Search Results for: Ipotesi sull’origine di Omicron e sua evoluzione

Objective
To determine the SARS-CoV-2 seroprevalence among school workers within the Greater Vancouver area, British Columbia, Canada, after the first Omicron wave.

Design
Cross-sectional study by online questionnaire, with blood serology testing.

Setting
Three main school districts (Vancouver, Richmond and Delta) in the Vancouver metropolitan area.

Participants
Active school staff enrolled from January to April 2022, with serology testing between 27 January and 8 April 2022. Seroprevalence estimates were compared with data obtained from Canadian blood donors weighted over the same sampling period, age, sex and postal code distribution.

Primary and secondary outcomes
SARS-CoV-2 nucleocapsid antibody testing results adjusted for test sensitivity and specificity, and regional variation across school districts using Bayesian models.

Results
Of 1850 school staff enrolled, 65.8% (1214/1845) reported close contact with a COVID-19 case outside the household. Of those close contacts, 51.5% (625/1214) were a student and 54.9% (666/1214) were a coworker. Cumulative incidence of COVID-19 positive testing by self-reported nucleic acid or rapid antigen testing since the beginning of the pandemic was 15.8% (291/1845). In a representative sample of 1620 school staff who completed serology testing (87.6%), the adjusted seroprevalence was 26.5% (95% CrI 23.9% to 29.3%), compared with 32.4% (95% CrI 30.6% to 34.5%) among 7164 blood donors.

Conclusion
Despite frequent COVID-19 exposures reported, SARS-CoV-2 seroprevalence among school staff in this setting remained no greater than the community reference group. Results are consistent with the premise that many infections were acquired outside the school setting, even with Omicron.

After increasing in prevalence during the early months of 2023, the Omicron descendent XBB.1.16 is now a variant of interest, the World Health Organization (WHO) announced. XBB.1.16, a combination of 2 BA.2 lineages, accounted for 4.15% of COVID-19 cases worldwide as of the week of March 27, up from 0.52% 4 weeks prior. More than 30 countries have reported XBB.1.16 cases, the majority of which are in India.

Parents who were worried about the long-term risks of the COVID-19 vaccine in children were 6% less likely to have vaccinated their children, according to an internet panel survey of 1715 parents with at least 1 child between the ages of 5 and 17 years. In addition, 18% of surveyed parents said they would feel more responsible if their child became sick after COVID-19 vaccination than if they became sick without vaccination. The survey was performed in February and March 2022, when the SARS-CoV-2 Omicron variant was predominant.

New England Journal of Medicine, Volume 388, Issue 18, Page 1726-1727, May 2023.

Objectives
Healthcare workers (HCWs) were the first to be prioritised for COVID-19 vaccination. This study aims to estimate the COVID-19 vaccine effectiveness (VE) against SARS-CoV-2 symptomatic infection among HCWs in Portuguese hospitals.

Design
Prospective cohort study.

Setting and participants
We analysed data from HCWs (all professional categories) from three central hospitals: one in the Lisbon and Tagus Valley region and two in the central region of mainland Portugal, between December 2020 and March 2022. VE against symptomatic SARS-CoV-2 infection was estimated as one minus the confounder adjusted HRs by Cox models considering age group, sex, self-reported chronic disease and occupational exposure to patients diagnosed with COVID-19 as adjustment variables.

Results
During the 15 months of follow-up, the 3034 HCWs contributed a total of 3054 person-years at risk, and 581 SARS-CoV-2 events occurred. Most participants were already vaccinated with a booster dose (n=2653, 87%), some are vaccinated with only the primary scheme (n=369, 12.6%) and a few remained unvaccinated (n=12, 0.4%) at the end of the study period. VE against symptomatic infection was 63.6% (95% CI 22.6% to 82.9%) for HCWs vaccinated with two doses and 55.9% (95% CI –1.3% to 80.8%) for HCWs vaccinated with one booster dose. Point estimate VE was higher for individuals with two doses taken between 14 days and 98 days (VE=71.9%; 95% CI 32.3% to 88.3%).

Conclusion
This cohort study found a high COVID-19 VE against symptomatic SARS-CoV-2 infection in Portuguese HCWs after vaccination with one booster dose, even after Omicron variant occurrence. The small sample size, the high vaccine coverage, the very low number of unvaccinated individuals and the few events observed during the study period contributed to the low precision of the estimates.

Revised COVID-19 vaccination recommendations reflect the impact of circulating Omicron variants as well as current population immunity due to previous infection and vaccination, according to a statement from the Strategic Advisory Group of Experts on Immunization (SAGE), part of the World Health Organization (WHO).

Commissione al lavoro. D’Ippolito, ‘evitare denunce temerarie’

New England Journal of Medicine, Ahead of Print.

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