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Vaccine effectiveness of the first dose of ChAdOx1 nCoV-19 and BNT162b2 against SARS-CoV-2 infection in residents of long-term care facilities in England (VIVALDI): a prospective cohort study.
Lancet Infect Dis. 2021 11; 21(11):1529-1538.LI

Abstract

BACKGROUND

The effectiveness of SARS-CoV-2 vaccines in older adults living in long-term care facilities is uncertain. We investigated the protective effect of the first dose of the Oxford-AstraZeneca non-replicating viral-vectored vaccine (ChAdOx1 nCoV-19; AZD1222) and the Pfizer-BioNTech mRNA-based vaccine (BNT162b2) in residents of long-term care facilities in terms of PCR-confirmed SARS-CoV-2 infection over time since vaccination.

METHODS

The VIVALDI study is a prospective cohort study that commenced recruitment on June 11, 2020, to investigate SARS-CoV-2 transmission, infection outcomes, and immunity in residents and staff in long-term care facilities in England that provide residential or nursing care for adults aged 65 years and older. In this cohort study, we included long-term care facility residents undergoing routine asymptomatic SARS-CoV-2 testing between Dec 8, 2020 (the date the vaccine was first deployed in a long-term care facility), and March 15, 2021, using national testing data linked within the COVID-19 Datastore. Using Cox proportional hazards regression, we estimated the relative hazard of PCR-positive infection at 0-6 days, 7-13 days, 14-20 days, 21-27 days, 28-34 days, 35-48 days, and 49 days and beyond after vaccination, comparing unvaccinated and vaccinated person-time from the same cohort of residents, adjusting for age, sex, previous infection, local SARS-CoV-2 incidence, long-term care facility bed capacity, and clustering by long-term care facility. We also compared mean PCR cycle threshold (Ct) values for positive swabs obtained before and after vaccination. The study is registered with ISRCTN, number 14447421.

FINDINGS

10 412 care home residents aged 65 years and older from 310 LTCFs were included in this analysis. The median participant age was 86 years (IQR 80-91), 7247 (69·6%) of 10 412 residents were female, and 1155 residents (11·1%) had evidence of previous SARS-CoV-2 infection. 9160 (88·0%) residents received at least one vaccine dose, of whom 6138 (67·0%) received ChAdOx1 and 3022 (33·0%) received BNT162b2. Between Dec 8, 2020, and March 15, 2021, there were 36 352 PCR results in 670 628 person-days, and 1335 PCR-positive infections (713 in unvaccinated residents and 612 in vaccinated residents) were included. Adjusted hazard ratios (HRs) for PCR-positive infection relative to unvaccinated residents declined from 28 days after the first vaccine dose to 0·44 (95% CI 0·24-0·81) at 28-34 days and 0·38 (0·19-0·77) at 35-48 days. Similar effect sizes were seen for ChAdOx1 (adjusted HR 0·32, 95% CI 0·15-0·66) and BNT162b2 (0·35, 0·17-0·71) vaccines at 35-48 days. Mean PCR Ct values were higher for infections that occurred at least 28 days after vaccination than for those occurring before vaccination (31·3 [SD 8·7] in 107 PCR-positive tests vs 26·6 [6·6] in 552 PCR-positive tests; p<0·0001).

INTERPRETATION

Single-dose vaccination with BNT162b2 and ChAdOx1 vaccines provides substantial protection against infection in older adults from 4-7 weeks after vaccination and might reduce SARS-CoV-2 transmission. However, the risk of infection is not eliminated, highlighting the ongoing need for non-pharmaceutical interventions to prevent transmission in long-term care facilities.

FUNDING

UK Government Department of Health and Social Care.

Authors+Show Affiliations

UCL Institute of Health Informatics, UCL, London, UK; Public Health England, London, UK.UCL Institute of Health Informatics, UCL, London, UK.UCL Institute for Global Health, UCL, London, UK.UCL Institute of Health Informatics, UCL, London, UK.UCL Institute of Health Informatics, UCL, London, UK.Public Health England, London, UK.UCL Institute of Health Informatics, UCL, London, UK.Department of Health and Social Care, London, UK.Palantir Technologies UK, London, UK.Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.Public Health England, London, UK.Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK.UCL Institute of Epidemiology & Healthcare, UCL, London, UK; Health Data Research UK, London, UK.UCL Institute for Global Health, UCL, London, UK.UCL Institute of Health Informatics, UCL, London, UK. Electronic address: l.shallcross@ucl.ac.uk.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

