Varicella zoster vaccine (recombinant)

Recombinant zoster vaccine, manufactured as the product Shingrix by GlaxoSmithKline, is an adjuvanted non-live recombinant vaccine indicated for prevention of shingles. First approved in October 2017 by the Food and Drug Administration, Shingrix is the preferred vaccine for preventing varicella zoster infection in people aged 50 years and older, replacing Zostavax as first line therapy.

Herpes zoster, also known as shingles, is caused by a reactivation of Varicella Zoster Virus (VZV), the virus that commonly causes Chickenpox in childhood. Following initial infection of VZV and resolution of Chickenpox as a child, VZV then lies dormant within the dorsal root ganglion of the central nervous sytem. Decades later, when the body's immune system weakens with age, VZV is able to reactivate and descend through the nerve cells to the surface of the skin where it causes a painful blistering rash. Risk factors for developing shingles include old age, with rates increasing substantially in person's over the age of 50, low immune function or immunosuppression, psychological stress, and diabetes. Person's living with HIV or cancer, those taking immunosuppressants, and transplant recipients are particularly at risk .

One of the most common complications associated with shingles is the development of Post-Herpetic Neuralgia (PHN), a persistant severe nerve pain that develops as a result of chronic pain from shingles lesions. PHN can last for days, months, or even years following resolution of shingles. Other complications also include bacterial infection, spread of the shingles rash to the eye (herpes zoster ophthalmicus) or ear, nerve palsies, or spread of VZV to non-immune persons via contact with varicella lesions.

There are numerous advantages to using Shingrix over Zostavax. Clinical trials for Shingrix have shown greater than 90% efficacy in adults aged 50 and older, with 89% efficacy in preventing postherpetic neuralgia in patients 70 years and older and 91% efficacy in patients 50-70 years of age . This is a significant improvement over its predecessor, Zostavax, which reduces the risk of shingles by only 51% and the risk of post-herpetic neuralgia by 67% . Efficacy of Zostavax also wanes over time, with protection against shingles and PHN lasting only around 5 years. Furthermore, because Shingrix is an inactivated vaccine it can also be used to prevent shingles and PHN in individuals with suppressed immune systems, who are already at increased risk of developing shingles, while Zostavax, a live attenuated vaccine, is contraindicated.

The main immunological component of Shingrix vaccine is glycoprotein E (gE), a protein found on the surface of varicella zoster virus (VZV). Immune exposure to gE protein stimulates the development of anti-gE antibodies, and therefore adaptive immunity to VZV. Shingrix also contains an adjuvant system, AS01B, which is intended to enhance the immunological response to the vaccine leading to longer lasting and greater immunogenicity to the herpes zoster virus .