Photo: First online presentation after the shelter-in-place order was declared in California – Davis, CA, USA.

"I have no idea what’s awaiting me, or what will happen when this all ends. For the moment I know this: there are sick people and they need curing." ―Albert Camus, The Plague

Peer-Reviewed Publications

Castonguay, F.M., Blackwood, J.C., Howerton, E., Shea, K., Sims, C. & Sanchirico, J.N. Optimal spatial evaluation of a pro rata vaccine distribution rule for COVID-19. Sci Rep 13, 2194 (2023).

Optimal Spatial Evaluation of a Pro Rata Vaccine Distribution Rule for COVID-19

Job Market Paper. Link to published paper here.

Abstract: The COVID-19 Vaccines Global Access (COVAX) is a World Health Organization (WHO) initiative that aims for an equitable access of COVID-19 vaccines. Despite potential heterogeneous infection levels across a country, countries receiving allotments of vaccines may follow WHO’s allocation guidelines and distribute vaccines based on a jurisdictions’ relative population size. Utilizing economic–epidemiological modeling, we benchmark the performance of this pro rata allocation rule by comparing it to an optimal one that minimizes the economic damages and expenditures over time, including a penalty representing the social costs of deviating from the pro rata strategy. The pro rata rule performs better when the duration of naturally- and vaccine-acquired immunity is short, when there is population mixing, when the supply of vaccine is high, and when there is minimal heterogeneity in demographics. Despite behavioral and epidemiological uncertainty diminishing the performance of the optimal allocation, it generally outperforms the pro rata vaccine distribution rule.

Figure: This schematic shows the model interventions and disease transmission pathways for our model of COVID-19. The full lines represent the transition between, or out of, compartments while the dotted lines represent contact between susceptible and infected individuals. Black lines represent situations that do not vary, while yellow lines represent key factors that we vary in our model to see how they impact our results. The green lines represent the vaccine and the red line represents mortality.

Significance

While most of the discussion around the allocation of COVID-19 vaccines has focused on what segment of the population to prioritize, our research answers an important question that has received much less attention in the literature and that is becoming increasingly important now that developing countries are receiving allotments of vaccines via COVAX: how much of a scarce vaccine should we allocate across jurisdictions within a country and within each jurisdiction? Should we allocate based on relative population size, some normalized measure of disease burden (e.g., cases per 100,000), or some other allocation rule? We show that while a pro rata vaccine distribution based on relative population size prioritizes equity of distribution, it only implies equity of outcomes under very strict conditions. As such, addressing this question could prove to be as significant in reducing the economic and public health burden of COVID-19 and other infectious diseases as determining which segment of the population to prioritize. However, despite potential economic and public health benefits of deviating from this prevailing pro rata rule, the uncertainty around behavioral and epidemiological factors needed to determine the optimal allocation diminishes the feasibility, and potentially the performance, of the optimal allocation.

Castonguay, F. M., Sokolow, S. H., De Leo, G. A., & Sanchirico, J. N. (2020). Cost-effectiveness of combining drug and environmental treatments for environmentally transmitted diseases. Proceedings of the Royal Society B, 287(1933), 20200966.

Link to the paper here.

Figure: Modeled treatment options, i.e. Mass Drug Administration (MDA) and Environmental Treatments (EnvTre), and transmission pathways for schistosomiasis (Castonguay et al., 2020). The importance of the trade-off between environmental treatments (e.g. pesticides) and traditional public health interventions (e.g. drug treatment) for environmentally transmitted diseases—such as schistosomiasis—is such that separate guidelines for drug and environmental treatments, as currently recommended by the World Health Organization, lead to the overuse of public funds and treatments which, according to our results, contributes to a misallocation of approximately 1.75 billion US dollar over a 50-year period.

Castonguay, F. M., & Lasserre, P. (2019). L’exploitation de ressources naturelles non renouvelables en asymétrie d'information. L'Actualité économique, 95(2-3).

Link to the paper in French here; link to the working paper in English here.

Figure: Effect of privately known exploration and extraction costs on the extensive margin (EM) of a nonrenewable natural resource (Castonguay and Lasserre, 2016, 2019; note that this figure was adapted to avoid paper-specific notation and to be in English). From this figure, we can see that compared with the symmetric information first best, avoiding adverse selection in extraction requires the optimum mechanism to increase discoveries by the lowest cost type and possibly others. This is tempered by a countervailing effect stemming from information asymmetry in exploration that tends to reduce discoveries, especially by higher cost types. Information asymmetry entails abandoned reserves (because it can push the EM above the one in the symmetric case), excessive use of low-cost exploration prospects (since exploration effort is higher for low values of the marginal cost of exploration), and inefficient levels of technological sophistication in the exploration and extraction sectors (since the EM is affected by the presence of information asymmetry).

Other Publication

Castonguay, F., & Lasserre, P. (2016). Resource Agency Relationship with Privately Known Exploration and Extraction Costs. CIRANO Scientific Series, 2016s(56).

Link to the working paper here (same as above), inspired by my Master's thesis.

Work in Progress

Ecological Interventions to Fight Diseases: When Objectives Are Misaligned

Abstract: Ecological interventions are nonpharmaceutical actions that individuals and communities can take to reduce disease transmission by considering the interactions among the different disease-carrying organisms and their environment. They are receiving increasing interest by both researchers and practitioners to prevent and manage environmentally transmitted diseases because of their potential to maintain disease burden under control in a decentralized way. When the main drivers of such intervention are the economic benefits derived from undertaking the activity, ecological interventions also have the potential to be sustainable. While the economic incentives are key in making such interventions viable, they can also have unintended consequences that hinders their public health purpose. In this paper, we investigate the consequences that profit-maximizing behavior has on the transmission of an environmentally transmitted disease, using schistosomiasis and prawn aquaculture as a case study. Freshwater prawns, a natural predator of the intermediate host snails, is a food source for local populations and maintain disease prevalence at low levels in the environment. We simulate the behavior of a profit-maximizing aquaculture farmer whose activity has the potential to create ancillary public health benefits, but whose decision-making concerning supplemental feeding can mitigate these same public health benefits. Our results suggest that it may be necessary for policymakers to incentivize aquaculture farmers in order to reap any indirect public health benefits from their activity.

Building a Simple Model to Assess the Impact of Case Investigation and Contact Tracing for Sexually Transmitted Diseases: Lessons from COVID-19

The Public Health Impact of COVID-19 Variants of Concern on the Effectiveness of Contact Tracing: Evidence from the Delta Surge in Vermont

Estimated Public Health Impact of a Concurrent Mask and Vaccine Mandate in Illinois

Impact of Adapting COVID-19 Contact Tracing Protocols to Periods of High Transmission in Philadelphia, June – October 2021

Risk-benefit Analysis of ACAM2000 Vaccination for Use as Pre-exposure Prophylaxis Against Monkeypox in the United States

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