Tick-Borne Encephalitis Vaccine Gets Priority Review

2006 Dr. Amanda Loftis, Dr. William Nicholson, Dr. Will Reeves, Dr. Chris Paddock This photograph depicted a dorsal view of a female “lone star tick”, Amblyomma americanum. An Ixodes or “hard” tick, A. americanum is found through the southeast and south-central states, and has been shown to transmit the spirochete, Borrelia lonestari, the pathogen responsible for causing a Lyme disease-like rash known as “Southern tick-associated rash illness” (STARI). Representatives from all three of its life stages aggressively bite people in the southern U.S. Research indicates that live spirochetes are observed in only 1-3% of specimens. Note the characteristic “lone star” marking located centrally on its dorsal surface, at the distal tip of its scutum. Symptoms and Diagnosis:

Persons living or traveling in southeast or southcentral states who develop a red, expanding rash with central clearing (the rash of Lyme disease, erythema migrans) following the bite of the lone star tick, A. americanum, should see their physician. The Centers for Disease Control and Prevention is interested in obtaining samples from such patients under an Institutional Review Board-approved investigational protocol.

Prevention and Treatment:

Prevention measures similar to those for the Lyme disease vector will reduce your exposure to infected ticks. See Lyme Disease Prevention and Control for information on how to:

– avoid tick habitats,

– reduce tick abundance,

– use personal protection equipment, and

– check and remove ticks.

TicoVac is an inactivated whole virus vaccine developed using a master ‘seed’ virus that is similar to the tick-borne encephalitis virus found in nature.

The Food and Drug Administration (FDA) has accepted for Priority Review the Biologics License Application (BLA) for TicoVac (Pfizer), an investigational vaccine for active immunization to prevent tick-borne encephalitis in individuals 1 year of age and older.

TicoVac is an inactivated whole virus vaccine developed using a master ‘seed’ virus that is similar to the tick-borne encephalitis virus found in nature. Tick-borne encephalitis is a viral infection of the brain and spine that is transmitted through the bite of an infected tick. 

The BLA is based on data from clinical trials that assessed the safety and immunogenicity of the vaccine across 2 age groups (1-15 years of age and 16-65 years of age). Results from these trials showed that after 3 doses of the vaccine, the pooled seropositivity rates were 99-100% in individuals 1-15 years old and 94-99% in those 16 years of age and older. As for safety, the vaccine was found to be well tolerated with no unexpected adverse events or vaccine-related serious adverse events observed.

Additionally, subsequent real-world studies showed that the vaccine was 96-99% effective in individuals treated with at least 2 doses, and provided long-lasting immune memory following 2 to 3 doses. 

“We are proud that today’s US FDA Priority Review acceptance acknowledges the potential value that our vaccine candidate can bring,” said Nanette Cocero, PhD, Global President, Vaccines, Pfizer Inc. “If approved in the US, we hope this vaccine will help protect those traveling to or residing temporarily in at-risk locations, potentially including military personnel who are serving overseas.”

A Prescription Drug User Fee Act (PDUFA) target date of August 2021 is expected for the application.


US FDA accepts for Priority Review Pfizer’s application for TicoVac™ (tick-borne encephalitis vaccine). [press release]. New York, NY: Pfizer, Inc.; February 23, 2021. 

This article originally appeared on MPR