Pertussis in England and Wales: an investigation of transmission dynamics and control by mass vaccination

1989 ◽  
Vol 236 (1284) ◽  
pp. 213-252 ◽  
Keyword(s):  
Mathematical Models ◽  
Vaccine Efficacy ◽  
Case Reports ◽  
Mass Vaccination ◽  
Vaccine Uptake ◽  
Transmission Dynamics ◽  
England And Wales ◽  
Epidemic Period ◽  
The Impact ◽  
Induced Immunity

The epidemiology of pertussis and its prospects for control by mass vaccination in England and Wales are investigated by analyses of longitudinal records on incidence and vaccine uptake, and horizontal data on age-stratified case reports. Mathematical models of the transmission dynamics of the infection that incorporate loss of natural and vaccine-induced immunity plus variable vaccine efficacy are developed, and their predictions compared with observed trends. Analyses of case reports reveal that the individual force of infection is age dependent, with peak transmission in the 5- to 10-year-old age class. A model incorporating this age dependency, along with partial vaccine efficacy and loss of vaccine-induced immunity, generates predicted patterns that best mirror observed trends since mass vaccination was inaugurated in 1957 in England and Wales. Model projections accurately mirror the failure of mass vaccination to increase the inter-epidemic period of the infection (three years) over that pertaining before control. The analysis suggests that this is due to the impact of partial vaccine efficacy. Projected trends to not accurately reflect the low levels of pertussis incidence reported between epidemics in the periods of high vaccine uptake. This is thought to arise from a combination of factors, including loss of natural and vaccine induced immunity, biases in case reporting (where reporting efficiency is positively associated with the incidence of pertussis), and seasonal variations in transmission. Model predictions suggest that the vaccination of 88% of each birth cohort before the age of 1 year will eliminate bacterial transmission, provided the vaccine confers lifelong protection against infection. If vaccine-induced immunity is significantly less than lifelong (or if vaccination fails to protect all its recipients) repeated cohort immunization is predicted to be necessary to eliminate transmission. Future research needs are discussed, and emphasis is placed on the need for more refined data on vaccine efficacy, the duration of natural and vaccine-induced immunity and the incidence of clinical pertussis and subclinical infections (perhaps by the development of reliable serological tests). Future mathematical models will need especially to incorporate seasonality in transmission.

scholarly journals Measles in developing countries. Part II. The predicted impact of mass vaccination

1988 ◽  
Vol 100 (3) ◽  
pp. 419-442 ◽  
Author(s):  
A. R. Mclean ◽  
R. M. Anderson
Keyword(s):  
Developing Countries ◽  
Measles Virus ◽  
Age Distribution ◽  
Case Fatality ◽  
Mass Vaccination ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Practical Significance ◽  
Epidemic Period ◽  
The Impact

SummaryA mathematical model is developed to mimic the transmission dynamics of the measles virus in communities in the developing world with high population growth rates and high case fatality rates. The model is used to compare the impacts of different mass vaccination programmes upon morbidity and mortality arising from infection by measles virus. Analyses identify three conclusions of practical significance to the design of optimal vaccination programmes. First, there is no single optimum age at which to vaccinate children for all urban and rural communities in developing countries. For a given community the best age at which to vaccinate depends critically on the age distribution of cases of infection prior to the introduction of control measures. Second, numerical studies predict that the introduction of mass vaccination will induce a temporary phase of very low incidence of infection before the system settles to a new pattern of recurrent epidemics. Mass vaccination acts to lengthen the inter-epidemic period in the postvaccination period when compared with that prevailing prior to control. Third, numerical simulations suggest that two-phase and two-stage vaccination programmes are of less benefit than one-stage programmes (achieving comparable coverage) aimed at young children. The paper ends with a discussion of the needs for: improved programmes of data collection; monitoring of the impact of current vaccination programmes; and the development of models that take account of viral transmission dynamics, host demography and economic factors.

