As a result of the high demand for GlaxoSmithKline's new shingles vaccine, Shingrix, two U.S. senators have urged the pharma giant to boost inventory levels on facing a shortage in the supplies even after the company established their "fair and equitable" process to ship Shingrix doses.

In a letter to GSK’s CEO Emma Walmsley, Senators Amy Klobuchar, D-Minn., and Tina Smith, D-Minn., asking her to look at "what more GSK can do to end the shortage as quickly as possible," and stated that is there seem to be no "contingency plans" to ensuring a sufficient supply for the launch of the vaccine. 

According to senators, patients may not be able to complete the recommended schedule of two doses in six months due to the lack of the vaccine.

GlaxoSmithKline’s Shingrix is seen as a better alternative to Merck's Zostavax, a possible reason for the escalation in its demand. It won approval last fall and days later, CDC vaccine advisers recommended the vaccine above the latter.

A GSK representative remarked that as of May, more than 1.5 million people had received the vaccine and that vaccinations against shingles appeared to be "at a rate many times that of prior years." 

To tackle this increasing need and to ensure patients are able to complete the series, GSK devised a "fair and equitable allocation plan across all customer segments". Until their inventory levels have recovered, the company has implemented order limits as well as delayed "broad consumer education activities" such as TV ads.

Commercially, Shingrix has exceeded expectations even though GSK struggles to keep up with the high demand.  The vaccine generated sales of $150 million in the first quarter, leading experts to estimate revenue of $600 million this year.