A phase 3 trial funded by Valneva and Pfizer shows that a four-dose series of the LB6V Lyme disease vaccine is safe and well tolerated in children and adolescents aged 5 to 17 years. In the 3,547-participant study across 57 United States sites, adverse events were mostly mild to moderate, with serious events matching placebo rates at 1.6%. LB6V targets six serotypes of the Borrelia burgdorferi OspA protein, neutralizing bacteria inside feeding ticks.
Phase 3 trial safety findings
- ▪Fever and injection site redness occurred more frequently in children aged 5 to 11 than in adolescents aged 12 to 17 during the LB6V Lyme disease vaccine trial.
- ▪The most common adverse events from the LB6V Lyme disease vaccine in pediatric participants were injection site pain, redness, fatigue, and headache, with the majority being mild to moderate.
- ▪In the phase 3 pediatric trial, 11.5% of LB6V Lyme disease vaccine recipients and 10.3% of placebo recipients experienced adverse events, with serious adverse events in 1.6% of each group.
- ▪Withdrawals due to adverse events in the phase 3 LB6V Lyme disease vaccine trial occurred in 0.8% of participants aged 5 to 11 and 0.6% of participants aged 12 to 17.
Phase 3 trial enrollment and participation
- ▪A phase 3 trial evaluated a four-dose series of the investigational LB6V Lyme disease vaccine in 3,547 healthy participants aged 5 to 17 across 57 United States sites between December 2022 and July 2025.
- ▪In the phase 3 pediatric trial, 1,207 vaccinated children aged 5 to 11 and 997 vaccinated adolescents aged 12 to 17 completed the four-dose LB6V vaccine series.
- ▪The phase 3 LB6V Lyme disease vaccine trial enrolled 1,907 children aged 5 to 11 and 1,640 adolescents aged 12 to 17, with an average recipient age of 11 years.
Pediatric trial backing and presentation
- ▪The phase 3 pediatric trial of the LB6V Lyme disease vaccine was funded and developed by pharmaceutical companies Valneva and Pfizer.
- ▪Results from the phase 3 LB6V Lyme disease vaccine trial were presented in a poster at the American Academy of Pediatrics 2026 National Conference in San Diego.
Mechanism of the LB6V vaccine
- ▪The LB6V Lyme disease vaccine contains six serotypes of outer surface protein A, whereas the earlier LYMErix vaccine contained only one serotype.
- ▪The LB6V Lyme disease vaccine induces human antibodies against outer surface protein A, neutralizing Borrelia burgdorferi bacteria inside a feeding tick before transmission.
History of the LYMErix vaccine
- ▪The Advisory Committee on Immunization Practices gave LYMErix a soft recommendation, excluding the vaccine from National Vaccine Injury Compensation Program coverage prior to its 2002 withdrawal.
- ▪The original Lyme disease vaccine, LYMErix, was approved in 1998 but voluntarily pulled from the United States market in 2002 due to low sales and litigation threats.
Debatable claims
- ▪ACIP should issue a routine recommendation for the LB6V Lyme vaccine upon FDA approval
- ▪Phase 3 trial results are sufficient to establish the safety of LB6V in children
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