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Osakuade OW, Anyam NV. Major considerations in vaccinating children in Africa against COVID-19. Vaccine X 2022; 12:100199. [PMID: 35945971 PMCID: PMC9352650 DOI: 10.1016/j.jvacx.2022.100199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 05/05/2022] [Accepted: 07/29/2022] [Indexed: 11/17/2022] Open
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2
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Steyn N, Plank MJ, Binny RN, Hendy SC, Lustig A, Ridings K. A COVID-19 vaccination model for Aotearoa New Zealand. Sci Rep 2022; 12:2720. [PMID: 35177804 PMCID: PMC8854696 DOI: 10.1038/s41598-022-06707-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 02/01/2022] [Indexed: 12/16/2022] Open
Abstract
We develop a mathematical model to estimate the effect of New Zealand's vaccine rollout on the potential spread and health impacts of COVID-19. The main purpose of this study is to provide a basis for policy advice on border restrictions and control measures in response to outbreaks that may occur during the vaccination roll-out. The model can be used to estimate the theoretical population immunity threshold, which represents a point in the vaccine rollout at which border restrictions and other controls could be removed and only small, occasional outbreaks would take place. We find that, with a basic reproduction number of 6, approximately representing the Delta variant of SARS-CoV-2, and under baseline vaccine effectiveness assumptions, reaching the population immunity threshold would require close to 100% of the total population to be vaccinated. Since this coverage is not likely to be achievable in practice, relaxing controls completely would risk serious health impacts. However, the higher vaccine coverage is, the more collective protection the population has against adverse health outcomes from COVID-19, and the easier it will become to control outbreaks. There remains considerable uncertainty in model outputs, in part because of the potential for the evolution of new variants. If new variants arise that are more transmissible or vaccine resistant, an increase in vaccine coverage will be needed to provide the same level of protection.
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Affiliation(s)
- Nicholas Steyn
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand
- Department of Physics, University of Auckland, Auckland, New Zealand
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand
| | - Michael J Plank
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand.
- School of Mathematics and Statistics, University of Canterbury, Christchurch, New Zealand.
| | - Rachelle N Binny
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand
- Manaaki Whenua, Lincoln, New Zealand
| | - Shaun C Hendy
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand
- Department of Physics, University of Auckland, Auckland, New Zealand
| | - Audrey Lustig
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand
- Manaaki Whenua, Lincoln, New Zealand
| | - Kannan Ridings
- Te Pūnaha Matatini: the Centre for Complex Systems and Networks, Auckland, New Zealand
- Department of Physics, University of Auckland, Auckland, New Zealand
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3
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Gros C, Czypionka T, Gros D. When to end a lock down? How fast must vaccination campaigns proceed in order to keep health costs in check? ROYAL SOCIETY OPEN SCIENCE 2022; 9:211055. [PMID: 35116144 PMCID: PMC8790384 DOI: 10.1098/rsos.211055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 11/12/2021] [Indexed: 06/02/2023]
Abstract
We propose a simple rule of thumb for countries which have embarked on a vaccination campaign while still facing the need to keep non-pharmaceutical interventions (NPI) in place because of the ongoing spread of SARS-CoV-2. If the aim is to keep the death rate from increasing, NPIs can be loosened when it is possible to vaccinate more than twice the growth rate of new cases. If the aim is to keep the pressure on hospitals under control, the vaccination rate has to be about four times higher. These simple rules can be derived from the observation that the risk of death or a severe course requiring hospitalization from a COVID-19 infection increases exponentially with age and that the sizes of age cohorts decrease linearly at the top of the population pyramid. Protecting the over 60-year-olds, which constitute approximately one-quarter of the population in Europe (and most OECD countries), reduces the potential loss of life by 95 percent.
