Medical researchers have developed the first ever chikungunya vaccine, which they say is safe and effective as the vaccine does not cause any symptoms in humans. A chikungunya vaccine will be welcome in India where outbreaks of the mosquito-borne disease have become routine in the monsoon months.

In 2016, India recorded 55,639 cases of clinically suspected chikungunya, according to provisional government data till the second week of December. That is almost twice the number of cases in 2015. Delhi was hit particularly hard with more than 12,000 cases and, for the first time, the city recorded deaths of at least 19 people due to chikungunya-related complications. Chikungunya normally manifests as fever and severe joint pain and death from the disease is rare.

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Researchers from the University of Texas have now developed a vaccine for chikungunya made from an insect-specific virus and showed that the vaccine quickly produces a strong immune defense that protects mice and nonhuman primates exposed to the chikungunya virus.

A special feature of the new chikungunya vaccine is that is has been developed using a hybrid Eilat-Chikungunya virus, instead of the weakened chikungunya virus alone, to trigger an immune response. The Eilat-Chikungunya vaccine is structurally identical to the natural chikungunya virus but while it replicates well in mosquito cells and cannot replicate in mammals. This protects mammals, including humans, from symptoms of the disease and the risks of infection in case the vaccine preparation has been faulty.

The study published in Nature Medicine shows that the Eilat-Chikungunya vaccine induced virus-neutralising antibodies within four days of a dose and the antibodies lasted for more than 290 days. The antibodies provided complete protection against chikungunya in two mouse models. In non-human primates, it induced rapid immunity with subjects showing no sign of illness or the virus in the blood after infection.