GlaxoSmithKline PLC's blockbuster Shingrix vaccine has been approved by China's regulators, opening up even more potential for growth for the shingles prevention jab, which is already forecast to have sales significantly over £1 billion in 2019.

The approval follows an overhaul of China's National Medical Products Administration last year, in which the time to approval was accelerated. Shingrix, which is for adults aged 50 years or over, was included on a list of 48 "clinically urgently needed new medicines" designated for expedited review by the regulator. The vaccine will be introduced into China in 2020, Brentford, London-based GSK said in a statement.

GSK is looking to develop more vaccines for adults following the success of Shingrix, which was first approved in the U.S. in October 2017 and has now been given the green light in the European Union, Canada, Japan and Australia. Sales of the vaccine, which takes up to 9 months to produce, doubled to £357 million in the first quarter, but manufacturing capacity has been limited.

"Shingrix has delivered another fantastic performance in the quarter ... and we now expect annual sales to be significantly more than £1 billion in 2019," CEO Emma Walmsley recently told reporters on the company's first quarter conference call. While demand has outstripped supply in the U.S. market, Walmsley said GSK is investing in manufacturing capacity for Shingrix and other vaccines and announced $100 million of investments at a site in Hamilton on May 1. GSK said the introduction of Shingrix in China will be phased due to the need to ensure "consistent and reliable supply" in all countries.

Shingles is caused by the same varicella zoster virus that causes chickenpox and typically presents as a painful, itchy rash that develops on one side of the body and can last for up to four weeks.

"Today's approval of Shingrix in China is recognition of the significant scientific advance this vaccine represents," said Thomas Breuer, senior vice president and chief medical officer of GSK Vaccines. "We welcome the Chinese government's progress to enable faster entry of new products into China and we look forward to working with the relevant agencies to bring the benefits of this vaccine to local communities."