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Affiliation(s)
- Claudius Gros
- Institute for Theoretical Physics, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Thomas Czypionka
- Institute for Advanced Studies, Vienna, Austria
- Department of Health Policy, London School of Economics and Political Science, London, England
| | - Daniel Gros
- CEPS (Centre for European Policy Studies), Brussels, Belgium
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Imai N, Hogan AB, Williams L, Cori A, Mangal TD, Winskill P, Whittles LK, Watson OJ, Knock ES, Baguelin M, Perez-Guzman PN, Gaythorpe KA, Sonabend R, Ghani AC, Ferguson NM. Interpreting estimates of coronavirus disease 2019 (COVID-19) vaccine efficacy and effectiveness to inform simulation studies of vaccine impact: a systematic review. Wellcome Open Res 2021. [DOI: 10.12688/wellcomeopenres.16992.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Background: The multiple efficacious vaccines authorised for emergency use worldwide represent the first preventative intervention against coronavirus disease 2019 (COVID-19) that does not rely on social distancing measures. The speed at which data are emerging and the heterogeneities in study design, target populations, and implementation make it challenging to interpret and assess the likely impact of vaccine campaigns on local epidemics. We reviewed available vaccine efficacy and effectiveness studies to generate working estimates that can be used to parameterise simulation studies of vaccine impact. Methods: We searched MEDLINE, the World Health Organization’s Institutional Repository for Information Sharing, medRxiv, and vaccine manufacturer websites for studies that evaluated the emerging data on COVID-19 vaccine efficacy and effectiveness. Studies providing an estimate of the efficacy or effectiveness of a COVID-19 vaccine using disaggregated data against SARS-CoV-2 infection, symptomatic disease, severe disease, death, or transmission were included. We extracted information on study population, variants of concern (VOC), vaccine platform, dose schedule, study endpoints, and measures of impact. We applied an evidence synthesis approach to capture a range of plausible and consistent parameters for vaccine efficacy and effectiveness that can be used to inform and explore a variety of vaccination strategies as the COVID-19 pandemic evolves. Results: Of the 602 articles and reports identified, 53 were included in the analysis. The availability of vaccine efficacy and effectiveness estimates varied by vaccine and were limited for VOCs. Estimates for non-primary endpoints such as effectiveness against infection and onward transmission were sparse. Synthesised estimates were relatively consistent for the same vaccine platform for wild-type, but was more variable for VOCs. Conclusions: Assessment of efficacy and effectiveness of COVID-19 vaccines is complex. Simulation studies must acknowledge and capture the uncertainty in vaccine effectiveness to robustly explore and inform vaccination policies and policy around the lifting of non-pharmaceutical interventions.
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Patel MK, Bergeri I, Bresee JS, Cowling BJ, Crowcroft NS, Fahmy K, Hirve S, Kang G, Katz MA, Lanata CF, L'Azou Jackson M, Joshi S, Lipsitch M, Mwenda JM, Nogareda F, Orenstein WA, Ortiz JR, Pebody R, Schrag SJ, Smith PG, Srikantiah P, Subissi L, Valenciano M, Vaughn DW, Verani JR, Wilder-Smith A, Feikin DR. Evaluation of post-introduction COVID-19 vaccine effectiveness: Summary of interim guidance of the World Health Organization. Vaccine 2021; 39:4013-4024. [PMID: 34119350 PMCID: PMC8166525 DOI: 10.1016/j.vaccine.2021.05.099] [Citation(s) in RCA: 87] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/27/2021] [Indexed: 01/07/2023]
Abstract
Phase 3 randomized-controlled trials have provided promising results of COVID-19 vaccine efficacy, ranging from 50 to 95% against symptomatic disease as the primary endpoints, resulting in emergency use authorization/listing for several vaccines. However, given the short duration of follow-up during the clinical trials, strict eligibility criteria, emerging variants of concern, and the changing epidemiology of the pandemic, many questions still remain unanswered regarding vaccine performance. Post-introduction vaccine effectiveness evaluations can help us to understand the vaccine's effect on reducing infection and disease when used in real-world conditions. They can also address important questions that were either not studied or were incompletely studied in the trials and that will inform evolving vaccine policy, including assessment of the duration of effectiveness; effectiveness in key subpopulations, such as the very old or immunocompromised; against severe disease and death due to COVID-19; against emerging SARS-CoV-2 variants of concern; and with different vaccination schedules, such as number of doses and varying dosing intervals. WHO convened an expert panel to develop interim best practice guidance for COVID-19 vaccine effectiveness evaluations. We present a summary of the interim guidance, including discussion of different study designs, priority outcomes to evaluate, potential biases, existing surveillance platforms that can be used, and recommendations for reporting results.
