections with information on the relative strengths of the neutralizing antibody responses conferred by vaccination and a natural infection or on the benefit of vaccinating a previously infected person. It mentions that about ongoing studies on the persistence of neutralizing antibodies after a first infection.