Imperial College London


Business School

Visiting Researcher



k.lau15 CV




349ACE ExtensionSouth Kensington Campus





Publication Type

7 results found

DAeth J, Ghosal S, Grimm F, Haw D, Koca E, Lau K, Liu H, Moret S, Rizmie D, Smith P, Forchini G, Miraldo M, Wiesemann Wet al., 2023, Optimal hospital care scheduling during the SARS-CoV-2 pandemic, Management Science, ISSN: 0025-1909

The COVID-19 pandemic has seen dramatic demand surges for hospital care that have placed a severe strain on health systems worldwide. As a result, policy makers are faced with the challenge of managing scarce hospital capacity so as to reduce the backlog of non-COVID patients whilst maintaining the ability to respond to any potential future increases in demand for COVID care. In this paper, we propose a nation-wide prioritization scheme that models each individual patient as a dynamic program whose states encode the patient’s health and treatment condition, whose actions describe the available treatment options, whose transition probabilities characterize the stochastic evolution of the patient’s health and whose rewards encode the contribution to the overall objectives of the health system. The individual patients’ dynamic programs are coupled through constraints on the available resources, such as hospital beds, doctors and nurses. We show that the overall problem can be modeled as a grouped weakly coupled dynamic program for which we determine near-optimal solutions through a fluid approximation. Our case study for the National Health Service in England shows how years of life can be gained by prioritizing specific disease types over COVID patients, such as injury & poisoning, diseases of the respiratory system, diseases of the circulatory system, diseases of the digestive system and cancer.

Journal article

Galizzi M, Lau K, Miraldo M, Hauck Ket al., 2022, Bandwagoning, free-riding and heterogeneity in influenza vaccine decisions: an online experiment, Health Economics, Vol: 31, Pages: 614-646, ISSN: 1057-9230

‘Nudge’-based social norms messages conveying high population influenza vaccination coverage levels can encourage vaccination due to bandwagoning effects but also discourage vaccination due to free-riding effects on low risk of infection, making their impact on vaccination uptake ambiguous.We develop a theoretical framework to capture heterogeneity around vaccination behaviors, and empirically measure the causal effects of different messages about vaccination coverage rates on four self-reported and behavioral vaccination intention measures. In an online experiment, N = 1,365 UK adults are randomly assigned to one of seven treatment groups with different messages about their social environment’s coverage rate (varied between 10% and 95%), or a control group with no message. We find that treated groups have significantly greater vaccination intention than the control. Treatment effects increase with the coverage rate up to a 75% level, consistent with a bandwagoning effect. For coverage rates above 75%, the treatment effects, albeit still positive, stop increasing and remain flat (or even decline). Our results suggest that, at higher coverage rates, free-riding behavior may partially crowd out bandwagoning effects of coverage rates messages. We also find significant heterogeneity of these effects depending on the invidual perceptions of risks of infection and of the coverage rates.

Journal article

DAeth J, Ghosal S, Grimm F, Haw D, Koca E, Lau K, Moret S, Rizmie D, Deeny S, Perez-Guzman P, Ferguson N, Hauck K, Smith P, Forchini G, Wiesemann W, Miraldo Met al., 2021, Optimal national prioritization policies for hospital care during the SARS-CoV-2 pandemic, Nature Computational Science, Vol: 1, Pages: 521-531, ISSN: 2662-8457

In response to unprecedent surges in the demand for hospital care during the SARS-CoV-2 pandemic, health systems have prioritized COVID patients to life-saving hospital care to the detriment of other patients. In contrast to these ad hoc policies, we develop a linear programming framework to optimally schedule elective procedures and allocate hospital beds among all planned and emergency patients to minimize years of life lost. Leveraging a large dataset of administrative patient medical records, we apply our framework to the National Health System in England and show that an extra 50,750-5,891,608 years of life can be gained in comparison to prioritization policies that reflect those implemented during the pandemic. Significant health gains are observed for neoplasms, diseases of the digestive system, and injuries & poisoning. Our open-source framework provides a computationally efficient approximation of a large-scale discrete optimization problem that can be applied globally to support national-level care prioritization policies.

Journal article

Lau K, Dorigatti I, Miraldo M, Hauck Ket al., 2021, SARIMA-modelled greater severity and mortality during the 2010/11 post-pandemic influenza season compared to the 2009 H1N1 pandemic in English hospitals, International Journal of Infectious Diseases, Vol: 105, Pages: 161-171, ISSN: 1201-9712

ObjectiveThe COVID-19 pandemic demonstrates the need for understanding pathways to healthcare demand, morbidity, and mortality of pandemic patients. We estimate H1N1 (1) hospitalization rates, (2) severity rates (length of stay, ventilation, pneumonia, and death) of those hospitalized, (3) mortality rates, and (4) time lags between infections and hospitalizations during the pandemic (June 2009 to March 2010) and post-pandemic influenza season (November 2010 to February 2011) in England.MethodsEstimates of H1N1 infections from a dynamic transmission model are combined with hospitalizations and severity using time series econometric analyses of administrative patient-level hospital data.ResultsHospitalization rates were 34% higher and severity rates of those hospitalized were 20%–90% higher in the post-pandemic period than the pandemic. Adults (45–64-years-old) had the highest ventilation and pneumonia hospitalization rates. Hospitalizations did not lag infection during the pandemic for the young (<24-years-old) but lagged by one or more weeks for all ages in the post-pandemic period.DiscussionThe post-pandemic flu season exhibited heightened H1N1 severity, long after the pandemic was declared over. Policymakers should remain vigilant even after pandemics seem to have subsided. Analysis of administrative hospital data and epidemiological modelling estimates can provide valuable insights to inform responses to COVID-19 and future influenza and other disease pandemics.

Journal article

D'Aeth J, Ghosal S, Grimm F, Haw D, Koca E, Lau K, Moret S, Rizmie D, Deeny S, Perez Guzman P, Ferguson N, Hauck K, Smith P, Wiesemann W, Forchini G, Miraldo Met al., 2020, Report 40: Optimal scheduling rules for elective care to minimize years of life lost during the SARS-CoV-2 pandemic: an application to England

SummaryCountries have deployed a wide range of policies to prioritize patients to hospital care to address unprecedent surges in demand during the course of the pandemic. Those policies included postponing planned hospital care for non-emergency cases and rationing critical care.We develop a model to optimally schedule elective hospitalizations and allocate hospital general and critical care beds to planned and emergency patients in England during the pandemic. We apply the model to NHS England data and show that optimized scheduling leads to lower years of life lost and costs than policies that reflect those implemented in England during the pandemic. Overall across all disease areas the model enables an extra 50,750 - 5,891,608 years of life gained when compared to standard policies, depending on the scenarios. Especially large gains in years of life are seen for neoplasms, diseases of the digestive system, and injuries & poisoning.


Lau K, Miraldo M, Galizzi MM, Hauck Ket al., 2019, Social norms and free-riding in influenza vaccine decisions in the UK: an online experiment, National Conference on Public Health Science Dedicated to New Research in UK Public Health, Publisher: Elsevier, Pages: S65-S65, ISSN: 0140-6736

Conference paper

Lau K, Hauck K, Miraldo M, 2019, Excess influenza hospital admissions and costs due to the 2009 H1N1 pandemic in England, HEALTH ECONOMICS, Vol: 28, Pages: 175-188, ISSN: 1057-9230

Journal article

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