Chicken Pox and Shingles

Chicken Pox and Shingles

 

     In the pre-vaccine era, nearly all cases in the U.S. occurred in 3-6 year olds, and they developed permanent immunity. Before adults reached twenty years of age, 90% were immune. Infants were also protected by maternal antibodies. Today, adolescents (9-11 years old) are acquiring chicken pox which was highly unusual in the pre-vaccination era.  The rate of Shingles and Chicken Pox in adulthood is also increasing, and eventually the burden may shift and rise to infants.

 

 

 

    

     The Varicella vaccine is estimated to be 70% effective for up to 10 years, or as little as 5 years, after vaccination. 5% of vaccine recipients would go on to get a mild case of chicken pox within a year after the inoculation. The Varicella vaccine was first recommended as one dose given at one year of age.  Now, due to the lack of efficacy, and rapidly waning immunity, a second dose was recommended for 4-6 year olds.

 

 

 

 

     A 2007 study in the New England Journal of Medicine found that a single shot does not produce a sufficient immune response in approximately 20% of people who receive it. Therefore, it is hoped that a two-shot regimen will create a larger population of fully immunized people and should reduce breakthrough disease. Health officials admit they don’t now how long a second dose will provide immunity.

   

     As the Varicella vaccine became recommended and mandated for school attendance, natural circulation and ‘boosting’ of the virus became less. This not only put those who have acquired natural immunity at risk, but the vaccine recipients as well. Why? The vaccine does not allow the wild-type virus to circulate and boost protection for everyone, especially the older populations. This is why Japan never mandated the Varicella vaccine but left it as a ‘choice’ vaccine. Natural boosts, or exposures, from children also help keep Shingles from occurring. The effectiveness of the chicken pox vaccine is dependent upon natural boosting. As the chicken pox declines, so will the effectiveness of the vaccine.  Dr. James Cherry had this to say:

 

          “Our immunity is stimulated by being exposed to the Chicken Pox. When that stimulation goes away, our protection is going to decrease. So we’ll see more cases of Shingles. My guess is that we’re going to be giving doses of the [varicella] vaccine to 30 and 40 year olds to prevent Shingles. The better we do, [eradicating chickenpox], the more we’re going to see Shingles.”

 

 

     The adult Shingles rate increased by 90% from 1998-2003. A Shingles vaccine, Zostavax, was made, and its only purpose is to try and prevent Shingles cases in older susceptible adults.  The efficacy is only 41% for those aged 70-79 years, and an 18% efficacy for 80 years and older. The duration of protection is not yet known. Gary S. Goldman’s research shows that Shingles results in 3 times as many deaths and 5 times the number of hospitalizations.

 

     In the pre-vaccine era, serious problems or complications were rare. Parents and doctors knew exposing their children in early childhood reduced complication rates.  The highest complication rates or death have always been in very young infants, teens, adults, and those with compromised immune systems.  The United States is the only country that routinely vaccinates against Chicken Pox. It should also be noted that in 1981, chicken pox was removed as a nationally notifiable disease. Yet, the Varicella vaccine was licensed and recommended in 1995 with only 14 states reporting cases to the CDC. In 1998/99, only Varicella deaths were to be reported. In 2002, CSTE recommended Varicella once again be added as a nationally notifiable disease by the year 2003, with all states included by 2005.

 

 

     How many times have you heard that the Varicella vaccine would give a ‘milder’ infection? That the ‘milder’ infection is a good thing? Is a milder infection really a good thing? What about ‘recurrent’ cases or ‘breakthrough cases?  A milder infection can simply suppress the virus and eventually lead to a more serious infection or a chronic illness later on when reintroduced.

 

        Immunity acquired through natural infection still forms much of the population’s immune defense. The level of a population’s immunity to a disease depends upon both the proportion artificially immunized and the frequency of contact with the infectious organism (wild or attenuated). When exposure to the antigen becomes uncommon, there is no stimulus to maintain antibody levels, and susceptibility increases. If the organism causing a disease is then reintroduced while immunity is low it is likely to spread quickly and cause severe illness. A constant endemic level of a disease may cause less overall morbidity, mortality and disruption than periodic epidemics. Islands and other isolated areas demonstrate this principle. Their populations may not be exposed to a certain infectious disease for decades. If the organism is then reintroduced, the low immunity levels among these people permit the infection to spread rapidly throughout the entire population. Severe illness and a high case fatality rate usually result.”

 

   If natural infections are not allowed to boost the antibody titers from time to time, children could very well end up susceptible adults, and at a time when Chicken Pox can be more serious, and heightened secondary infections can result.

 

 

      Some children with histories of having acquired natural Varicella went on to experience Shingles, and the rate is approaching those of adults. Based on a study in the New England Journal of Medicine, 9.5% of children have breakthrough disease. Children 8-12 years who were vaccinated 5 years previously had a higher incidence of moderate to severe disease.  A study by Seward et al., indicated that 13% of Varicella cases diagnosed by pediatricians are recurrent.

 

 

 

 

     In the pre-vaccine era, when a child came down with an active chickenpox case, they were kept home for up to 2 weeks until the pox scabbed over. Any child who was known to have been exposed to a known case of Chicken Pox was also watched closely for the beginning of symptoms, and kept away from other susceptible people if needed.  If you have read the package insert for the Varicella vaccine, it warns that newly vaccinated persons could transmit the virus for up to 6 weeks, and to avoid associations with susceptible high risk persons. How many people do you know keep their newly vaccinated child out of daycare or school for 6 weeks? The issue of virus transmission after the vaccine is not generally discussed.

 

 

     The rate of Chicken Pox may indeed be lower in children today since the introduction of the vaccine, but at what cost and to whom? We have shifted a once normal and self-limiting childhood disease into an adult disease, and possibly down the road, an infant disease, when it can be much more serious. When you consider what is yet not ‘known’, the outcome is anyone’s guess.

 

 

 

 

 

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