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Affiliation(s)
- Minal K Patel
- World Health Organization, 20 Avenue Appia, Geneva 1211, Switzerland.
| | - Isabel Bergeri
- World Health Organization, 20 Avenue Appia, Geneva 1211, Switzerland
| | - Joseph S Bresee
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, USA
| | - Benjamin J Cowling
- School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China
| | | | - Kamal Fahmy
- World Health Organization Regional Office for the Eastern Mediterranean, Monazamet El Seha El Alamia Str, Extension of Abdel Razak El Sanhouri Street, P.O. Box 7608, Nasr City, Cairo 11371, Egypt
| | | | - Gagandeep Kang
- Christian Medical College, Ida Scudder Road, Vellore, Tamil Nadu 632004, India
| | - Mark A Katz
- World Health Organization Regional Office of Europe, UN City, Marmorvej 51, Copenhagen DK-2100, Denmark
| | - Claudio F Lanata
- Instituto de Investigación Nutricional, Av. la Molina 1885, La Molina 15024, Peru
| | - Maïna L'Azou Jackson
- The Coalition for Epidemic Preparedness Innovations (CEPI), Gibbs building, 215 Euston Rd, Bloomsbury, London NW1 2BE, United Kingdom
| | - Sudhir Joshi
- World Health Organization Regional Office for South-East Asia, World Health House, Indraprastha Estate, Mahatma Gandhi Marg, New Delhi 110 002, India
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Jason M Mwenda
- World Health Organization Regional Office for Africa, Cité du Djoué, P.O. Box 06, Brazzaville, Republic of Congo
| | - Francisco Nogareda
- Consultant to the Pan American Health Organization, 525 23rd Street NW, Washington, DC 20037, USA
| | | | - Justin R Ortiz
- Center for Vaccine Development & Global Health, University of Maryland School of Medicine, 685 W. Baltimore St., Room #480, Baltimore, MD 21201, USA
| | - Richard Pebody
- World Health Organization Regional Office of Europe, UN City, Marmorvej 51, Copenhagen DK-2100, Denmark
| | - Stephanie J Schrag
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, USA
| | - Peter G Smith
- MRC International Epidemiology & Statistics Group, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | | | - Lorenzo Subissi
- World Health Organization, 20 Avenue Appia, Geneva 1211, Switzerland
| | | | - David W Vaughn
- Bill & Melinda Gates Foundation, 500 5th Ave N., Seattle, WA 98109, USA
| | - Jennifer R Verani
- U.S. Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, USA
| | | | - Daniel R Feikin
- World Health Organization, 20 Avenue Appia, Geneva 1211, Switzerland
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Viana J, van Dorp CH, Nunes A, Gomes MC, van Boven M, Kretzschmar ME, Veldhoen M, Rozhnova G. Controlling the pandemic during the SARS-CoV-2 vaccination rollout. Nat Commun 2021; 12:3674. [PMID: 34135335 PMCID: PMC8209021 DOI: 10.1038/s41467-021-23938-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 05/24/2021] [Indexed: 02/07/2023] Open
Abstract
There is a consensus that mass vaccination against SARS-CoV-2 will ultimately end the COVID-19 pandemic. However, it is not clear when and which control measures can be relaxed during the rollout of vaccination programmes. We investigate relaxation scenarios using an age-structured transmission model that has been fitted to age-specific seroprevalence data, hospital admissions, and projected vaccination coverage for Portugal. Our analyses suggest that the pressing need to restart socioeconomic activities could lead to new pandemic waves, and that substantial control efforts prove necessary throughout 2021. Using knowledge on control measures introduced in 2020, we anticipate that relaxing measures completely or to the extent as in autumn 2020 could launch a wave starting in April 2021. Additional waves could be prevented altogether if measures are relaxed as in summer 2020 or in a step-wise manner throughout 2021. We discuss at which point the control of COVID-19 would be achieved for each scenario.
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Affiliation(s)
- João Viana
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Christiaan H van Dorp
- Theoretical Biology and Biophysics (T-6), Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Ana Nunes
- Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Manuel C Gomes
- Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Michiel van Boven
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Mirjam E Kretzschmar
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Marc Veldhoen
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Ganna Rozhnova
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
- BioISI-Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.
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Zimmerman RK. Helping patients with ethical concerns about COVID-19 vaccines in light of fetal cell lines used in some COVID-19 vaccines. Vaccine 2021; 39:4242-4244. [PMID: 34172329 PMCID: PMC8205255 DOI: 10.1016/j.vaccine.2021.06.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 01/12/2023]
Abstract
Many persons with religious convictions report hesitancy about COVID-19 vaccines, in part due to ethical concerns that fetal cell lines are used in the development of certain vaccines. The issue of abortion is contentious and, given the potential impact on COVID-19 vaccination, it is important for clinicians to be aware of this issue, whatever their personal beliefs. I provide four responses that clinicians may offer their patients: 1) Ethical analyses of moral complicity and COVID vaccines. 2) Altruism and protecting others from a virus that is often transmitted while asymptomatic or pre-symptomatic. 3) Religious texts and many religious leaders support prevention and, therefore, vaccination. 4) Administration of vaccines not developed in fetal cell lines. Although I wish for all my patients to be vaccinated, I respect their autonomy to make the choice to be or not to be vaccinated and understand that many have a deep regard for fetal life.
