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1.
Viruses ; 14(11)2022 Oct 31.
Article in English | MEDLINE | ID: covidwho-2099850

ABSTRACT

BACKGROUND: Investigating antibody titers in individuals who have been both naturally infected with SARS-CoV-2 and vaccinated can provide insight into antibody dynamics and correlates of protection over time. METHODS: Human coronavirus (HCoV) IgG antibodies were measured longitudinally in a prospective cohort of qPCR-confirmed, COVID-19 recovered individuals (k = 57) in British Columbia pre- and post-vaccination. SARS-CoV-2 and endemic HCoV antibodies were measured in serum collected between Nov. 2020 and Sept. 2021 (n = 341). Primary analysis used a linear mixed-effects model to understand the effect of single dose vaccination on antibody concentrations adjusting for biological sex, age, time from infection and vaccination. Secondary analysis investigated the cumulative incidence of high SARS-CoV-2 anti-spike IgG seroreactivity equal to or greater than 5.5 log10 AU/mL up to 105 days post-vaccination. No re-infections were detected in vaccinated participants, post-vaccination by qPCR performed on self-collected nasopharyngeal specimens. RESULTS: Bivariate analysis (complete data for 42 participants, 270 samples over 472 days) found SARS-CoV-2 spike and RBD antibodies increased 14-56 days post-vaccination (p < 0.001) and vaccination prevented waning (regression coefficient, B = 1.66 [95%CI: 1.45-3.46]); while decline of nucleocapsid antibodies over time was observed (regression coefficient, B = -0.24 [95%CI: -1.2-(-0.12)]). A positive association was found between COVID-19 vaccination and endemic human ß-coronavirus IgG titer 14-56 days post vaccination (OC43, p = 0.02 & HKU1, p = 0.02). On average, SARS-CoV-2 anti-spike IgG concentration increased in participants who received one vaccine dose by 2.06 log10 AU/mL (95%CI: 1.45-3.46) adjusting for age, biological sex, and time since infection. Cumulative incidence of high SARS-CoV-2 spike antibodies (>5.5 log10 AU/mL) was 83% greater in vaccinated compared to unvaccinated individuals. CONCLUSIONS: Our study confirms that vaccination post-SARS-CoV-2 infection provides multiple benefits, such as increasing anti-spike IgG titers and preventing decay up to 85 days post-vaccination.


Subject(s)
COVID-19 , Humans , COVID-19/prevention & control , Antibody Formation , SARS-CoV-2 , Prospective Studies , COVID-19 Vaccines , Antibodies, Viral , Vaccination , Immunoglobulin G
2.
5th International Conference on Education and E-Learning, ICEEL 2021 ; : 142-148, 2021.
Article in English | Scopus | ID: covidwho-1731325

ABSTRACT

This paper examines the impact of learning environments, educators’ attention, and students’ personal qualities on the outcomes of online learning. To approach conclusions, this paper describes the heterogeneous effect of these three types of factors on online learning outcomes and employs a fixed-effect regression to examine what exact factors constitute a good learning environment, appropriate educators’ attention and personal qualities that benefit students’ learning efficiency. The fixed-effect regression is applied on data of students’ answers to questionnaires and their final exam scores collected anonymously at three high schools in northern China during COVID-19 quarantine periods when Chinese high schools all conduct lessons and mid-term exams online but the final exam off-line, which is a major differentiation factor of this study. This paper contributes to three major findings: students who are more self-disciplined benefit more from the improvement of learning environments, practicing sports regularly improves online learning outcomes, and educators should find a balance between ensuring students are focused and not giving students too much pressure. © 2021 Association for Computing Machinery.

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