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Home » Varicella vaccine — 25 years of success against chickenpox

Varicella vaccine — 25 years of success against chickenpox

The varicella vaccine, which became available in 1995 in the USA, has had over 25 years of success in preventing chickenpox, a disease that, pre-vaccine, killed 145 children per year. In addition, herpes zoster, or shingles, cases have dropped because of the chickenpox and shingles vaccines.

All vaccines have their own stories of success, like how the smallpox vaccine eradicated smallpox across the world, but the chickenpox vaccine (and the related shingles vaccine) have done a spectacular job in reducing cases of chickenpox and shingles across the world since its introduction just over 25 years ago.

I have previously written about the success of the varicella vaccine in the USA, and this new peer-reviewed research describes the successes of the varicella vaccine. As I always do, I will analyze the paper and tell you what it says about the vaccine’s success.

Varicella Zoster Vaccine in a glass vial for Chickenpox

Chickenpox and the Varicella vaccine

Contrary to the claims made by many people, chickenpox is a severe disease with some dangerous complications. It is not merely a “nuisance.”

Chickenpox is an infection caused by the Varicella zoster virus (VZV). Although most cases are in children under age 15, it can attack older children and adults can get it. The virus spreads quickly from person to person. (To be clear, chickenpox is not even distantly related to monkeypox.)

The classic symptom of chickenpox is an uncomfortable, itchy rash. The rash turns into fluid-filled blisters and eventually into scabs. It usually shows up on the face, chest, and back and then spreads to the rest of the body.

Other symptoms include:

  • Fever
  • Headache
  • Tiredness
  • Loss of appetite

The disease usually lasts from 5-10 days.

Unfortunately, VZV stays in the body, usually in nerve roots along the spine, and, for unknown reasons, returns as a debilitating disease called shingles (or herpes zoster), which can be prevented with the shingles vaccine

Before the launch of the vaccine, according to the CDC, “an average of 4 million people got chickenpox, 10,500 to 13,000 were hospitalized, and 100 to 150 died each year.” And untold numbers which eventually developed shingles decades later.

The VARIVAX chickenpox vaccine was first licensed in Japan and the USA in 1995. In the USA, the CDC recommends the first dose at age 12 through 15 months and the second dose at age 4 through 6 years.

a mother caring for her sick child

New varicella vaccine research

In a public presentation on 23 February 2023 and in an article published on 21 October 2022 in the Journal of Infectious Diseases, Mona Marin, MD, Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, and colleagues reported the results of their analysis of chickenpox cases, hospitalizations, and deaths before and after the launch of the chickenpox vaccine in 1995.

Here are some key results:

  • Within 10 years of initiating vaccination with one dose of the varicella vaccine in 1995, the incidence of chickenpox cases, hospitalizations, and deaths declined by 71% to 91% compared to the years before the vaccine was available.
  • In 2007, the CDC recommended a two-dose schedule for the vaccine because there was still limited transmission of the disease. By 2019, cases decreased by over 97%, hospitalizations decreased by 94%, and deaths decreased by 97% compared to the years before the vaccine became available in 1995. I know this is supposed to be a fact-filled recitation of data, but those are impressive decreases.
  • Among individuals under the age of 20, the results were even more impressive — cases decreased by 99%, hospitalizations by 97%, and deaths by 99%.
  • Individuals over 50 years of age saw a 97% reduction in deaths from chickenpox.
  • During the period studied before the introduction of the vaccine (1990-1994), the annual mortality rate from chickenpox was 0.4-0.6 per million population per year.

Over the last 25 years, varicella vaccination resulted in 91 million cases of chickenpox prevented, 238,000 hospitalizations from chickenpox prevented, and 1,933-2,446 deaths chickenpox prevented. Although we do not have definitive data at this time there probably is also an impressive number of shingles cases that were prevented because these millions of kids and young adults avoided contracting the varicella virus which eventually leads to shingles.

Photo by Sincerely Media on Unsplash


When we say that vaccines, like the one for chickenpox, are safe and effective, and that it’s settled science, it is because we have overwhelming evidence such as what was presented by Marin et al. Today, we hardly hear of cases of chickenpox, which used to run rampant through schools before 1995. And not only was it a danger to children, it meant lost productivity and wages as parents stayed home with their kids.

I have a personal story about chickenpox that I might share here one day. I was one of the unlucky ones that had two serious side effects from the disease because the vaccine wasn’t available when I was a child.

Because the vaccine is available through the Vaccines for Children program, all US children are eligible to get the vaccine at no cost. This is the one area where the USA exceeds just about every other country in healthcare policy.

Vaccines save lives. And we have more evidence of that simple scientific fact.


Michael Simpson
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