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Affiliation(s)
- Richard K Zimmerman
- University of Pittsburgh, School of Medicine, Department of Family Medicine, USA; Graduate School of Public Health, Department of Behavioral and Community Health Sciences, Pittsburgh, PA, USA.
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8
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Sah P, Vilches TN, Moghadas SM, Fitzpatrick MC, Singer BH, Hotez PJ, Galvani AP. Accelerated vaccine rollout is imperative to mitigate highly transmissible COVID-19 variants. EClinicalMedicine 2021; 35:100865. [PMID: 33937735 PMCID: PMC8072134 DOI: 10.1016/j.eclinm.2021.100865] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/06/2021] [Accepted: 04/07/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND More contagious variants of SARS-CoV-2 have emerged around the world, sparking concerns about impending surge in cases and severe outcomes. Despite the development of effective vaccines, rollout has been slow. We evaluated the impact of accelerated vaccine distribution on curbing the disease burden of novel SARS-CoV-2 variants. METHODS We used an agent-based model of SARS-CoV-2 transmission and vaccination to simulate the spread of novel variants with S-Gene Target Failure (SGTF) in addition to the original strain. We incorporated age-specific risk and contact patterns and implemented a two-dose vaccination campaign in accord with CDC-recommended prioritization. As a base case, we projected hospitalizations and deaths at a daily vaccination rate of 1 million doses in the United States (US) and compared with accelerated campaigns in which daily doses were expanded to 1.5, 2, 2.5, or 3 million. FINDINGS We found that at a vaccination rate of 1 million doses per day, an emergent SGTF variant that is 20-70% more transmissible than the original variant would become dominant within 2 to 9 weeks, accounting for as much as 99% of cases at the outbreak peak. Our results show that accelerating vaccine delivery would substantially reduce severe health outcomes. For a SGTF with 30% higher transmissibility, increasing vaccine doses from 1 to 3 million per day would avert 152,048 (95% CrI: 134,772-168,696) hospitalizations and 48,448 (95% CrI: 42,042-54,285) deaths over 300 days. Accelerated vaccination would also prevent additional COVID-19 waves that would otherwise be fuelled by waning adherence to non-pharmaceutical interventions (NPIs). INTERPRETATION We found that the current pace of vaccine rollout is insufficient to prevent the exacerbation of the pandemic that will be attributable to the novel, more contagious SARS-CoV-2 variants. Accelerating the vaccination rate should be a public health priority for averting the expected surge in COVID-19 hospitalizations and deaths that would be associated with widespread dissemination of the SGTF variants. Our results underscore the need to bolster the production and distribution of COVID-19 vaccines, to rapidly expand vaccination priority groups and distribution sites.
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Affiliation(s)
- Pratha Sah
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, CT, USA
| | - Thomas N. Vilches
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3 Canada
| | - Seyed M. Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario M3J 1P3 Canada
| | - Meagan C. Fitzpatrick
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, CT, USA
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W Baltimore St, Baltimore, MD 21201, USA
| | - Burton H. Singer
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA
| | - Peter J. Hotez
- National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Alison P. Galvani
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, CT, USA
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9
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Farthing TS, Lanzas C. When can we stop wearing masks? Agent-based modeling to identify when vaccine coverage makes nonpharmaceutical interventions for reducing SARS-CoV-2 infections redundant in indoor gatherings. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2021:2021.04.19.21255737. [PMID: 33948613 PMCID: PMC8095232 DOI: 10.1101/2021.04.19.21255737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
As vaccination efforts to combat the COVID-19 pandemic are ramping up worldwide, there are rising concerns that individuals will begin to eschew nonpharmaceutical interventions for preventing SARS-CoV-2 transmission and attempt to return to pre-pandemic normalcy before vaccine coverage levels effectively mitigate transmission risk. In the U.S.A., some governing bodies have already weakened or repealed guidelines for nonpharmaceutical intervention use, despite a recent spike in national COVID-19 cases and majority population of unvaccinated individuals. Recent modeling suggests that repealing nonpharmaceutical intervention guidelines too early into vaccine rollouts will lead to localized increases in COVID-19 cases, but the magnitude of nonpharmaceutical intervention effects on individual-level SARS-CoV-2 infection risk in fully- and partially-vaccinated populations is unclear. We use a previously-published agent-based model to simulate SARS-CoV-2 transmission in indoor gatherings of varying durations, population densities, and vaccination coverage levels. By simulating nonpharmaceutical interventions in some gatherings but not others, we were able to quantify the difference in SARS-CoV-2 infection risk when nonpharmaceutical interventions were used, relative to scenarios with no nonpharmaceutical interventions. We found that nonpharmaceutical interventions will often reduce secondary attack rates, especially during brief interactions, and therefore there is no definitive vaccination coverage level that makes nonpharmaceutical interventions completely redundant. However, the reduction effect on absolute SARS-CoV-2 infection risk conferred by nonpharmaceutical interventions is likely proportional to COVID-19 prevalence. Therefore, if COVID-19 prevalence decreases in the future, nonpharmaceutical interventions will likely still confer protective effects but potential benefits may be small enough to remain within "effectively negligible" risk thresholds.
