Epidemic influenza in Greater London

Spicer, C. C.; Lawrence, C. J.

doi:10.1017/s0022172400060988

Cited by 32 publications

(20 citation statements)

References 9 publications

(4 reference statements)

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“…An earlier study proposed estimates higher than ours (range 1.4-2.6) for several consecutive influenza seasons in England and Wales [15,16], however the exact quantity measured in this work remains controversial [14,31]. A particularly high R p estimate (R p > 2.0) has also been reported for the 1951 influenza epidemic in England and Canada, however, this epidemic was associated with unusually high mortality and transmissibility locally [19,22].…”

Section: Discussioncontrasting

confidence: 44%

“…Unlike P&I data, influenza-specific death time-series do not require modelling a seasonal baseline prior to fitting a transmission model [15][16][17]19]. It is reassuring that mean and individual-season estimates using influenza-specific and P&I mortality data were similar for the two countries where sufficient years were available for comparison (United States, France).…”

Section: Discussionmentioning

confidence: 97%

“…The transmission rate and the initial numbers of individuals in the exposed E(0) and infectious I(0) categories at the beginning of each influenza season were estimated by least squares fitting to the cumulative number of weekly influenza-related deaths or cases, during the initial take-off of the epidemic. The advantage of using the cumulative over the weekly number of deaths is that the former smoothes out demographic noise and reporting delays [16]. Due to the short latent period for influenza (1.9 days), we assumed E(0) = I(0); this simplification allowed us to estimate only two parameters from the exponential growth phase of the epidemic.…”

Section: Parameter Estimationmentioning

confidence: 99%

“…Past studies have estimated the reproduction number of individual influenza seasons, in particular for pandemics [11][12][13][14][15][16][17][18][19]. However, no study has yet reported estimates of the reproduction number for several countries and consecutive influenza seasons in the interpandemic period, where a fraction of the population is immune due to previous influenza exposure or vaccination.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

2007

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SUMMARYRecurrent epidemics of influenza are observed seasonally around the world with considerable health and economic consequences. A key quantity for the control of infectious diseases is the reproduction number, which measures the transmissibility of a pathogen and determines the magnitude of public health interventions necessary to control epidemics. Here we applied a simple epidemic model to weekly indicators of influenza mortality to estimate the reproduction numbers of seasonal influenza epidemics spanning three decades in the United States, France, and Australia. We found similar distributions of reproduction number estimates in the three countries, with mean value 1.3 and important year-to-year variability (range 0.9-2.1). Estimates derived from two different mortality indicators (pneumonia and influenza excess deaths and influenza-specific deaths) were in close agreement for the United States (correlation = 0.61, P < 0.001) and France (correlation = 0.79, P < 0.001), but not Australia. Interestingly, high prevalence of A/H3N2 influenza viruses was associated with high transmission seasons (P = 0.006), while B viruses were more prevalent in low transmission seasons (P = 0.004). The current vaccination strategy targeted at people at highest risk of severe disease outcome is suboptimal because current vaccines are poorly immunogenic in these population groups. Our results suggest that interrupting transmission of seasonal influenza would require a relatively high vaccination coverage (> 60 %) in healthy individuals who respond well to vaccine, in addition to periodic re-vaccination due to evolving viral antigens and waning population immunity.

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Section: Discussioncontrasting

confidence: 44%

Section: Discussionmentioning

confidence: 97%

Section: Parameter Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

2007

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“…Estimates based on the first pandemic after a shift suggests that ρ ≈ 2 − 4 for all three subtypes of influenza A (Mills et al, 2004;Spicer and Lawrence, 1984). For such values of ρ moderate levels of permanent 20 and temporary cross-immunity can explain the lack of branches in the flu tree.…”

Section: Discussionmentioning

confidence: 99%

Shaping the phylogenetic tree of influenza by cross-immunity

Andreasen

Sasaki

2006

Theoretical Population Biology

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Modelling the 1985 influenza epidemic in France

Flahault

Letrait

Blin

et al. 1988

Statistics in Medicine

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The Rvachev-Baroyan-Longini model is a space-time predictive model of the spread of influenza epidemics. It has been applied to 128 cities of the USSR, and more recently, to forecasting the spread of the pandemic of 1968-1969 throughout 52 large cities. It is a deterministic, mass-action, space and time continuous model. The model has been applied to the simulation of the influenza epidemic of 1984-1985 in the 22 French Metropolitan districts and results are presented. Estimates of the parameters of the model were made using the French Communicable Diseases Network data. These parameters are the contact rate, a, (estimate = 0.55) which is the number of people with whom an infectious individual will make contact daily sufficient to pass infection and the infectious period, 1/b, estimated as 2.49 days. The mean annual railroad passenger traffic from district i to district j varies from 0 to 1,991,000 persons depending on the districts. The computer spread of the epidemic is presented on weekly maps. Results are also presented on district charts, giving the size of district epidemics and the time of peak of the epidemic. The precision of the computer fittings was judged satisfactory by the calculated size of peak differing from the real one by less than 100 per cent, in 17 out of 18 districts, and by the calculated time of peak differing from the observed by less than two weeks in 14 out of 18 districts. Although precision could be improved with more detailed information about passenger traffic, the French use of the model has been satisfactory.

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Epidemic influenza in Greater London

Cited by 32 publications

References 9 publications

Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

Seasonal influenza in the United States, France, and Australia: transmission and prospects for control

Shaping the phylogenetic tree of influenza by cross-immunity

Modelling the 1985 influenza epidemic in France

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