Merck & Co yesterday said it has sought clearance to market its shingles vaccines, Zostavax (zoster vaccine live), in the USA to prevent long-term nerve pain associated with the virus.

Shingles occurs when the virus that causes chickenpox reactivates after lying dormant in the body, typically after several decades, and can affect anyone who has had chickenpox. Approximately 25%-50% of patients older than 50 years of age develop chronic pain after shingles.

Merck says more than 90% of adults in the USA have had chicken pox and that up to half of all people living to age 85 will develop shingles during their lifetime. Zostavax is one of four vaccines the US giant has nearing the market and is one of the weapons in its turnaround strategy [[28/04/05d]] following the withdrawal of its billion-dollar painkiller Vioxx (rofecoxib) [[01/10/04a]].