China’s drug regulatory authority, National Medical Product Administration (NMPA), has approved GlaxoSmithKline’s new vaccine for herpes zoster (shingles) in adults 50 years old or older, opening up a third major market for the runaway vaccine success.

The Chinese approval followed NMPA’s decision last summer to invite manufacturers of key drugs to submit applications on the basis of foreign data.

In the US, Shingrix has enjoyed rapid growth since its approval by the Food and Drug Administration (FDA) in October 2017.  At the end of the first quarter 2019, sales was 43% ahead of analysts’ expectations, reports said.

US sales surged after the Centers for Disease Control and Prevention (CDC) recommended Shingrix over Merck & Co’s older vaccine Zostavax in older populations.

US sales could have been higher, had GSK not faced supply problems. The vaccine was approved by the European Medicines Agency (EMA) last spring, but has not been extensively available in part due to a global shortage.

In China, some three million adults are said to be affected each year by shingles – a painful condition that can affect anyone who has already had chicken pox. The Chinese market for the vaccine is about three times the size of the US market, according to the CDC.

To avoid exacerbating the shortage, GSK said it plans to introduce Shingrix in China in stages, starting in 2020. Globally, the UK’s largest drugmaker said it is investing in “significant” capacity expansion. In April this year, it said it was investing $100 million to upgrade an existing site in Montana, USA, that would add adjuvant production capabilities.

Despite the apparently bright future for the now leading shingles vaccine, there are concerns about the adjuvant, which potentially could lead to problems down the road. According to pharmaceutical journals, instead of the commonly used aluminum-containing adjuvants, Shingrix uses an adjuvant formulation that contains an extract from the soapbark tree.

Since its launch, the vaccine has seen incidents of hypersensitivity immune system disorders. The FDA at GSK’s request has now added the information to the drug’s label. Chinese authorities has have asked the company to run post-approval studies to update the vaccine’s China-specific data, to understand whether the novel adjuvant could lead to higher risk of immune disorders.