Shingrix is a recombinant zoster vaccine that prevents shingles, also known as herpes zoster. It protects adults from the painful rash and complications associated with shingles, a condition caused by the reactivation of the varicella-zoster virus, the same virus that causes chickenpox. Shingrix is recommended for adults aged 50 and older, and for adults 19 and older with weakened immune systems.
Why a Second Dose is Critical
The Shingrix vaccination regimen involves two doses, typically administered intramuscularly between two and six months apart. The first dose primes the immune system, introducing it to a component of the varicella-zoster virus and initiating an immune response.
The second dose acts as a booster, significantly enhancing and prolonging the immune response generated by the first shot. Clinical trials demonstrated that the full protective efficacy of Shingrix is achieved only after receiving both doses. For adults aged 50 and older, two doses of Shingrix are over 90% effective in preventing shingles.
Impact of Incomplete Vaccination
Missing the second Shingrix shot means protection against shingles will be significantly lower and shorter-lived compared to completing the full two-dose series. While the first dose provides initial immune system priming, it is not sufficient to establish the lasting defense the vaccine offers. Studies indicate that after only one dose, effectiveness is reduced to about 69.5% in adults over 70, compared to over 90% with two doses.
Individuals who receive only one dose remain at a higher risk of developing shingles or its complication, postherpetic neuralgia (PHN), than those who complete the vaccination course. PHN involves chronic nerve pain that can persist for months or years after the shingles rash heals, affecting 10% to 18% of shingles patients. Without the second dose, the body’s immune response may not be strong enough to combat the varicella-zoster virus, leaving individuals more vulnerable to the disease.
Steps to Take After a Missed Dose
If you have missed your second Shingrix dose, contact your healthcare provider as soon as possible. The Centers for Disease Control and Prevention (CDC) advises the second dose can still be administered even if the recommended 2 to 6-month window has passed. You do not need to restart the entire vaccination series, regardless of how much time has elapsed since your first shot.
Receiving the delayed second dose is significantly better than not completing the series, as your immune system can still recognize and respond to it. Completing the vaccination course is important for achieving optimal and long-lasting protection against shingles and its complications. Your healthcare provider can help reschedule your appointment and ensure you receive the full benefits of the vaccine.