Dados do Trabalho

Título

The 2023 chikungunya outbreak in Paraguay and the potential impact of new vaccines

Introdução

With Chikungunya vaccines finally available, we now have tools to battle outbreaks, although it remains unclear if vaccines deployed during an ongoing epidemic could be used to effectively reduce disease burden. 

Objetivo (s)

We used a large outbreak in Paraguay in 2022-2023 (123,781reported cases and 298 deaths during the study period) to understand how a vaccine could be used in the future.

Material e Métodos

To understand the underlying burden of infection from the outbreak, we first conducted a seroprevalence study in four of the five subregions of Paraguay to estimate age-specific case detection probabilities and infection fatality ratios. We then used mathematical models to quantify the impact of a vaccine had it been available at the time. 

Resultados e Conclusão

We estimate that 34% of the population was seropositive following the outbreak (340/1001 samples), compared to <5% prior to the outbreak, with seropositivity greatest in the Centro Este subregion (47%). We estimate that the surveillance system detected 5.4% of infected individuals and the average IFR was 0.013%. Had a chikungunya vaccine been available at the time, we estimate a reactive campaign would have prevented 570,000 infections (2,500 per 10,000 doses used) and 73 deaths (0.32 per10,000 doses used) and required 2.3 million doses for 40% coverage. However, delays in initiating a campaign would significantly reduce the impact of the vaccine. These findings provide a robust understanding of the underlying epidemiology and suggest the new vaccine can be effective in a reactive campaign if the outbreak is detected in a timely manner.

Palavras Chave

Chikungunya; Paraguay; Modelos; Vacina