Investigations into a trigger-based approach for initiating emergency vaccination to augment stamping out of foot-and-mouth disease in New Zealand: a simulation study

Sanson, R. L.; Yu, Zhidong; Rawdon, T G; Andel, Mary van

doi:10.1080/00480169.2021.1921069

Cited by 4 publications

(10 citation statements)

References 23 publications

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“…Ultimately, we estimated the need to depopulate 120 farms and vaccinate 25,000 animals within seven days to eliminate all simulated epidemics, which seems extremely unrealistic given the current state of Rio Grande do Sul staffing and available resources. Thus, we reach the same conclusion as the modeling work done in Austria, which found that the number of animal health officials for surveillance and control activities would need to be doubled to allow proper large-scale epidemic management (Boklund et al, 2017;Marschik et al, 2021;Sanson et al, 2021). Finally, our model provides guidance to Brazilian policy-makers, and our results are the first to provide rules of thumb based on the number of infected farms, to choose whether to deploy vaccination.…”

Section: Discussionsupporting

confidence: 71%

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

Cárdenas

Lopes

Machado

2022

Preprint

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Foot-and-mouth disease (FMD) infects multiple food-animal species, thus capable of disseminating among ungulate species with distinct transmission rates. Here present a multilevel compartmental stochastic model, taking into account births and deaths and explicit representation of species-specific transmission dynamics. The model considered two major modes of dissemination, between-farm animal and spatial transmission. Our model outcomes are the number of secondary infected animals and farms, spatial dissemination distances, and effectiveness of depopulation and vaccination along with surveillance and movement restrictions. We demonstrated that after 20 days of FMD dissemination, the median number of infected farms was 8 (IQR: 3-22), of which 7 (IQR: 3-22) were bovine, 3 (IQR: 1-6) swine farms, and 1 (IQR: 1-1) small ruminants. We demonstrate that animal movement dominated dissemination in the first days of epidemics, while at ten days the spatial transmission dominated bovine infections, whilst between-farm led to most swine infections. We have also shown the median distances between seeded and secondary infections was 5.77 km (IQR: 1-10.29 km), with some long-range dissemination at 695.40 km. We estimated that depopulating 12 and vaccinating 15,000 farms per day faded out 98.3% of the epidemics, however, was insufficient to contain large-scale epidemics (> 248 infected farms). The estimated effectiveness of a baseline control scenario eliminated 93.4% of the epidemics with a median of 9 (IQR: 3-23, max: 221) infected farms. Our results demonstrated that the depopulation alone against epidemics with more than 74 infected farms had limited success, stamping out less than 80% of simulations. The developed transmission model allows for cross-species transmission to be considered in FMD policy-making, and the software implementation facilitates the adaption of scientific-based support to FMD planning and response throughout other Brazilian states.

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Section: Discussionsupporting

confidence: 71%

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

Cárdenas

Lopes

Machado

2022

Preprint

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“…Modelling studies in New Zealand, 16 Denmark, 35 and Scotland 8 also focused on further targeting vaccine doses and varying response resources during a potential FMD outbreak. 16 found that the odds of a large outbreak were decreased by 22% by allowing dynamic outbreak statistics that are predictive of outbreak extent to influence the triggering of vaccination. This adaptive strategy administered a median of almost 37,000 doses of vaccine with a range up to almost 557,000 doses.…”

Section: Discussionmentioning

confidence: 99%

“…A fixed national supply of vaccine doses was allocated in two manners – proportionally to individual states and under a shared vaccine pool arrangement. As previous work had shown that the availability of response resources, particularly the ability to find and remove infected premises, is a key determinant of control programs' effectiveness, 13 , 15 , 16 we also ran simulations varying surveillance resources. Trade‐offs between outbreak extents' effects on economic impact and changes in updated estimates of government response costs were determined.…”

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confidence: 99%

FMD vaccine allocation and surveillance resourcing options for a potential Australian incursion

et al. 2022

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“…This was to allow the impacts of vaccination on personnel resource usage and response outcomes to be explored, should vaccination be adopted as a policy measure. Three variants of the vaccination programme were modelled: when an early decision indicator triggering that a large outbreak was developing, a random start between Days 11 and 35 of the response inclusive, and a fixed start on Day 21 of the response (see Sanson et al., 2021a, 2021b for more details). Day 11 was considered the earliest that a vaccination programme could realistically begin in a large scale in New Zealand.…”

Section: Methodsmentioning

confidence: 99%

Modelling the field personnel resources to control foot‐and‐mouth disease outbreaks in New Zealand

Sanson¹,

Rawdon

Andel

et al. 2022

Transbounding Emerging Dis

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The objective of the study was to simulate New Zealand’s foot‐and‐mouth disease (FMD) operational plan to determine personnel requirements for an FMD response and understand how the numbers of front‐line staff available could affect the size and duration of FMD outbreaks, when using stamping‐out (SO) measures with or without vaccination. The model utilized a national dataset of all known livestock farms. Each simulation randomly seeded infection into a single farm. Transmission mechanisms included direct and indirect contacts, local and airborne spread. Prior to each simulation, the numbers of personnel available for front‐line tasks (including contact tracing, surveillance of at‐risk farms, depopulation and vaccination) were set randomly. In a random subset of simulations, vaccination was allowed to be deployed as an adjunct to SO. The effects of personnel numbers on the size and duration of epidemics were explored using machine learning methods. In the second stage of the study, using a subset of iterations where numbers of personnel were unconstrained, the number of personnel used each day were quantified. When personnel resources were unconstrained, the 95th percentile and maximum number of infected places (IPs) were 78 and 462, respectively, and the 95th percentile and maximum duration were 69 and 217 days, respectively. However, severe constraints on personnel resources allowed some outbreaks to exceed the size of the UK 2001 FMD epidemic which had 2026 IPs. The number of veterinarians available had a major influence on the size and duration of outbreaks, whereas the availability of other personnel types did not. A shortage of veterinarians was associated with an increase in time to detect and depopulate IPs, allowing for continued transmission. Emergency vaccination placed a short‐term demand for additional staff at the start of the vaccination programme, but the overall number of person days used was similar to SO‐only strategies. This study determined the optimal numbers of front‐line personnel required to implement the current operational plans to support an FMD response in New Zealand. A shortage of veterinarians was identified as the most influential factor to impact disease control outcomes. Emergency vaccination led to earlier control of FMD outbreaks but at the cost of a short‐term spike in demand for personnel. In conclusion, a successful response needs to have access to sufficient personnel, particularly veterinarians, trained in response roles and available at short notice.

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Investigations into a trigger-based approach for initiating emergency vaccination to augment stamping out of foot-and-mouth disease in New Zealand: a simulation study

Cited by 4 publications

References 23 publications

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

Modeling foot-and-mouth disease dissemination in Brazil and evaluating the effectiveness of control measures

FMD vaccine allocation and surveillance resourcing options for a potential Australian incursion

Modelling the field personnel resources to control foot‐and‐mouth disease outbreaks in New Zealand

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