High vaccine effectiveness against coronavirus disease 2019 (COVID-19) and severe disease among residents and staff of long-term care facilities in Norway, November 2020–June 2021

Starrfelt, Jostein; Danielsen, Anders Skyrud; Kacelnik, Oliver; Børseth, Anita Wang; Seppälä, Elina; Meijerink, Hinta

doi:10.1017/ash.2021.246

Cited by 6 publications

(3 citation statements)

References 11 publications

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“…Past studies of vaccine effectiveness of two doses of mRNA vaccines in long term care populations conducted earlier in the pandemic have reported higher vaccine effectiveness estimates (71-82%) against infection compared with the estimates we observed for fourth doses. 30 31 However, vaccine effectiveness studies conducted later against predominating variants of concern have reported similar estimates to our fourth dose estimates against the omicron variant; two dose vaccine effectiveness against beta infection in long term care facilities in France was 49% and against delta infection in US facilities was 53%. 12 32 Vaccine effectiveness against omicron, particularly against infection, has also been found to be lower than for any previous variant of concern.…”

Section: Discussionsupporting

confidence: 76%

Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study

Grewal

Kitchen²,

Nguyen³

et al. 2022

BMJ

128

137

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Objectives To estimate the marginal effectiveness of a fourth versus third dose and the vaccine effectiveness of mRNA covid-19 vaccines BNT162b2 and mRNA-1273 against any infection, symptomatic infection, and severe outcomes (hospital admission or death) related to the omicron variant. Design Test negative design. Setting Long term care facilities in Ontario, Canada, 30 December 2021 to 27 April 2022. Participants After exclusions, 61 344 residents aged 60 years or older across 626 long term care facilities in Ontario, Canada who were tested for SARS-CoV-2 were included. Main outcome measures Laboratory confirmed omicron SARS-CoV-2 infection (any and symptomatic) by reverse transcription polymerase chain reaction (RT-PCR), and hospital admission or death. Multivariable logistic regression was used to estimate marginal effectiveness (four versus three doses) and vaccine effectiveness (two, three, or four doses versus no doses) while adjusting for personal characteristics, comorbidities, week of test, and previous positive SARS-CoV-2 test result more than 90 days previously. Results 13 654 residents who tested positive for omicron SARS-CoV-2 infection and 205 862 test negative controls were included. The marginal effectiveness of a fourth dose (95% of vaccine recipients received mRNA-1273 as the fourth dose) seven days or more after vaccination versus a third dose received 84 or more days previously was 19% (95% confidence interval 12% to 26%) against infection, 31% (20% to 41%) against symptomatic infection, and 40% (24% to 52%) against severe outcomes. Vaccine effectiveness in vaccine recipients (compared with unvaccinated) increased with each additional dose, and for a fourth dose was 49% (95% confidence interval 43% to 54%) against infection, 69% (61% to 76%) against symptomatic infection, and 86% (81% to 90%) against severe outcomes. Conclusions The findings suggest that compared with a third dose of mRNA covid-19 vaccine, a fourth dose improved protection against infection, symptomatic infection, and severe outcomes among long term care residents during an omicron dominant period. A fourth vaccine dose was associated with strong protection against severe outcomes in vaccinated residents compared with unvaccinated residents, although the duration of protection remains unknown.

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Section: Discussionsupporting

confidence: 76%

Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study

Grewal

Kitchen²,

Nguyen³

et al. 2022

BMJ

128

137

View full text Add to dashboard Cite

show abstract

“…Past studies of 2-dose mRNA VE in LTC populations conducted earlier in the pandemic have reported higher VE estimates (71-82%) than the VE estimates we observed for fourth doses. 32,33 However, VE studies conducted later against predominating variants of concern (VOC) have reported similar estimates to our fourth dose estimates against Omicron; VE against Beta infection in LTC facilities in France was 49% and against Delta infection in United States (US) facilities was 53%. 12,34 VE against Omicron, particularly against infection, has also been found to be lower than any previous VOC.…”

Section: Discussionsupporting

confidence: 79%

Effectiveness of a Fourth Dose of COVID-19 Vaccine among Long-Term Care Residents in Ontario, Canada: Test-Negative Design Study

Grewal

Kitchen

Nguyen

et al. 2022

Preprint

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BackgroundAs of December 30, 2021, Ontario long-term care (LTC) residents who received a third dose of COVID-19 vaccine ≥84 days previously were offered a fourth dose to prevent a surge in COVID-19-related morbidity and mortality due to the Omicron variant.MethodsWe used a test-negative design and linked databases to estimate the marginal effectiveness (4 versus 3 doses) and vaccine effectiveness (VE; 2, 3, or 4 doses versus no doses) of mRNA vaccines among Ontario LTC residents aged ≥60 years who were tested for SARS-CoV-2 between December 30, 2021 and March 2, 2022. Outcome measures included any Omicron infection, symptomatic infection, and severe outcomes (hospitalization or death).ResultsWe included 9,957 Omicron cases and 46,849 test-negative controls. The marginal effectiveness of a fourth dose ≥7 days after vaccination versus a third dose received ≥84 days prior was 40% (95% Confidence Interval[CI], 34-45%) against infection, 63% (95%CI, 51-71%) against symptomatic infection, and 54% (95%CI, 31-70%) against severe outcomes. VE (compared to an unvaccinated group) increased with each additional dose, and for a fourth dose was 65% (95%CI, 60-70%), 87% (95%CI, 81-91%), and 92% (95%CI, 87-95%), against infection, symptomatic infection, and severe outcomes, respectively.ConclusionsOur findings suggest that compared to a third dose received ≥84 days ago, a fourth dose recommendation for LTC residents improved protection against infection, symptomatic infection, and severe outcomes caused by Omicron. Compared to unvaccinated individuals, fourth doses provide strong protection against symptomatic infection and severe outcomes but the duration of protection remains unknown.

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“…When booster doses were offered, these could be either of the mRNA vaccines regardless of the vaccine product used for the primary series. Several vaccine effectiveness studies using registry data have been done in Norway, showing good protection against severe disease among the general population as well as specific population groups [7] , [11] , [14] , [15] . In line with other studies, the vaccine effectiveness differed between SARS-CoV variants, effectiveness estimates were higher against more severe outcomes and protection waned with time since last received dose.…”

Section: Introductionmentioning

confidence: 99%

Estimated vaccine effectiveness against SARS-CoV-2 Delta and Omicron infections among health care workers and the general adult population in Norway, August 2021 – January 2022

Langlete

Tesli

Veneti

et al. 2023

Vaccine

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High vaccine effectiveness against coronavirus disease 2019 (COVID-19) and severe disease among residents and staff of long-term care facilities in Norway, November 2020–June 2021

Cited by 6 publications

References 11 publications

Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study

Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study

Effectiveness of a Fourth Dose of COVID-19 Vaccine among Long-Term Care Residents in Ontario, Canada: Test-Negative Design Study

Estimated vaccine effectiveness against SARS-CoV-2 Delta and Omicron infections among health care workers and the general adult population in Norway, August 2021 – January 2022

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