Research

Current and recent projects:

• Respiratory virus forecasting: The main focus of my current research is to create robust short-term forecasting models to predict trends in influenza, SARS-CoV-2, and RSV hospitalizations in Utah, in partnership with the Utah Department of Health and Human Services. We are examining the effects of surveillance drift in our datasets over time, which consist of hospitalizations, syndromic surveillance, and wastewater data for the State. This bridges methodological advances in infectious disease modeling with real-world public health practice, providing decision-ready tools that support hospital preparedness, resource allocation, and targeted local response.
• One Health and malaria risk: Use of zooprophylaxis as a malaria control strategy has been recommended historically, but a complex relationship exists between animal ownership and malaria infection, with mixed associations described in the literature. My team used cross-sectional multi-country, multi-year data across Africa from the Demographic and Health Surveys (DHS) Program and Bayesian hierarchical models to assess the relationship between malaria infection and household ownership of six common types of livestock. Furthermore, we examined how malaria and household livestock ownership associations vary across space and time and what factors may modify those associations. Use of these methods allows for study of this One Health topic on a large geographic and temporal scale and can inform the identification of areas which may be suitable for further analysis of zooprophylactic strategies.
• R21/Matrix-M and RTS,S/AS01 malaria vaccines: Two malaria vaccines have been recently recommended by the World Health Organization for implementation among young children in sub-Saharan Africa. With my colleagues, I modeled the cost-effectiveness of these vaccines relative to the scale-up of existing interventions such as insecticide-treated bed nets and seasonal malaria chemoprevention.
• Metapopulation models in sub-Saharan Africa: Often groups primarily model one specific country or administrative unit setting at a time. However, malaria is geographically heterogenous, and malaria transmission in one area affects the transmission levels in other areas due to mosquito and human movement. I developed a metapopulation model to be able to capture interaction between settings. The goal is to be able to look at areas of high transmission which border areas of near-elimination (e.g. Mozambique and South Africa) to better inform border strategies.
• Gender inequality in publications: Women and ethnic minorities are underrepresented among authors of scientific publications. In both the UK and the US, there are also fewer women appointed to full-time faculty than men, despite more women obtaining bachelor's, master's, and doctoral degrees than men, a trend which also follows for ethnic minority groups. I worked with a team to characterize the representation of women and ethnic minorities at Imperial College London's School of Public Health. We are hoping that this work will inform strategies to increase representation and remove barriers to publication and career advancement in our field.
• Community engagement: Innovation in malaria tools and increased funding can save more than 13.2 million lives over the next 15 years. I was the lead malaria modeler contributing to the "Zero Malaria Experience", a film collaboration and public interactive installation with Malaria No More UK, the Mill (a creative community), David Beckham, and global public health leaders. Check it out!

Select publications:

Estimating the potential impact of surveillance test-and-treat posts to reduce malaria in border regions in sub-Saharan Africa: a modelling study.
Topazian HM, Charles GD, Schmit N, Pianella M, Marshall JM, Kleinschmidt I, Hauck K, Ghani AC (2025) Malaria Journal 24:127.

The public health impact and cost-effectiveness of the R21/Matrix-M malaria vaccine: a mathematical modelling study.
Schmit N*, Topazian HM*, Natama MH, Bellamy D, Traoré O, Some AN, Rouamba T, Tahita MC, Bonko MA, Sourabié A, Sorgho H, Stockdale L, Provstgaard-Morys S, Aboagye J, Woods D, Rapi K, Datoo MS, Ramos Lopez F, Charles G, McCain K, Ouédraogo J, Hamaluba M, Ologu A, Dicko A, Tinto H, Hill AVS, Ewer K, Ghani A, Winskill P (2023) The Lancet Infectious Diseases 24(5):465-475.

Resource allocation strategies for insecticide-treated bed nets to achieve malaria eradication.
Schmit N*, Topazian HM*, Pianella M*, Charles GD, Winskill P, White MT, Hauck K, Ghani AC (2023) elife 12:RP88283.

Modelling the relative cost-effectiveness of the RTS,S/AS01 malaria vaccine compared to investment in vector control or chemoprophylaxis.
Topazian HM, Schmit N, Gerard-Ursin I, Charles GD, Thompson H, Ghani AC, Winskill P (2023) Vaccine 41(20):3215-3223.

No evidence of sustained nonzoonotic Plasmodium knowlesi transmission in Malaysia from modelling malaria case data.
Fornace KM, Topazian HM, Routledge I, Asyraf S, Kelip J, Lindblade KA, Jaeffree MS, Cuenca PR, Bhatt S, Ahmed K, Ghani AC, Drakeley C (2023) Nature Communications 41(20):3215-3223.

Low complexity of infection is associated with molecular persistence of Plasmodium falciparum in Kenya and Tanzania.
Topazian HM, Moser KA, Ngasala B, Oluoch PO, Forconi CS, Mhamilawa LE, Aydemir O, Kharabora O, Deutsch-Feldman M, Read AF, Denton M, Lorenzo A, Mideo N, Ogutu B, Moormann AM, Mårtensson A, Odwar B, Bailey JA, Akala H, Ong’echa JM, Juliano JJ (2022) Frontiers in Epidemiology 2:852237.

Effectiveness of a national mass distribution campaign of long-lasting insecticide-treated nets and indoor residual spraying on clinical malaria in Malawi, 2018–2020.
Topazian HM*, Gumbo A*, Edwards JK, Brandt K, Goel V, Kayange M, Mvalo T, Emch M, Pettifor A, Smith J, Juliano JJ, Hoffman I (2021) BMJ Global Health 6:e005447.

Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015-2016.
Topazian HM, Gumbo A, Puerto-Meredith S, Njiko R, Mwanza A, Kayange M, Mwalilino D, Mvula B, Tegha G, Mvalo T, Edwards JK, Emch M, Pettifor A, Smith JS, Hoffman I, Meshnick SR, Juliano JJ (2020) Scientific Reports 10:18740.

Household prevalence of P. falciparum, P. vivax, and P. ovale in the Democratic Republic of the Congo, 2013-2014.
Mitchell CL*, Topazian HM*, Brazeau NF, Deutsch-Feldman M, Muwonga J, Sompwe E, Tshefu AK, Mwandagalirwa MK, Parr JB, Juliano JJ (2021) Clinical Infectious Diseases 73(11):e3966-3969.

* Equal contribution