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Affiliation(s)
| | - Cristina Lanzas
- North Carolina State University, Raleigh, North Carolina, USA
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10
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Vilches TN, Nourbakhsh S, Zhang K, Juden-Kelly L, Cipriano LE, Langley JM, Sah P, Galvani AP, Moghadas SM. Multifaceted strategies for the control of COVID-19 outbreaks in long-term care facilities in Ontario, Canada. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2021:2020.12.04.20244194. [PMID: 33330884 PMCID: PMC7743093 DOI: 10.1101/2020.12.04.20244194] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The novel coronavirus disease 2019 (COVID-19) has caused severe outbreaks in Canadian long-term care facilities (LTCFs). In Canada, over 80% of COVID-19 deaths during the first pandemic wave occurred in LTCFs. We sought to evaluate the effect of mitigation measures in LTCFs including frequent testing of staff, and vaccination of staff and residents. We developed an agent-based transmission model and parameterized it with disease-specific estimates, temporal sensitivity of nasopharyngeal and saliva testing, results of vaccine efficacy trials, and data from initial COVID-19 outbreaks in LTCFs in Ontario, Canada. Characteristics of staff and residents, including contact patterns, were integrated into the model with age-dependent risk of hospitalization and death. Estimates of infection and outcomes were obtained and 95% credible intervals were generated using a bias-corrected and accelerated bootstrap method. Weekly routine testing of staff with 2-day turnaround time reduced infections among residents by at least 25.9% (95% CrI: 23.3% - 28.3%), compared to baseline measures of mask-wearing, symptom screening, and staff cohorting alone. A similar reduction of hospitalizations and deaths was achieved in residents. Vaccination averted 2-4 times more infections in both staff and residents as compared to routine testing, and markedly reduced hospitalizations and deaths among residents by 95.9% (95% CrI: 95.4% - 96.3%) and 95.8% (95% CrI: 95.5% - 96.1%), respectively, over 200 days from the start of vaccination. Vaccination could have a substantial impact on mitigating disease burden among residents, but may not eliminate the need for other measures before population-level control of COVID-19 is achieved.
