Feb 28, 2024 ACIP Meeting - Chikungunya Vaccines

The session begins with an introduction by Dr. Wilbur Chen, the work group chair, for the Chikungunya vaccine presentation. He discusses the licensing of the Chikungunya vaccine by Valneva in November 2023, the first of its kind globally. The session's agenda includes reviewing the vaccine's policy options for use among US travelers, laboratory workers, and pregnant or breastfeeding individuals. Dr. Chen also highlights the work group's previous presentations to the ACIP and introduces the next speaker, Dr. Susan Hills, who will provide an update on the licensure of the Chikungunya vaccine.

Dr. Susan Hills provides an update on the licensure of the live attenuated Chikungunya vaccine, known as lxchiq, approved by the FDA in November of the previous year. The vaccine is licensed for individuals at increased risk of exposure to Chikungunya virus, with specific contraindications. She discusses the warnings and precautions related to the vaccine, including the potential for Chikungunya-like adverse reactions and the lack of data on vertical transmission risks. Dr. Hills also mentions the accelerated approval pathway used for the vaccine and the post-marketing studies required by the FDA to confirm clinical benefits.

The presentation continues with a discussion on the proposed policy options for the use of Chikungunya vaccine among adult travelers and laboratory workers. Dr. Hills provides a detailed overview of Chikungunya virus transmission, its symptoms, and the risk factors for severe disease. She reviews the immunogenicity and safety data from the vaccine's clinical trials and discusses the work group's draft recommendations for its use. The recommendations include vaccination for travelers to areas with Chikungunya outbreaks and consideration for those traveling to areas with a history of transmission. Dr. Hills emphasizes the importance of shared clinical decision-making for certain individuals.

Dr. Hills elaborates on the rationale behind the proposed recommendations for Chikungunya vaccine use, focusing on the evidence of virus transmission within the last five years as a criterion. She clarifies the definition of an outbreak for the recommendations and discusses the importance of moderate exposure to mosquitoes for travelers. Dr. Hills also addresses the concerns regarding the upper age limit for vaccination and provides data on adverse events in vaccinated subjects. The discussion includes the challenges of tracking accurate information on Chikungunya transmission and the potential implications for vaccine recommendations.

The presentation concludes with a motion to approve the draft recommendations for the use of the Chikungunya vaccine. Dr. Daley proposes the motion, and Dr. Long seconds it. The discussion includes clarifications on the recommendations' language, the need for additional discussions with healthcare providers, and considerations for special populations such as immunocompromised individuals. Dr. Kotton raises concerns about the upper age limit for vaccination, and Dr. Hills addresses these concerns with data from clinical trials. The session proceeds with a discussion on the vaccine's use in laboratory workers, with Dr. Hills providing an overview of Chikungunya among this population.

Dr. Hills presents the proposed policy options for Chikungunya vaccine use among US laboratory workers, who are at potential risk of exposure to the Chikungunya virus in their work. She reviews the reported cases of Chikungunya infection in laboratory workers globally and in the US, emphasizing the importance of vaccination for this specific group. Dr. Hills discusses the draft recommendation, which advises vaccination for laboratory workers with potential exposure to Chikungunya virus. The recommendation is based on the benefits outweighing the risks for this small group of laboratorians working with live virus. The session concludes with a question and answer segment, where Dr. Hills addresses queries about vaccine counseling for laboratorians.

Dr. Hills discusses the proposed clinical guidance for the use of the live attenuated Chikungunya vaccine in pregnant and breastfeeding individuals. She provides background information on Chikungunya disease during pregnancy and the potential risks and benefits of vaccination. Dr. Hills outlines the objectives of vaccination during pregnancy, which include protecting the pregnant person and potentially the infant through transplacental transfer of antibodies. She presents the work group's proposed guidance, which advises avoiding vaccination during the first trimester and after 36 weeks gestation due to potential concerns associated with vaccine viremia. Dr. Hills also addresses the lack of data on the vaccine's safety during pregnancy and the plans for additional studies. The session includes input from ACOG representatives and other experts, emphasizing the importance of shared clinical decision-making and the potential benefits of vaccination in high-risk situations.