NATIONAL (WEHT) – Pfizer has begun a study on its COVID-19 vaccine that’s been tweaked to target the Omicron variant. 

The trial includes more than 14 hundred adults, ages 18 to 55. The study will look at the shot’s safety and efficacy of both a booster and a first dose and compare it to the original vaccine. While Omicron is more likely to cause break through cases, it’s not yet clear that a change to the shot is needed.

There’s no timetable for the trial, but last month, Pfizer’s CEO said they will have an Omicron vaccine by March.