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Two-Dose Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Effectiveness With Mixed Schedules and Extended Dosing Intervals: Test-Negative Design Studies From British Columbia and Quebec, Canada.
Skowronski, Danuta M; Febriani, Yossi; Ouakki, Manale; Setayeshgar, Solmaz; El Adam, Shiraz; Zou, Macy; Talbot, Denis; Prystajecky, Natalie; Tyson, John R; Gilca, Rodica; Brousseau, Nicholas; Deceuninck, Geneviève; Galanis, Eleni; Fjell, Chris D; Sbihi, Hind; Fortin, Elise; Barkati, Sapha; Sauvageau, Chantal; Naus, Monika; Patrick, David M; Henry, Bonnie; Hoang, Linda M N; De Wals, Philippe; Garenc, Christophe; Carignan, Alex; Drolet, Mélanie; Jassem, Agatha N; Sadarangani, Manish; Brisson, Marc; Krajden, Mel; De Serres, Gaston.
  • Skowronski DM; BC Centre for Disease Control, Communicable Diseases and Immunization Services, Vancouver, British Columbia, Canada.
  • Febriani Y; University of British Columbia, School of Population and Public Health, Vancouver, British Columbia, Canada.
  • Ouakki M; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Setayeshgar S; Institut National de Sante Publique du Québec, Biological and Occupational Risks, Quebec City, Quebec, Canada.
  • El Adam S; BC Centre for Disease Control, Communicable Diseases and Immunization Services, Vancouver, British Columbia, Canada.
  • Zou M; BC Centre for Disease Control, Communicable Diseases and Immunization Services, Vancouver, British Columbia, Canada.
  • Talbot D; BC Centre for Disease Control, Data and Analytics Services, Vancouver, British Columbia, Canada.
  • Prystajecky N; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Tyson JR; Laval University, Department of Social and Preventive Medicine, Faculty of Medicine, Quebec City, Quebec, Canada.
  • Gilca R; BC Centre for Disease Control, Public Health Laboratory, Vancouver, British Columbia, Canada.
  • Brousseau N; University of British Columbia, Department of Pathology and Laboratory Medicine, Vancouver, British Columbia, Canada.
  • Deceuninck G; BC Centre for Disease Control, Public Health Laboratory, Vancouver, British Columbia, Canada.
  • Galanis E; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Fjell CD; Institut National de Sante Publique du Québec, Biological and Occupational Risks, Quebec City, Quebec, Canada.
  • Sbihi H; Laval University, Department of Social and Preventive Medicine, Faculty of Medicine, Quebec City, Quebec, Canada.
  • Fortin E; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Barkati S; Institut National de Sante Publique du Québec, Biological and Occupational Risks, Quebec City, Quebec, Canada.
  • Sauvageau C; Laval University, Department of Social and Preventive Medicine, Faculty of Medicine, Quebec City, Quebec, Canada.
  • Naus M; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Patrick DM; BC Centre for Disease Control, Communicable Diseases and Immunization Services, Vancouver, British Columbia, Canada.
  • Henry B; University of British Columbia, School of Population and Public Health, Vancouver, British Columbia, Canada.
  • Hoang LMN; BC Centre for Disease Control, Public Health Laboratory, Vancouver, British Columbia, Canada.
  • De Wals P; University of British Columbia, School of Population and Public Health, Vancouver, British Columbia, Canada.
  • Garenc C; BC Centre for Disease Control, Data and Analytics Services, Vancouver, British Columbia, Canada.
  • Carignan A; Institut National de Sante Publique du Québec, Biological and Occupational Risks, Quebec City, Quebec, Canada.
  • Drolet M; Laval University, Department of Social and Preventive Medicine, Faculty of Medicine, Quebec City, Quebec, Canada.
  • Jassem AN; Université de Montréal, Département de Microbiologie, Infectiologie et Immunologie, Montreal, Quebec, Canada.
  • Sadarangani M; McGill University, Department of Medicine, Division of Infectious Diseases, McGill University Health Center, Montreal, Quebec, Canada.
  • Brisson M; Centre Hospitalier Universitaire (CHU) de Québec-Université Laval Research Center, Quebec City, Quebec, Canada.
  • Krajden M; Institut National de Sante Publique du Québec, Biological and Occupational Risks, Quebec City, Quebec, Canada.
  • De Serres G; Laval University, Department of Social and Preventive Medicine, Faculty of Medicine, Quebec City, Quebec, Canada.
Clin Infect Dis ; 75(11): 1980-1992, 2022 Nov 30.
Article in English | MEDLINE | ID: covidwho-1927303
ABSTRACT

BACKGROUND:

The Canadian coronavirus disease 2019 (COVID-19) immunization strategy deferred second doses and allowed mixed schedules. We compared 2-dose vaccine effectiveness (VE) by vaccine type (mRNA and/or ChAdOx1), interval between doses, and time since second dose in 2 of Canada's larger provinces.

METHODS:

Two-dose VE against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or hospitalization among adults ≥18 years, including due to Alpha, Gamma, and Delta variants of concern (VOCs), was assessed ≥14 days postvaccination by test-negative design studies separately conducted in British Columbia and Quebec, Canada, between 30 May and 27 November (epi-weeks 22-47) 2021.

RESULTS:

In both provinces, all homologous or heterologous mRNA and/or ChAdOx1 2-dose schedules were associated with ≥90% reduction in SARS-CoV-2 hospitalization risk for ≥7 months. With slight decline from a peak of >90%, VE against infection was ≥80% for ≥6 months following homologous mRNA vaccination, lower by ∼10% when both doses were ChAdOx1 but comparably high following heterologous ChAdOx1 + mRNA receipt. Findings were similar by age group, sex, and VOC. VE was significantly higher with longer 7-8-week versus manufacturer-specified 3-4-week intervals between mRNA doses.

CONCLUSIONS:

Two doses of any mRNA and/or ChAdOx1 combination gave substantial and sustained protection against SARS-CoV-2 hospitalization, spanning Delta-dominant circulation. ChAdOx1 VE against infection was improved by heterologous mRNA series completion. A 7-8-week interval between first and second doses improved mRNA VE and may be the optimal schedule outside periods of intense epidemic surge. Findings support interchangeability and extended intervals between SARS-CoV-2 vaccine doses, with potential global implications for low-coverage areas and, going forward, for children.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Experimental Studies / Observational study / Prognostic study Topics: Vaccines / Variants Limits: Adult / Child / Humans Country/Region as subject: North America Language: English Journal: Clin Infect Dis Journal subject: Communicable Diseases Year: 2022 Document Type: Article Affiliation country: Cid

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Full text: Available Collection: International databases Database: MEDLINE Main subject: SARS-CoV-2 / COVID-19 Type of study: Experimental Studies / Observational study / Prognostic study Topics: Vaccines / Variants Limits: Adult / Child / Humans Country/Region as subject: North America Language: English Journal: Clin Infect Dis Journal subject: Communicable Diseases Year: 2022 Document Type: Article Affiliation country: Cid