US approves first Chikungunya vaccine amid growing global health concerns

The United States Food and Drug Administration (FDA) on November 9 approved the world's inaugural vaccine targeting chikungunya, a virus transmitted by infected mosquitoes, as per an APF report. The move comes as the US drug regulator identified chikungunya as "an emerging global health threat", it added.

Developed by Europe's Valneva, the vaccine will be marketed as Ixchiq. The company has secured approval for individuals aged 18 and above, an age group that faces elevated risk of exposure, according to the FDA.

Ixchiq, administered in a single dose, contains a live, weakened version of the chikungunya virus, following the standard approach for vaccines. Two clinical trials conducted in North America on 3,500 participants revealed common side effects such as headache, fatigue, muscle and joint pain, fever, and nausea. Serious reactions were reported in 1.6 percent of recipients, with two cases requiring hospitalization.

Valneva has also submitted an application for authorization with the European Medicines Agency (EMA). The US FDA greenlight is anticipated to expedite the vaccine's deployment, particularly in countries where the chikungunya virus is prevalent.

Global prevalence, unmet medical need

The virus, causing fever and severe joint pain, is commonly found in tropical and subtropical regions of Africa, Southeast Asia, and parts of the Americas. The FDA highlighted the global rise in chikungunya cases, reporting over five million instances in the past 15 years, the report said.

Chikungunya symptoms can persist for months or even years, although fatalities are rare. Currently, there is no specific drug for treating chikungunya, with pain and fever relief medications being the common recourse. Until now, the primary preventive measure was to avoid mosquito bites.

Senior FDA official Peter Marks in a statement emphasised the severity of the disease, particularly for older adults and individuals with underlying medical conditions. "The approval is viewed as a crucial step in addressing an unmet medical need and advancing the prevention of this potentially debilitating disease," he added.

First identified in Tanzania in 1952, chikungunya has spread to over 110 countries, according to the World Health Organisation (WHO). Experts express concerns about its potential as a future pandemic threat, particularly with changing climates influencing the mosquitoes' distribution.

Efficacy at 98%, finds study

Earlier on June 12, a clinical study on the vaccine, published in The Lancet said it demonstrated "highly protective" results in its Phase III human trial. The vaccine exhibited an impressive response rate of 98.9 percent in participants 28 days after a single administration, it noted.

The live-attenuated vaccine, VLA1553, is based on the La Reunion strain of chikungunya, specifically the East Central South African genotype. According to the research paper, the vaccine candidate was "generally well tolerated and produced an immune response in 99 percent (263/266) of participants."

Martina Schneider, the lead author of the paper and clinical strategy manager at Valneva, had then noted that this could be the first chikungunya virus vaccine candidate for active immunisation of travellers to and residents of endemic areas or areas at risk for an upcoming outbreak. She also emphasized the importance of good antibody persistence, a characteristic expected from a live-attenuated vaccine, given the disease's unstable epidemiology.