Pfizer plans to study a third shot for its Covid-19 vaccine in the youngest kids, pushing back its timeline farther

American children under the age of five may not be vaccinated until mid-2022, as Pfizer said Friday that it’s going to now test a third dose of its Covid-19 vaccine in the trial.

The decision comes as Pfizer announced non-inferiority was not met for children between the ages of two and five when compared to older teenagers in the current trial.