How Long Is The Chicken Pox Vaccine Good For?

Chickenpox, also known as varicella, is a highly contagious viral infection that causes an itchy rash with small, fluid-filled blisters. Before the introduction of the chickenpox vaccine in 1995, virtually every child contracted chickenpox by adolescence. While usually mild in healthy children, chickenpox can result in complications like bacterial skin infections, pneumonia, brain inflammation, and hemorrhage in some cases. The chickenpox virus also stays dormant in the body and can reactivate later in life as shingles, leading to a painful rash.

To prevent chickenpox and its potential complications, the U.S. Centers for Disease Control and Prevention (CDC) recommends routine chickenpox vaccination. The CDC vaccination schedule calls for children to receive two doses – the first between 12-15 months old and the second between ages 4-6. For adolescents and adults aged 13 and older who’ve never had chickenpox or the vaccine, the CDC advises receiving two catch-up doses at least 28 days apart.

But how long does the immunity induced by the chickenpox vaccine last? Keep reading to learn more about the duration of vaccine protection and who may need additional doses down the line.

How The Chickenpox Vaccine Works

There are two chickenpox vaccines licensed for use in the U.S. – Varivax and ProQuad. Both are live attenuated vaccines, meaning they contain weakened forms of the live chickenpox virus This prompts the immune system to generate antibodies against the virus without actually causing infection

The Varivax vaccine only protects against chickenpox, but the ProQuad vaccine also protects against measles, mumps, rubella, and chickenpox (also known as MMRV). Following two doses, more than 90% of people who get both vaccines are immune to them.

Lifelong Immunity For Most People

Multiple long-term studies have shown the chickenpox vaccine provides long-lasting immunity for the vast majority of people who receive the recommended two-dose series.

In a 14-year study of over 7,500 children aged 12-23 months immunized with Varivax, incidence of breakthrough chickenpox was nearly 90% lower compared to unvaccinated kids. Effectiveness remained stable over the entire study period, demonstrating sustained immunity.

In a different study, over 450 kids were tracked for 15 years after their second vaccination. At the conclusion of the study period, 99% of the patients still had detectable antibody levels and none of them had developed breakthrough infections.

Based on such evidence, the CDC states most vaccinated people will be protected for life after two doses. The vaccine confers better immunity than natural infection, so even if you had chickenpox previously, vaccination further boosts your protection.

Possible Need For Booster Doses

Most healthy people only need two shots to be immune for life, but immunity can wear off faster in some groups. At this time, the CDC doesn’t think anyone should get booster shots on a regular basis. However, they say that some people may need an extra dose in the following situations:

• Immunocompromised children: Those with HIV, leukemia, lymphoma, generalized malignancy, or receiving immunosuppressive therapy should get a third vaccine dose 6-12 months after the second.

• Healthcare workers: Those vaccinated as children but with negative antibody levels upon testing should receive two catch-up doses at least 4 weeks apart.

• Pregnant women: Pregnant women without evidence of immunity should get vaccinated postpartum before hospital discharge.

• Outbreak control: Additional doses may be recommended during chickenpox outbreaks.

For people vaccinated before age 13 who are not in any of the above categories, periodic antibody testing and boosters are not routinely recommended. But you should consult your doctor if concerned about waning immunity.

Monitoring Immunity Over Time

To assess if vaccine-induced immunity remains strong or starts decreasing with time, scientists periodically measure chickenpox antibody levels in vaccinated populations.

Several studies have looked at the difference between the amount of antibodies in kids right after their second vaccine and levels 5–20 years later. Even though some loss of effectiveness is normal over time, antibodies stay at levels that protect most kids for at least 15 to 20 years after they are vaccinated.

Research also suggests antibodies may fall faster in vaccinated adults. A study found antibody concentrations decreased by about 21-27% annually in adults, compared to only 2.5% in children. But even though antibodies decline faster in adults, levels still remain above proposed protective thresholds for at least 10 years post-vaccination.

While these studies are reassuring, experts continue monitoring antibody concentrations as time since vaccination increases. This data helps determine if and when boosters may be needed to maintain immunity.

The Bottom Line

Multiple studies confirm the vaccine provides durable immunity lasting at least 20 years in children vaccinated at the recommended ages. Immunity likely persists much longer than that – possibly a lifetime after the two-dose series.

Adults may need boosters sooner than children due to somewhat faster waning immunity. But protection still lasts for at least 10 years in most vaccinated adults.

The small number of people who do experience breakthrough chickenpox despite vaccination typically have milder symptoms with fewer lesions. Two doses reduce the risk of developing shingles later in life as well.

In the future, we may learn select groups like the elderly and immunocompromised could benefit from booster shots to maintain protection. But for now, the CDC does not advise routine boosters. Speak to your doctor if concerned your immunity may have decreased over time. With widespread chickenpox vaccination, we’ve seen dramatic drops in chickenpox cases and related complications.