Introduction to pertussis transmission and epidemiological dynamics

Pertussis ◽  
2018 ◽  
pp. 6-25
Author(s):  
Pejman Rohani ◽  
Samuel V. Scarpino
Keyword(s):  
Control Strategies ◽  
Age Distribution ◽  
Population Level ◽  
Vaccine Uptake ◽  
Effective Control ◽  
Transmission Potential ◽  
Epidemic Period ◽  
The Impact ◽  
Pertussis Epidemiology

Resolving the long-term, population-level consequences of changes in pertussis epidemiology, arising from bacterial evolution, shifts in vaccine-induced immunity, or changes in surveillance, are key challenges for devising effective control strategies. This chapter reviews some of the key features of pertussis epidemiology, together with the underlying epidemiological principles that set the context for their interpretation. These include the relationship between the age distribution of cases and pertussis transmission potential, the impact of vaccine uptake on incidence, periodicity and age incidence, as well as spatially explicit recurrent pertussis epidemics and associated extinction frequency. This review highlights some of the predictable and consistent aspects of pertussis epidemiology (e.g. the systematic increase in the inter-epidemic period with the introduction of whole-cell vaccines) and a number of important heterogeneities, including variations in contemporary patterns of incidence and geographic spread.

scholarly journals The epidemiology of mumps in the UK: a preliminary study of virus transmission, herd immunity and the potential impact of immunization

1987 ◽  
Vol 99 (1) ◽  
pp. 65-84 ◽  
Author(s):  
R. M. Anderson ◽  
J. A. Crombie ◽  
B. T. Grenfell
Keyword(s):  
Herd Immunity ◽  
Virus Transmission ◽  
Epidemiological Data ◽  
Mumps Virus ◽  
Mass Vaccination ◽  
Vaccine Uptake ◽  
Published Data ◽  
Epidemic Period ◽  
Potential Impact ◽  
Mumps Infection

SUMMARYMathematical models and statistical analyses of epidemiological data are employed to assess the potential impact of mass vaccination on the incidences of cases of mumps infection and cases of mumps related complications. The analyses reveal that in the United Kingdom the average age at infection with the mumps virus is currently between 6–7 years and that the inter-epidemic period of the infection is approximately 3 years. The critical level of vaccine uptake to eliminate mumps virus transmission is predicted to be approximately 85% of each cohort of boys and girls by the age of 2 years. Analyses of published data show that the risk of complication arising from mumps infection is markedly age- and sex-related. Model predictions suggest that the incidence of orchitis will be increased, over the level pertaining prior to mass vaccination, by levels of vaccine uptake (by 2 years of age) that are less than 70% of each yearly cohort of boys and girls. Moderate (over 00%) to high (75%) levels of vaccine uptake, however, are predicted to reduce the overall incidence of cases of mumps related complications (especially those with CNS involvement).

scholarly journals Impacts of vaccination and asymptomatic testing on SARS-CoV-2 transmission dynamics in a university setting

2021 ◽  
Author(s):  
Emily J Nixon ◽  
Amy C Thomas ◽  
Daniel A Stocks ◽  
Antoine M. G. Barreaux ◽  
Gibran Hemani ◽  
...  
Keyword(s):  
Cumulative Incidence ◽  
Compartmental Model ◽  
Student Population ◽  
University Student ◽  
Vaccine Uptake ◽  
Transmission Dynamics ◽  
Testing Uptake ◽  
University Settings ◽  
The Impact ◽  
University Setting

We investigate the impact of vaccination and asymptomatic testing uptake on SARS-CoV-2 transmission in a university student population using a stochastic compartmental model. We find that the magnitude and timing of outbreaks is highly variable under different vaccine uptake levels. With low level interventions (no asymptomatic testing, 30% vaccinated), 53-71% of students become infected during the first term; with high interventions (90% using asymptomatic testing, 90% vaccinated) cumulative incidence is 7-9%, with around 80% of these cases estimated to be asymptomatic. Asymptomatic testing is most useful when vaccine uptake is low: when 30% of students are vaccinated, 90% uptake of asymptomatic testing leads to almost half the case numbers. Under high levels of vaccine uptake (70-90%), case numbers in the student population are largely driven by community importation. Our findings suggest that vaccination is critical for controlling SARS-CoV-2 transmission in university settings with asymptomatic testing being a useful supporting measure.

scholarly journals Impact of vaccination and birth rate on the epidemiology of pertussis: a comparative study in 64 countries

2010 ◽  
Vol 277 (1698) ◽  
pp. 3239-3245 ◽  
Author(s):  
H. Broutin ◽  
C. Viboud ◽  
B. T. Grenfell ◽  
M. A. Miller ◽  
P. Rohani
Keyword(s):  
Birth Rate ◽  
Vaccine Coverage ◽  
Strong Association ◽  
Herd Immunity ◽  
Public Health Problem ◽  
Recruitment Rate ◽  
Vaccine Uptake ◽  
Important Public Health Problem ◽  
Epidemic Period ◽  
The Impact

