CHICKEN POX VACCINE

[Book  INJECTION! ] How Gary Goldman blew the whistle about the problems witht the chickenpox vaccine

http://www.cdc.gov/epo/mmwr/preview/mmwrhtml/rr4806a1.htm

Morbidity Mortality Weekly Report
May 28, 1999 / 48(RR06);1-5
Prevention of Varicella Updated Recommendations of
the Advisory Committee on Immunization Practices
(ACIP)


ADVERSE REACTIONS

Reporting of Postlicensure Adverse Events

       Data on potential adverse events are available from the Vaccine Adverse Event Reporting System (VAERS). During March 1995-July 1998, a total of 9.7 million doses of varicella vaccine were distributed in the United States. During this time, VAERS received 6,580 reports of adverse events, 4% of them serious. Approximately two thirds of the reports were for children aged less than 10 years. The most frequently reported adverse event was rash (rate: 37/100,000 vaccine doses distributed). Polymerase chain reaction (PCR) analysis confirmed that most rash events occurring within 2 weeks of vaccination were caused by wild-type virus (Merck and Company, Inc., unpublished data, 1998). Postlicensure VAERS and vaccine manufacturer reports of serious adverse events, without regard to causality, have included encephalitis, ataxia, erythema multiforme, Stevens-Johnson syndrome, pneumonia, thrombocytopenia, seizures, neuropathy, and herpes zoster (CDC, unpublished data, 1998). For serious adverse events for which background incidence data are known, VAERS reporting rates are lower than the rates expected after natural varicella or the background rates of disease in the community (CDC, unpublished data, 1998).
      However, VAERS data are limited by underreporting and unknown sensitivity of the reporting system, making it difficult to compare adverse event rates following vaccination reported to VAERS with those from complications following natural disease. Nevertheless, the magnitude of these differences makes it likely that serious adverse events following vaccination occur at a substantially lower rate than following natural disease. In rare cases, a causal relationship between the varicella vaccine and a serious adverse event has been confirmed (e.g., pneumonia in an immunocompromised child or herpes zoster). In some cases, wild-type VZV or other causal organisms have been identified. However, in most cases, data are insufficient to determine a causal association. Of the 14 deaths reported to VAERS, eight had definite other explanations for death, three had other plausible explanations for death, and three had insufficient information to determine causality. One death from natural varicella occurred in a child aged 9 years who died from complications of wild-type VZV 20 months after vaccination.

Development of Herpes Zoster

     The VAERS rate of herpes zoster after varicella vaccination was 2.6/100,000 vaccine doses distributed (CDC, unpublished data, 1998). The incidence of herpes zoster after natural varicella infection among healthy children aged less than 20 years is 68/100,000 person years (7) and, for all ages, 215/100,000 person years (8). However, these rates should be compared cautiously because the latter rates are based on populations monitored for longer time periods than were the vaccinees.
     For PCR-confirmed herpes zoster cases, the range of onset was 25-722 days after vaccination (Merck and Company, Inc., unpublished data, 1998). Cases of herpes zoster have been confirmed by PCR to be caused by both vaccine virus and wild-type virus, suggesting that some herpes zoster cases in vaccinees might result from antecedent natural varicella infection (Merck and Company, Inc., unpublished data, 1998) (9).

Transmission of Vaccine Virus

Transmission of the vaccine virus is rare and has been documented in immunocompetent persons by PCR analysis on only three occasions out of 15 million doses of varicella vaccine distributed. All three cases resulted in mild disease without complications. In one case, a child aged 12 months transmitted the vaccine virus to his pregnant mother (10). The mother elected to terminate the pregnancy, and fetal tissue tested by PCR was negative for varicella vaccine virus. The two other documented cases involved transmission from healthy children aged 1 year to a healthy sibling aged 4 1/2 months and a healthy father, respectively.
Secondary transmission has not been documented in the absence of a vesicular rash postvaccination.

[Vaccination]  [Chickenpox]