Study models how malaria vaccines can help mitigate climate-driven breaks in disease control
malaria vaccines
-- offering protection up to 10 months -- could help mitigate disruptions to disease control measures because of extreme weather events.
Malaria -- a mosquito-borne infectious disease -- is a serious public health concern, with climate change-driven temperatures and rainfall creating conditions more conducive for mosquitoes to thrive and spread disease, especially in tropical countries.
Researchers from the US and Madagascar in Africa said that extreme weather events, such as tropical cyclones, can hit public health infrastructure and limit people's access to malaria prevention and treatment -- this can increase infection risk, especially in high-burden regions where continuity of care and disease control is critical.
However, despite concerns, data on how climate-related disruptions affect malaria control remain scarce, they said.
The study, published in the journal Science, analysed 20,718 observations of malaria infection -- collected from 500 households in the African country -- before and after cyclones Batsirai (2022) and Freddy (2023) to understand how well various malaria interventions performed under the strain of extreme weather events.
"In the aftermath, infection rates by the mosquito-vectored parasite increased to 10 per cent for school-aged children within three months as mosquito and malaria control activities were interrupted," the authors wrote.
Brief, under-a-month-long breaks in malaria control activities, such as use of preventive medications, resulted in "rapid rebounds in infection" -- up to half of school children and over a third of younger ones were infected in high-transmission areas, the team said.
Modelling strategies that may mitigate these effects in the aftermath of cyclones, the authors found that the recently introduced, WHO-recommended malaria vaccines -- 'RTS,S' and 'R21' -- could significantly reduce infection rates and help in sustaining disease control measures during breaks caused by extreme weather conditions.
A vaccine coverage of 70 per cent in the population was related with a 42-52 per cent reduction in infections, the models showed.
Given the figures reported by the country for routine childhood immunisation programmes, 70 per cent coverage in the population is plausible, the authors said.
They wrote, "When 70 per cent of the targeted population has completed the full course for a vaccine with effectiveness of 61 to 74 per cent (reported for the R21 vaccine in phase 3 trials) before the disruptive event, a 42.7 to 51.8 per cent reduction in the expected proportion of symptomatic infections is expected."
However, the team also noted that vaccines alone are not enough to arrest disease spread and that layered strategies "combining vaccines, drug-based prevention, and traditional tools like bed nets are essential, especially in high-transmission areas where malaria remains persistent".
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