34174193

Citation

Shrotri, Madhumita, et al. "Vaccine Effectiveness of the First Dose of ChAdOx1 nCoV-19 and BNT162b2 Against SARS-CoV-2 Infection in Residents of Long-term Care Facilities in England (VIVALDI): a Prospective Cohort Study." The Lancet. Infectious Diseases, vol. 21, no. 11, 2021, pp. 1529-1538.
Shrotri M, Krutikov M, Palmer T, et al. Vaccine effectiveness of the first dose of ChAdOx1 nCoV-19 and BNT162b2 against SARS-CoV-2 infection in residents of long-term care facilities in England (VIVALDI): a prospective cohort study. Lancet Infect Dis. 2021;21(11):1529-1538.
Shrotri, M., Krutikov, M., Palmer, T., Giddings, R., Azmi, B., Subbarao, S., Fuller, C., Irwin-Singer, A., Davies, D., Tut, G., Lopez Bernal, J., Moss, P., Hayward, A., Copas, A., & Shallcross, L. (2021). Vaccine effectiveness of the first dose of ChAdOx1 nCoV-19 and BNT162b2 against SARS-CoV-2 infection in residents of long-term care facilities in England (VIVALDI): a prospective cohort study. The Lancet. Infectious Diseases, 21(11), 1529-1538. https://doi.org/10.1016/S1473-3099(21)00289-9
Shrotri M, et al. Vaccine Effectiveness of the First Dose of ChAdOx1 nCoV-19 and BNT162b2 Against SARS-CoV-2 Infection in Residents of Long-term Care Facilities in England (VIVALDI): a Prospective Cohort Study. Lancet Infect Dis. 2021;21(11):1529-1538. PubMed PMID: 34174193.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Vaccine effectiveness of the first dose of ChAdOx1 nCoV-19 and BNT162b2 against SARS-CoV-2 infection in residents of long-term care facilities in England (VIVALDI): a prospective cohort study. AU - Shrotri,Madhumita, AU - Krutikov,Maria, AU - Palmer,Tom, AU - Giddings,Rebecca, AU - Azmi,Borscha, AU - Subbarao,Sathyavani, AU - Fuller,Christopher, AU - Irwin-Singer,Aidan, AU - Davies,Daniel, AU - Tut,Gokhan, AU - Lopez Bernal,Jamie, AU - Moss,Paul, AU - Hayward,Andrew, AU - Copas,Andrew, AU - Shallcross,Laura, Y1 - 2021/06/23/ PY - 2021/03/26/received PY - 2021/05/04/revised PY - 2021/05/11/accepted PY - 2021/6/27/pubmed PY - 2021/11/10/medline PY - 2021/6/26/entrez SP - 1529 EP - 1538 JF - The Lancet. Infectious diseases JO - Lancet Infect Dis VL - 21 IS - 11 N2 - BACKGROUND: The effectiveness of SARS-CoV-2 vaccines in older adults living in long-term care facilities is uncertain. We investigated the protective effect of the first dose of the Oxford-AstraZeneca non-replicating viral-vectored vaccine (ChAdOx1 nCoV-19; AZD1222) and the Pfizer-BioNTech mRNA-based vaccine (BNT162b2) in residents of long-term care facilities in terms of PCR-confirmed SARS-CoV-2 infection over time since vaccination. METHODS: The VIVALDI study is a prospective cohort study that commenced recruitment on June 11, 2020, to investigate SARS-CoV-2 transmission, infection outcomes, and immunity in residents and staff in long-term care facilities in England that provide residential or nursing care for adults aged 65 years and older. In this cohort study, we included long-term care facility residents undergoing routine asymptomatic SARS-CoV-2 testing between Dec 8, 2020 (the date the vaccine was first deployed in a long-term care facility), and March 15, 2021, using national testing data linked within the COVID-19 Datastore. Using Cox proportional hazards regression, we estimated the relative hazard of PCR-positive infection at 0-6 days, 7-13 days, 14-20 days, 21-27 days, 28-34 days, 35-48 days, and 49 days and beyond after vaccination, comparing unvaccinated and vaccinated person-time from the same cohort of residents, adjusting for age, sex, previous infection, local SARS-CoV-2 incidence, long-term care facility bed capacity, and clustering by long-term care facility. We also compared mean PCR cycle threshold (Ct) values for positive swabs obtained before and after vaccination. The study is registered with ISRCTN, number 14447421. FINDINGS: 10 412 care home residents aged 65 years and older from 310 LTCFs were included in this analysis. The median participant age was 86 years (IQR 80-91), 7247 (69·6%) of 10 412 residents were female, and 1155 residents (11·1%) had evidence of previous SARS-CoV-2 infection. 9160 (88·0%) residents received at least one vaccine dose, of whom 6138 (67·0%) received ChAdOx1 and 3022 (33·0%) received BNT162b2. Between Dec 8, 2020, and March 15, 2021, there were 36 352 PCR results in 670 628 person-days, and 1335 PCR-positive infections (713 in unvaccinated residents and 612 in vaccinated residents) were included. Adjusted hazard ratios (HRs) for PCR-positive infection relative to unvaccinated residents declined from 28 days after the first vaccine dose to 0·44 (95% CI 0·24-0·81) at 28-34 days and 0·38 (0·19-0·77) at 35-48 days. Similar effect sizes were seen for ChAdOx1 (adjusted HR 0·32, 95% CI 0·15-0·66) and BNT162b2 (0·35, 0·17-0·71) vaccines at 35-48 days. Mean PCR Ct values were higher for infections that occurred at least 28 days after vaccination than for those occurring before vaccination (31·3 [SD 8·7] in 107 PCR-positive tests vs 26·6 [6·6] in 552 PCR-positive tests; p<0·0001). INTERPRETATION: Single-dose vaccination with BNT162b2 and ChAdOx1 vaccines provides substantial protection against infection in older adults from 4-7 weeks after vaccination and might reduce SARS-CoV-2 transmission. However, the risk of infection is not eliminated, highlighting the ongoing need for non-pharmaceutical interventions to prevent transmission in long-term care facilities. FUNDING: UK Government Department of Health and Social Care. SN - 1474-4457 UR - https://www.unboundmedicine.com/medline/citation/34174193/Vaccine_effectiveness_of_the_first_dose_of_ChAdOx1_nCoV_19_and_BNT162b2_against_SARS_CoV_2_infection_in_residents_of_long_term_care_facilities_in_England__VIVALDI_:_a_prospective_cohort_study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1473-3099(21)00289-9 DB - PRIME DP - Unbound Medicine ER -