Real-world effectiveness of single-dose tafenoquine for P. vivax relapse prevention confirmed in retrospective observational study in Brazil

05 Mar 2024
two women in a rural health facility, Brazil

On 4th March 2024, The Lancet Infectious Diseases published operational real-world effectiveness data confirming the public health and patient benefits of using quantitative G6PD testing and tafenoquine in P. vivax malaria case management in Brazil. The findings lend further support to the introduction of these new tools in Brazil and potentially across South America for the prevention of malaria relapse.

The publication of these findings comes less than 3 weeks after the Lancet Global Health published the results of the Tafenoquine Roll-out STudy (TRuST), showing that the use of quantitative, point-of-care G6PD testing followed by P. vivax radical cure with tafenoquine or primaquine was highly feasible in the Brazilian Amazon. Tafenoquine has marketing authorization in Brazil, and in June 2023 the country became the first malaria-endemic country to adopt single-dose tafenoquine with G6PD testing for the treatment of relapsing P. vivax malaria nationwide.

‘The findings confirm that tafenoquine is an invaluable new asset for the management of malaria in Brazil.’ said Dr. Marcus Lacerda, ‘We look forward to seeing its wider use to support our malaria elimination goals.’

 The retrospective analysis found that single-dose tafenoquine delayed the time to first recurrence of P. vivax malaria infections to approximately 92 days versus 68 days with 7-day primaquine. The delay in time to first recurrence is important for patients, as anaemia – one of the most common complications of P. vivax infection – is cumulative, worsening with each episode of malaria. As the anaemia worsens people feel weaker and find it increasingly difficult to go about everyday tasks. Delaying the time to first recurrence means patients have a longer time to recover between these episodes.

The analysis further found that not only was single-dose tafenoquine as effective as 7-day primaquine (3.5 mg/kg total dose) at preventing P. vivax recurrence in patients aged at least 16 years who were G6PD normal compared at day 180, but it was also significantly more effective at day 90.

Of note, assessing drug efficacy in real-world studies is complicated for P. vivax malaria since it is not possible to differentiate cases of reinfection (due to new infectious mosquito bites) from relapse cases (where dormant parasites in the liver have not been successfully treated and so reactivate). For this reason, the study looked at recurrence, which covers both reinfections and relapses.

Visit the Lancet Infectious Diseases website to read the study in full.