Bordetella pertussis infection remains an important public health problem worldwide despite decades of routine vaccination. A key indicator of the impact of vaccination programmes is the inter-epidemic period, which is expected to increase with vaccine uptake if there is significant herd immunity. Based on empirical data from 64 countries across the five continents over the past 30–70 years, we document the observed relationship between the average inter-epidemic period, birth rate and vaccine coverage. We then use a mathematical model to explore the range of scenarios for duration of immunity and transmission resulting from repeat infections that are consistent with empirical evidence. Estimates of pertussis periodicity ranged between 2 and 4.6 years, with a strong association with susceptible recruitment rate, defined as birth rate × (1 − vaccine coverage). Periodicity increased by 1.27 years on average after the introduction of national vaccination programmes (95% CI: 1.13, 1.41 years), indicative of increased herd immunity. Mathematical models suggest that the observed patterns of pertussis periodicity are equally consistent with loss of immunity that is not as rapid as currently thought, or with negligible transmission generated by repeat infections. We conclude that both vaccine coverage and birth rate drive pertussis periodicity globally and that vaccination induces strong herd immunity effects. A better understanding of the role of repeat infections in pertussis transmission is critical to refine existing control strategies.

scholarly journals Impact of booster COVID-19 vaccine for Moroccan adults: A discrete age-structured model approach

2021 ◽  
Author(s):  
Aayah Hammoumi ◽  
Hanane Hmarrass ◽  
Redouane Qesmi
Keyword(s):  
Vaccine Efficacy ◽  
Adult Population ◽  
Herd Immunity ◽  
Vaccine Uptake ◽  
Vaccination Program ◽  
Model Parameters ◽  
Structured Model ◽  
Age Structured ◽  
Age Structured Model ◽  
The Impact

AbstractPublic health control strategies, such as lockdown, seem to be effective in reducing the spread of the pandemic, but are ineffective as a whole since lockdown is responsible of global economic crisis and badly lived by the majority of children and adults who have developed mental health disorders and familial problems as well. Thus, the development of a vaccine against COVID-19 is needed to control this disease. We have developed a discrete age-structured model and followed the Moroccan vaccination program to assess the impact of booster vaccination targeting Moroccan adults against COVID-19. Using the derived model, we estimated some relevant model parameters related to COVID-19 using collected cumulative mortality and reported Moroccan data. A control reproduction number Rc, which determines the necessary level of vaccine uptake that lead to COVID-19 eradication is determined. Furthermore, a herd immunity threshold above which the population can be protected from COVID-19 infection is derived. Analyzing the model, sufficient and necessary conditions for the eradication of the disease are obtained as well. Next, we perform numerical simulations to study the impact of several uptake levels of the potential vaccine on the persistence and the extinction of COVID-19 pandemic. Our results show that the COVID-19 is expected to last past 2021 in the absence of a vaccination program. Moreover, a vaccination of the adult population at rate 0.6% per day needs at least 67% of vaccine efficacy and 90% of immunogenicity rate to eradicate the disease. Using Sinopharm vaccine, the herd immunity can be achieved when about half of Moroccan adult population is immunized against the COVID-19. However, using Oxford-Astrazeneca vaccine, less than 60% of adult population must be immunized against the disease to achieve the herd immunity. Finally, if vaccine efficacy is about 80% and the immunogenicity is about 50% then vaccinating adults at rate of 0.6% per day could protect roughly 22% of children from COVID-19 infection.

scholarly journals Ignoring transmission dynamics leads to underestimation of the impact of a novel intervention against mosquito-borne disease

2021 ◽  
Author(s):  
Sean M. Cavany ◽  
John H Huber ◽  
Annaliese Wieler ◽  
Margaret Elliott ◽  
Quan Minh Tran ◽  
...  
Keyword(s):  
Public Health ◽  
Mathematical Models ◽  
Spatial Scale ◽  
Large Scale ◽  
Intracellular Bacterium ◽  
Health Needs ◽  
Transmission Dynamics ◽  
Multiple Sources ◽  
Recent Trial ◽  
The Impact

Wolbachia is an intracellular bacterium that many hope could have a major impact on dengue and other mosquito-borne diseases that are notoriously difficult to control. The balance of future investments in Wolbachia versus other public health needs will be informed to a great extent by efficacy estimates from large-scale trials, which can be affected by multiple sources of bias. We used mathematical models to quantify the possible magnitude of these biases, finding that efficacy would have been severely underestimated in a recent trial in Indonesia if the spatial scale of clusters had been smaller than it was. We also identified a previously unrecognized source of bias owing to the coupled nature of transmission dynamics across clusters. This too led to a consistent underestimate of the protection afforded by Wolbachia. Taken together, our findings suggest that this intervention may be even more promising than currently recognized.

