•        A phase 3 randomized, controlled trial reported on 12th June 2023 in The Lancet found that 98.9% of people who got a single dose of the VLA1553 chikungunya virus vaccine candidate made neutralizing antibodies 28 days later. •        What is Chikungunya Infection?  o        TRANSMISSION : Chikungunya virus is typically spread to humans through the bite of an infected mosquito, especially Aedes aegypti and Aedes albopictus.  o        Humans are the primary host of chikungunya virus during epidemic seasons. o        Mosquitoes become infected when they feed on a person who already has the virus. o        SYMPTOMS : most common -fever and joint pain. Other symptoms may include headache, muscle pain, joint swelling, or rash. o        PREVENTION : The easiest approach to prevent chikungunya is to protect yourself from mosquito bites. Use insect repellent, wear long-sleeved shirts and pants, treat clothing and gear, and take precautions to reduce mosquitoes indoors and outside. o        At the present time, neither a vaccine nor any medication is available for the treatment of chikungunya. o        Outbreaks have occurred in countries in Africa, Americas, Asia, Europe, and the Caribbean, Indian and Pacific Oceans.  o        There is a danger the virus will be spread to unaffected areas by infected travelers. •        A team lead by vaccine creator Valneva in Vienna investigated immunological responses to VLA1553 in 362 adults (266 vaccination recipients and 96 placebo recipients) at 43 US trial sites from September 17, 2020, to April 10, 2021, plus a broader safety cohort. •        This phase 3 study was double-blind, randomised, and took place in 43 professional vaccine trial sites in the USA.  •        Participants had to be healthy and at least 18 years old to be eligible.  •        Patients were not allowed to take part in the study if they had a history of chikungunya virus infection, immune-mediated or chronic arthritis or arthralgia, a known or suspected immune system defect, or if they had received an inactivated vaccine or a live vaccine in the two weeks before getting VLA1553 or any live attenuated vaccine 4 weeks before getting VLA1553. •        The main goal was to see how many people who were negative at the start had a protective level of chikungunya virus antibodies 28 days after vaccination, as measured by a 50% drop in plaques in a micro plaque reduction neutralization test (PRNT) with a PRNT50 titre of at least 150. •        After a single vaccine, VLA1553 caused chikungunya virus-neutralizing antibodies to be made in 263 (98.9%) of the 266 people in the VLA1553 group (95% CI: 96.7%–99.8%; p<0.0001), 28 days after the vaccine, regardless of age.  •        VLA1553 was usually safe, with side effects that were similar to those of other licensed vaccines, and both younger and older adults did well with it.  •        Serious side effects were seen in 46 (1.5%) of the 3082 people who were given VLA1553 and in 8 (0.8%) of the 1033 people who were given a placebo.   •        Only two major side effects were thought to be caused by treatment with VLA1553. One was a mild case of myalgia, and the other was a syndrome of inappropriate antidiuretic hormone secretion. Both people recovered completely. Author : Dr. Aditi Yadav