ABSTRACT
We conducted weekly surveillance for SARS-CoV-2 infection among a sample of households with [≥]1 child aged 0-17 years from selected Utah counties. A Cox proportional hazards model approach was used to calculate infection hazard rate and vaccine effectiveness. Findings show that the recommended primary series of COVID-19 vaccine was effective against circulating variants during a Delta-predominant wave in Utah.
ABSTRACT
BackgroundThe reliability of sequence-based inference of SARS-CoV-2 transmission is not clear. Sequence data from infections among household members can define the expected genomic diversity of a virus along a defined transmission chain. MethodsSARS-CoV-2 cases were identified prospectively among 2,369 participants in 706 households. Specimens with an RT-PCR cycle threshold [≤]30 underwent whole genome sequencing. Intrahost single nucleotide variants (iSNV) were identified at [≥]5% frequency. Phylogenetic trees were used to evaluate the relationship of household and community sequences. ResultsThere were 178 SARS-CoV-2 cases in 706 households. Among 147 specimens sequenced, 106 yielded a whole genome consensus with coverage suitable for identifying iSNV. Twenty-six households had sequences from multiple cases within 14 days. Consensus sequences were indistinguishable among cases in 15 households, while 11 had [≥]1 consensus that differed by 1-2 mutations. Sequences from households and the community were often interspersed on phylogenetic trees. Identification of iSNV improved inference in 2 of 15 households with indistinguishable consensus sequences and 6 of 11 with distinct ones. ConclusionsIn multiple infection households, whole genome consensus sequences differed by 0-1 mutations. Identification of shared iSNV occasionally resolved linkage, but the low genomic diversity of SARS-CoV-2 limits the utility of "sequence-only" transmission inference. SummaryHigh depth of coverage whole genome sequencing can identify SARS-CoV-2 transmission chains in settings where there is strong epidemiologic linkage but is not reliable as a stand-alone method for transmission inference.
ABSTRACT
During the SARS-CoV-2 pandemic, multiple variants with differing amounts of escape from pre-existing immunity have emerged, causing concerns about continued protection. Here, we use antigenic cartography to quantify and visualize the antigenic relationships among 16 SARS-CoV-2 variants titrated against serum samples taken post-vaccination and post-infection with seven different variants. We find major antigenic differences caused by substitutions at spike positions 417, 452, 484, and possibly 501. B.1.1.529 (Omicron BA.1) showed the highest escape from all sera tested. Visualization of serological responses as antibody landscapes shows how reactivity clusters in different regions of antigenic space. We find changes in immunodominance of different spike regions depending on the variant an individual was exposed to, with implications for variant risk assessment and vaccine strain selection. One sentence summaryAntigenic Cartography of SARS-CoV-2 variants reveals amino acid substitutions governing immune escape and immunodominance patterns.
ABSTRACT
SARS-CoV-2 infections are frequently milder in children than adults, suggesting that immune responses may vary with age. However, information is limited regarding SARS-CoV-2 immune responses in young children. We compared Receptor Binding Domain binding antibody (RBDAb) and SARS-CoV-2 neutralizing antibody (neutAb) in children aged 0-4 years, 5-17 years, and in adults aged 18-62 years in a SARS-CoV-2 household study. Among 55 participants seropositive at enrollment, children aged 0-4 years had >10-fold higher RBDAb titers than adults (373 vs.35, P<0.0001), and the highest RBDAb titers in 11/12 households with seropositive children and adults. Children aged 0-4 years had 2-fold higher neutAb than adults, resulting in higher binding to neutralizing (B/N)Ab ratios compared to adults (1.9 vs. 0.4 for ID50, P=0.0002). Findings suggest that young children mount robust antibody responses to SARS-CoV-2 following community infections. Additionally, these results support using neutAb to measure the immunogenicity of COVID-19 vaccines in children aged 0-4 years.
ABSTRACT
ObjectiveEvaluate pregnant womens attitudes toward COVID-19 illness and vaccination and identify factors associated with vaccine acceptability. Study DesignCross-sectional survey among pregnant women enrolled in a prospective COVID-19 cohort study in Salt Lake City, UT, Birmingham, AL, and New York, NY, August 9- December 10, 2020. Women were eligible if they were 18-50 years old and <28 weeks of gestation. Upon enrollment, women completed surveys regarding concerns about COVID-19 illness and likelihood of getting COVID-19 vaccine if one were available during pregnancy. Vaccine acceptability was defined as a response of "very likely" or "somewhat likely" on a 4-point Likert scale. Factors associated with vaccine acceptability were assessed with multivariable logistic regression. ResultsOf 939 pregnant women eligible for the main cohort study, 915 (97%) consented to participate. Among these 915 women, 39% self-identified as White, 23% Black, 33% Hispanic, and 4% Other. Sixty-two percent received an influenza vaccine last season. Seventy-two percent worried about getting sick with COVID-19. If they were to get sick, 92% worried about harm to their pregnancy and 80% about harm to themselves. Only 41% reported they would get a vaccine. Of women who were unlikely to get vaccinated, the most frequently cited concern was vaccine safety for their pregnancy (82%). Non-Hispanic Black and Hispanic women had lower odds of accepting a vaccine compared with non-Hispanic White women (adjusted odds ratios (aOR) 0.4, 95%CI 0.2-0.6 for both). Receipt of influenza vaccine during the previous season was associated with higher odds of vaccine acceptability (aOR 2.1, 95%CI 1.5-3.0). ConclusionAlthough most pregnant women worried about COVID-19 illness, <50% were willing to get vaccinated during pregnancy. Racial and ethnic disparities in plans to accept COVID-19 vaccine highlight the need to prioritize strategies to address perceived barriers among groups at high risk for COVID-19.