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Affiliation(s)
- Thomas N. Vilches
- Institute of Mathematics, Statistics and Scientific Computing, University of Campinas, Campinas SP, Brazil
| | - Shokoofeh Nourbakhsh
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Kevin Zhang
- Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8 Canada
| | - Lyndon Juden-Kelly
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Lauren E. Cipriano
- Ivey Business School and Department of Epidemiology and Biostatistics, Schulich School of Medicine & Dentistry, Western University, London, Ontario N6G 0N1 Canada
| | - Joanne M. Langley
- Canadian Center for Vaccinology, Dalhousie University, IWK Health Centre and Nova Scotia Health Authority, Halifax, Nova Scotia, B3K 6R8 Canada
| | - Pratha Sah
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA
| | - Alison P. Galvani
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA
| | - Seyed M. Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada
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11
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Moghadas SM, Vilches TN, Zhang K, Nourbakhsh S, Sah P, Fitzpatrick MC, Galvani AP. Evaluation of COVID-19 vaccination strategies with a delayed second dose. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2021:2021.01.27.21250619. [PMID: 33532805 PMCID: PMC7852256 DOI: 10.1101/2021.01.27.21250619] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Two of the COVID-19 vaccines currently approved in the United States require two doses, administered three to four weeks apart. Constraints in vaccine supply and distribution capacity, together with a deadly wave of COVID-19 from November 2020 to January 2021 and the emergence of highly contagious SARS-CoV-2 variants, sparked a policy debate on whether to vaccinate more individuals with the first dose of available vaccines and delay the second dose, or to continue with the recommended two-dose series as tested in clinical trials. We developed an agent-based model of COVID-19 transmission to compare the impact of these two vaccination strategies, while varying the temporal waning of vaccine efficacy following the first dose and the level of pre-existing immunity in the population. Our results show that for Moderna vaccines, a delay of at least 9 weeks could maximize vaccination program effectiveness and avert at least an additional 17.3 (95% CrI: 7.8 - 29.7) infections, 0.71 (95% CrI: 0.52 - 0.97) hospitalizations, and 0.34 (95% CrI: 0.25 - 0.44) deaths per 10,000 population compared to the recommended 4-week interval between the two doses. Pfizer-BioNTech vaccines also averted an additional 0.61 (95% CrI: 0.37 - 0.89) hospitalizations and 0.31 (95% CrI: 0.23 - 0.45) deaths per 10,000 population in a 9-week delayed second dose strategy compared to the 3-week recommended schedule between doses. However, there was no clear advantage of delaying the second dose with Pfizer-BioNTech vaccines in reducing infections, unless the efficacy of the first dose did not wane over time. Our findings underscore the importance of quantifying the characteristics and durability of vaccine-induced protection after the first dose in order to determine the optimal time interval between the two doses.
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Affiliation(s)
- Seyed M. Moghadas
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Thomas N. Vilches
- Institute of Mathematics, Statistics and Scientific Computing, University of Campinas, Campinas SP, Brazil
| | - Kevin Zhang
- Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8 Canada
| | - Shokoofeh Nourbakhsh
- Agent-Based Modelling Laboratory, York University, Toronto, Ontario, M3J 1P3 Canada
| | - Pratha Sah
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA
| | - Meagan C. Fitzpatrick
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W Baltimore St, Baltimore, MD 21201 USA
| | - Alison P. Galvani
- Center for Infectious Disease Modeling and Analysis (CIDMA), Yale School of Public Health, New Haven, Connecticut, USA
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Projecting the impact of a two-dose COVID-19 vaccination campaign in Ontario, Canada. Vaccine 2021; 39:2360-2365. [PMID: 33812742 PMCID: PMC7980181 DOI: 10.1016/j.vaccine.2021.03.058] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 12/15/2022]
Abstract
Background A number of highly effective COVID-19 vaccines have been developed and approved for mass vaccination. We evaluated the impact of vaccination on COVID-19 outbreak and disease outcomes in Ontario, Canada. Methods We used an agent-based transmission model and parameterized it with COVID-19 characteristics, demographics of Ontario, and age-specific clinical outcomes. We implemented a two-dose vaccination program according to tested schedules in clinical trials for Pfizer-BioNTech and Moderna vaccines, prioritizing healthcare workers, individuals with comorbidities, and those aged 65 and older. Daily vaccination rate was parameterized based on vaccine administration data. Using estimates of vaccine efficacy, we projected the impact of vaccination on the overall attack rate, hospitalizations, and deaths. We further investigated the effect of increased daily contacts at different stages during vaccination campaigns on outbreak control. Results Maintaining non-pharmaceutical interventions (NPIs) with an average of 74% reduction in daily contacts, vaccination with Pfizer-BioNTech and Moderna vaccines was projected to reduce hospitalizations by 27.3% (95% CrI: 22.3% − 32.4%) and 27.0% (95% CrI: 21.9% − 32.6%), respectively, over a one-year time horizon. The largest benefits of vaccination were observed in preventing deaths with reductions of 31.5% (95% CrI: 22.5% − 39.7%) and 31.9% (95% CrI: 22.0% − 41.4%) for Pfizer-BioNTech and Moderna vaccines, respectively, compared to no vaccination. We found that an increase of only 10% in daily contacts at the end of lockdown, when vaccination coverage with only one dose was 6%, would trigger a surge in the outbreak. Early relaxation of population-wide measures could lead to a substantial increase in the number of infections, potentially reaching levels observed during the peak of the second wave in Ontario. Conclusions Vaccination can substantially mitigate ongoing COVID-19 outbreaks. Sustaining population-wide NPIs, to allow for a sufficient increase in population-level immunity through vaccination, is essential to prevent future outbreaks.
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