The U.S. Food and Drug Administration approved a pre-filled syringe version of GSK's blockbuster shingles vaccine Shingrix, providing patients a more convenient option to receive the shot, the company said on Thursday.

Shingles is a viral infection that causes a painful rash anywhere on the body and can sometimes lead to serious complications such as long-term nerve pain and vision loss.

The infection is caused by the varicella-zoster virus (VZV), a type of herpes virus that remains in patients' bodies after they have had chickenpox and reactivates years later.

The previous version of GSK's vaccine required a healthcare professional to mix the powdered form of the virus proteins with a liquid that boosts the immune response, before administration.

The new form of Shingrix, which does not require the mixing, was approved based on data that showed both versions were equally effective.