Shingles is a viral infection that manifests as a painful rash, caused by the varicella-zoster virus (VZV). This is the same virus responsible for chickenpox, and after a chickenpox infection resolves, VZV remains dormant in nerve cells. The virus can reactivate later in life, particularly as the immune system weakens with age, leading to shingles.
This reactivation can result in significant pain, often described as burning or shooting, accompanied by a blistering rash. Shingles can lead to complications such as postherpetic neuralgia (PHN), where nerve pain persists for months or years. Other complications can include vision loss or, rarely, brain inflammation. Vaccination is important for prevention.
The First Shingles Vaccine
The first vaccine specifically developed to prevent shingles, Zostavax, was approved by the U.S. Food and Drug Administration (FDA) on May 25, 2006. Manufactured by Merck & Co., Inc., Zostavax was a live, attenuated virus vaccine. It contained a weakened form of the varicella-zoster virus to stimulate an immune response without causing disease.
Initially, Zostavax was approved for individuals 60 and older. In March 2011, the FDA expanded approval to include those aged 50 to 59. The vaccine aimed to reduce the risk of shingles and postherpetic neuralgia.
Zostavax was administered as a single injection under the skin. However, Zostavax was discontinued in the United States as of November 18, 2020.
The Development of a Newer Vaccine
Following Zostavax, a newer shingles vaccine called Shingrix was developed and approved by the U.S. Food and Drug Administration on October 20, 2017. Manufactured by GlaxoSmithKline, Shingrix is a recombinant subunit vaccine, meaning it does not contain a live virus.
It uses a specific protein from the varicella-zoster virus combined with an adjuvant. This adjuvant enhances the body’s immune response, leading to a stronger and more targeted defense against the virus. Shingrix aimed to provide improved efficacy and broader applicability for shingles prevention, offering robust protection.
Key Distinctions Between the Vaccines
The two shingles vaccines, Zostavax and Shingrix, differ significantly in their composition, efficacy, and administration. Zostavax was a live, attenuated vaccine containing a weakened form of the virus. Shingrix is a recombinant subunit vaccine that uses a viral protein combined with an adjuvant.
Clinical trials demonstrated Shingrix to be substantially more effective, with over 90% efficacy in preventing shingles across various age groups, including adults aged 50 and older. In contrast, Zostavax had an overall efficacy of about 51% in adults over 60, with its effectiveness decreasing further in older age groups.
Zostavax was given as a single injection under the skin. Shingrix requires a two-dose series administered into the muscle, with the second dose typically given between two and six months after the first.
Protection from Zostavax waned significantly after approximately five years. Shingrix has demonstrated high levels of immunity for at least seven years, with some data suggesting protection can last longer. Unlike Zostavax, Shingrix is suitable for individuals with weakened immune systems.
Current Vaccination Guidance
Current recommendations for shingles vaccination focus on Shingrix. The Centers for Disease Control and Prevention (CDC) recommends two doses of Shingrix for healthy adults aged 50 and older. The second dose should be administered between two and six months after the first.
Shingrix is also recommended for adults aged 19 and older who are immunodeficient or immunosuppressed due to disease or therapy. Individuals who previously received Zostavax are advised to get vaccinated with Shingrix to enhance their protection.
The CDC suggests Shingrix can be given as early as eight weeks after a Zostavax vaccination. It is not necessary to verify a history of chickenpox or prior shingles infection before receiving Shingrix. Shingrix is considered the preferred option for preventing shingles and its associated complications.