scholarly journals Covid-19 disease dynamics with vaccination: The effect of uncertainty

2022 ◽  
Author(s):  
Nandadulal Bairagi ◽  
Abhijiit Majumder
Keyword(s):  
Mathematical Models ◽  
Vaccine Efficacy ◽  
Loss Rate ◽  
Vaccination Rate ◽  
Model Parameters ◽  
Extinction Time ◽  
Disease Eradication ◽  
Average Value ◽  
Force Of Infection ◽  
Induced Immunity

Rate parameters are critical in estimating the covid burden using mathematical models. In the Covid-19 mathematical models, these parameters are assumed to be constant. However, uncertainties in these rate parameters are almost inevitable. In this paper, we study a stochastic epidemic model of the SARS-CoV-2 virus infection in the presence of vaccination in which some parameters fluctuate around its average value. Our analysis shows that if the stochastic basic reproduction number (SBRN) of the system is greater than unity, then there is a stationary distribution, implying the long-time disease persistence. A sufficient condition for disease eradication is also prescribed for which the exposed class goes extinct, followed by the infected class. The disease eradication criterion may not hold if the rate of vaccine-induced immunity loss increases or/and the force of infection increases. Using the Indian Covid-19 data, we estimated the model parameters and showed the future disease progression in the presence of vaccination. The disease extinction time is estimated under various conditions. It is revealed that the mean extinction time is an increasing function of both the force of infection and immunity loss rate and shows the lognormal distribution. We point out that disease eradication might not be possible even at a higher vaccination rate if the vaccine-induced immunity loss rate is high. Our observation thus indicates the endemicity of the disease for the existing vaccine efficacy. The disease eradication is possible only with a higher vaccine efficacy or a reduced infection rate.

scholarly journals Assessing the impact of data aggregation in model predictions of HAT transmission and control activities

2019 ◽  
Author(s):  
M. Soledad Castaño ◽  
Martial L. Ndeffo-Mbah ◽  
Kat S. Rock ◽  
Cody Palmer ◽  
Edward Knock ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Data Aggregation ◽  
Time Series Data ◽  
Public Health Problem ◽  
Sleeping Sickness ◽  
Transmission Dynamics ◽  
World Health ◽  
Disease Stage ◽  
Series Data ◽  
The Impact

AbstractSince the turn of the century, the global community has made great progress towards the elimination of gambiense human African trypanosomiasis (HAT). Elimination programs, primarily relying on screening and treatment campaigns, have also created a rich database of HAT epidemiology. Mathematical models calibrated with these data can help to fill remaining gaps in our understanding of HAT transmission dynamics, including key operational research questions such as whether integrating vector control with current intervention strategies is needed to achieve HAT elimination. Here we explore, via an ensemble of models and simulation studies, which aspects of the available data and level of data aggregation, such as separation by disease stage, would be most useful for better understanding transmission dynamics and improving model reliability in making future predictions of control and elimination strategies.Author summaryHuman African tryposonomiasis (HAT), also known as sleeping sickness, is a parasitic disease with over 65 million people estimated to be living at risk of infection. Sleeping sickness consists of two stages: the first one is relatively mild but the second stage is usually fatal if untreated. The World Health Organization has targeted HAT for elimination as a public health problem by 2020 and for elimination of transmission by 2030. Regular monitoring updates indicate that 2020 elimination goals are likely to be achieved. This monitoring relies mainly on case report data that is collected through medical-based control activities — the main strategy employed so far in HAT control. This epidemiological data are also used to calibrate mathematical models that can be used to analyse current interventions and provide projections of potential intensified strategies.We investigated the role of the type and level of aggregation of this HAT case data on model calibrations and projections. We highlight that the lack of detailed epidemiological information, such as missing stage of disease or truncated time series data, impacts model recommendations for strategy choice: it can misrepresent the underlying HAT epidemiology (for example, the ratio of stage 1 to stage 2 cases) and increase uncertainty in predictions. Consistently including new data from control activities as well as enriching it through cross-sectional (e.g. demographic or behavioural data) and geo-located data is likely to improve modelling accuracy to support planning, monitoring and adapting HAT interventions.

Sign in / Sign up

Export Citation Format

Share Document