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Costantino V, Trent M, MacIntyre CR. Modelling of optimal timing for influenza vaccination as a function of intraseasonal waning of immunity and vaccine coverage. Vaccine 2019; 37:6768-6775. [PMID: 31521411 DOI: 10.1016/j.vaccine.2019.08.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/14/2019] [Accepted: 08/27/2019] [Indexed: 02/08/2023]
Abstract
The influenza season in Australia usually peaks in August. Vaccination is recommended beginning in March-April. Recent studies suggest that vaccine effectiveness may wane over a given influenza season, leading to reduced effectiveness at the peak of the season. We aimed to quantify how changes in timing of influenza vaccination and declining vaccine coverage could change the percentages of prevented cases. Results from a systematic review were used to inform calculation of a waning function over time from vaccination. Age specific notification data and vaccine effectiveness and coverage estimates from 2007 to 2016 (2009 influenza pandemic year excluded) were used to model a new notification series where vaccine effectiveness is shifted in time to account for delayed vaccination by month from March to August. A sensitivity analysis was done on possible vaccine coverage changes and considering time gap between vaccine uptake and recommendation. Delaying vaccination from March to end of May prevents more cases over a season, but the variation in cases prevented by month of vaccination is not large. If delaying vaccination results in missed or forgotten vaccination and decrease coverage, delaying vaccination could have a net negative impact. Furthermore, considering a time gap between recommendation and uptake, earlier recommendation is more effective in preventing cases. The results are sensitive to assumptions of intra-seasonal waning of effectiveness. More research is required on intra-seasonal vaccine effectiveness waning and the effect of delayed vaccination on overall uptake to inform any potential changes to current vaccine scheduling recommendations.
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Affiliation(s)
- Valentina Costantino
- Biosecurity Program, Kirby Institute, Faculty of Medicine, The University of New South Wales, Sydney, Australia.
| | - Mallory Trent
- Biosecurity Program, Kirby Institute, Faculty of Medicine, The University of New South Wales, Sydney, Australia.
| | - C Raina MacIntyre
- Biosecurity Program, Kirby Institute, Faculty of Medicine, The University of New South Wales, Sydney, Australia; College of Public Service and Community Solutions, Arizona State University, Arizona, USA.
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Chamba Pardo FO, Schelkopf A, Allerson M, Morrison R, Culhane M, Perez A, Torremorell M. Breed-to-wean farm factors associated with influenza A virus infection in piglets at weaning. Prev Vet Med 2018; 161:33-40. [PMID: 30466656 DOI: 10.1016/j.prevetmed.2018.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 09/10/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022]
Abstract
Breed-to-wean pig farms play an important role in spreading influenza A virus (IAV) because suckling piglets maintain, diversify and transmit IAV at weaning to other farms. Understanding the nature and extent of which farm factors drive IAV infection in piglets is a prerequisite to reduce the burden of influenza in swine. We evaluated the association between IAV infection in piglets at weaning and farm factors including farm features, herd management practices and gilt- and piglet-specific management procedures performed at the farm. Voluntarily enrolled breed-to-wean farms (n = 83) agreed to share IAV diagnostic testing and farm data from July 2011 through March 2017 including data obtained via the administration of a survey. There were 23% IAV RT-PCR positive samples of the 12,814 samples submitted for IAV testing within 2989 diagnostic submissions with 30% positive submissions. Among all the factors evaluated (n = 24), and considering the season-adjusted multivariable analysis, only sow IAV vaccination and gilt IAV status at entry significantly reduced (p-value<0.05) IAV infections in piglets at weaning. Results from this study indicate that veterinarians and producers could manage these identified factors to reduce the burden of influenza in piglets prior to wean and perhaps, reduce the spread of IAV to other farms and people.
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Affiliation(s)
- Fabian Orlando Chamba Pardo
- Veterinary Population Medicine Department, University of Minnesota, 335 AS/VM, 1988 Fitch Ave., St. Paul, MN 55108, USA.
| | - Adam Schelkopf
- Health Department, Pipestone Veterinary Services, 1300 South Highway 75, PO Box 188, Pipestone, MN 56164, USA.
| | - Matthew Allerson
- Health and Research Department, Holden Farms Inc., 457 375th street, Dennison, MN 55018, USA.
| | - Robert Morrison
- Veterinary Population Medicine Department, University of Minnesota, 335 AS/VM, 1988 Fitch Ave., St. Paul, MN 55108, USA.
| | - Marie Culhane
- Veterinary Population Medicine Department, University of Minnesota, 335 AS/VM, 1988 Fitch Ave., St. Paul, MN 55108, USA.
| | - Andres Perez
- Veterinary Population Medicine Department, University of Minnesota, 335 AS/VM, 1988 Fitch Ave., St. Paul, MN 55108, USA.
| | - Montserrat Torremorell
- Veterinary Population Medicine Department, University of Minnesota, 335 AS/VM, 1988 Fitch Ave., St. Paul, MN 55108, USA.
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