In the almost 20 years since the FDA controversially approved Merck's ($MRK) chickenpox vaccine, the product--as well as similar combination shots--has faced multiple shortages. GlaxoSmithKline ($GSK) has also struggled to maintain supply of its rival vaccines and this week warned of yet another shortage.
The latest shortage can be traced back to GSK's production plant in Wavre, Belgium. GSK has stopped worldwide deliveries of two vaccines manufactured at the facility after discovering quality problems with some batches. The two affected vaccines both contain a chickenpox component, with Varilrix just protecting against the common childhood illness and Priorix-Tetra also covering measles, mumps and rubella (MMR).
News of the quality failing first emerged from Germany, where doctors are being recommended to ration use of both vaccines. Subsequent reporting by Reuters revealed GSK is stopping worldwide deliveries. "We're committed to resolve this supply disruption situation as soon as possible and are actively involved in keeping regulatory authorities and customers informed as we look to minimize the impact of this temporary supply disruption," a U.K. spokesperson for GSK told the news agency.
Reallocation of 2014 stock could help lessen the supply shortage, but GSK's first-quarter results are still expected to be affected by the issue. Merck is theoretically well positioned to capitalize, with its Varivax and ProQuad vaccines providing protection against chickenpox alone and in combination with MMR. Both Merck vaccines have also faced supply constraints, notably in 2001 and 2007.
Merck's shingles vaccine Zostavax, which like the chickenpox vaccines uses a varicella component, was also in short supply for years. FDA approval of a second plant for production of bulk varicella in September went some way to improving the reliability of supply, but the United Kingdom still suffered a shortage late in 2013. GSK has faced problems too, with strong demand in New Zealand leading to a shortage of Varilrix last May.