Valneva and Pfizer have reported additional positive data from the Phase II VLA15-202 clinical trial of the VLA15 vaccine candidate for Lyme disease.

VLA15 is an experimental multivalent protein subunit vaccine that targets the outer surface protein A (OspA) of Borrelia.

The vaccine covers six serotypes prevalent in North America and Europe.

The randomised, observer-blind, placebo-controlled Phase II trial in the US assessed the immunogenicity and safety of the vaccine administered on a 0-2-6-month vaccination regimen.

It enrolled 246 healthy adults aged 18 to 65 years to receive either a 135µg or 180µg dose of VLA15 or a placebo.

An alum adjuvanted formulation of VLA15 was given intramuscularly in the trial.

As reported in October 2020, the trial met its primary goal, showing VLA15 was immunogenic across all tested dose cohorts.

The vaccine also induced greater antibody responses for all serotypes at one month following the primary vaccine regimen.

According to the continued analysis conducted at month 18, antibody titers waned thereafter across all cohorts, even though the levels were noted to be above baseline.

This data indicates the requirement for the booster vaccine, Pfizer noted.

The vaccine was found to be safe and well-tolerated across all doses and age groups analysed in the trial without any serious adverse events reported.

Participants completing the primary immunisation series with 180µg doses of the vaccine were randomised to receive another 180µg dose of VLA15 or placebo at month 18.

VLA15’s acceptable safety profile was confirmed through one month of receiving the booster.

A booster shot administration stimulated a robust anamnestic response yielding a 2.9 to 4.2-fold growth in anti-OspA IgG antibody titers versus those reported after the primary series.

All subjects seroconverted to anti-OspA IgG on receiving the booster, indicating complete seroconversion rates for all OspA serotypes.

Valneva chief medical officer Juan Carlos Jaramillo said: “Lyme disease represents a high unmet medical need, which impacts the lives of millions of people in the Northern Hemisphere.

“We are excited by these additional Phase II results, which we believe take us a step closer to making a major contribution against this severe disease, subject to regulatory approval.”

In April 2020, Valneva partnered with Pfizer to develop and market the VLA15 vaccine.

The two companies are currently working together to advance the vaccine development and intend to commence a Phase III trial next year.