Varicella-Zoster Virus Vaccine

5 Jun

The  two  pronged consequences of VZV have been  previously discussed in Chapter 3. In  brief,  childhood chickenpox is one manifestation of VZV. Children  develop immunity  to  the latent virus. The  major risk after this event is  that one’s immunity will wane over time and  the  VZV reactivates, caus- ing painful shingles. As one ages,  the  probability that the VZV will reactivate approaches 50% for those 85 and  older. There are  numerous major benefits from  the  VZV or “chickenpox” vaccine:

1.   Prevention of chickenpox in young  children.

2.   As widespread immunization occurs, there will  be  a reduced reservoir for the  wild virus.

3.   Reduction  in   infant  hydrocephaly associated with maternal VZV infection early in pregnancy (234).

4.   Vaccination in  the  elderly to attenuate the  course of herpes zoster (235,236).

5.   Vaccination  of  others  whose   immune systems are impaired (236).

It is  evident that waning cellular immunity is  strongly correlated with the  development of herpes zoster (237–239). The live attenuated varicella vaccine was approved for anyone aged  1 year or  older  by  the  FDA  in  1995.  The  vaccine was developed in Japan over 30 years ago, yet the  United States is the  only country using it as a universal vaccine against chick- enpox.  Cases of chickenpox and  complications from  chicken- pox  (hospitalizations) have been  reduced. Children usually receive 1 dose  of vaccine, while  those 13 years of age  or older receive 2 doses  1–2 months apart.

One issue has  been  the  degree of efficacy  of the  vaccine. Breakthrough varicella is reported in  10–15%  of vaccinees. Vaccine effectiveness, based on case  studies and  clinical tri- als,  may  range from  <45–90% (240). Another issue has  been the  lasting degree of high  immunity. Vaccine efficacy  seems to be reduced by improper handling and  storage of the  vaccine and  individual response characteristics, such  as  a history of asthma or age  of <14 months at time of immunization, and

short interval (<30  days)   between MMR  inoculation and VZV immunization. Efficacy  may  be  improved by adminis- tering a higher dosage of vaccine and/or more  than one dose in  children. When older   children (>13  years of age)  and adults are  given  two  doses  of VZV vaccine, higher antibody titers are  evident 6 weeks after immunization. In small chil- dren, higher antibody titers  occur  when a  booster dose  is given  (241).

Vaccination with the  Oka  or vaccine strain of VZV rarely causes rash. Breakthrough cases due  to wild  virus tend to be less  severe than cases in  the  non-vaccinated. Breakthrough cases are  less  likely  to cause secondary infection (241).

Investigators are  currently evaluating the  potential for the  live-attenuated vaccine to act as a booster for the  compro- mised cellular immune response in older  individuals. A phase III  clinical trial is underway to investigate this effect  and  to determine any  clinical significance with regard to the  reduc- tion  of severity or  prevention of herpes zoster. The  vaccine under investigation is a more  potent version of the  one  cur- rently licensed for immunization in children.

In later life, VZV plagues the  elderly as painful shingles. Especially painful  are   those that  occur  on  the   face  and involve  the  trigeminal nerve. Levin  et  al.  (242)  have previ- ously  studied the  immune response of elderly persons who received the  live  attenuated  vaccine and  found  that approxi- mately 10–15%  of the  vaccinees failed to  develop increased immunity. Overall, the  calculated half-life of the  enhanced immunity in  this study was  54 months. The  long-term dura- tion  of the  booster effect  had  a positive correlation with the dose of the  administered vaccine. In a follow-up study 6 years after vaccination, Levin  et  al. (243)  found  that the  varicella- zoster virus-responding T cell frequency was still  significantly improved over  initial baseline measurements, as  well  as expected measurements for this age cohort. In this vaccinated population, the frequency of herpes zoster was within the range of expected incident for this age cohort. However, in all cases of herpes zoster in  the  study, the  number of lesions was small, the  associated pain was  minimal, and  postherpetic neuralgia did not occur. This  preliminary study suggests that

vaccination in  the   elderly may  be  able  to  attenuate the course of herpes zoster (235).

Adverse Effects

Fever. Fever is  common (37.7°C  or  100°F), but  a  fever over  39°C  (102°F)  may  be  of more  concern. Patients should check  with their physician.

Injection site. The  injection site   may  be  tender or erythematous but  this should diminish over 2–3 days. Varicella-like  rash. Patients should check  with their doctor  if a rash appears in areas other than the  injec-

tion  site.

These signs and  symptoms are  less common, but  patients should check with their doctor if they continue for an extended period of time or are  more  bothersome than usual:

Abdominal pain.

Common cold or sore throat. Congestion or cough.

Nausea or diarrhea. Rare events.

• Black, tarry stools

• Blood in urine or stools

• Reddening of skin, especially around the  ears

• Airway or swallowing difficulty

• Hives

•  Irritability

• Peripheral itching

(feet or hands)

• Unusual  bleeding or bruising

• Sudden or severe tiredness or weakness

• Muscle or joint  pain

• Pinpoint red macules on skin

• Stiff neck

• Confusion

• Severe or continuing headache

• Facial swelling (eyelids, face, or nasal passage ways,  swollen glands)

• Vomiting

• Patients should check with their doctor  as

soon as possible if any of these rare events occurs.

Special Considerations

Leukemia. Immunized children with leukemia are  less likely  to develop chickenpox or shingles.

Allergies to  neomycin or  gelatin. May  be contraindi- cated for vaccine administration.

Pregnancy or  intent to  become pregnant. Varicella vaccine is not  known to harm the  fetus, but  tests have not  been  done.  However, wild viral infection can  some- times cause birth defects.

Breastfeeding. Mothers who  receive the  vaccine and wish  to breastfeed should consult first with their doctor. Tuberculosis. Although wild virus infection may exacer- bate tuberculosis, there are  no reports that the  vaccine

causes tuberculosis to worsen.

Immune deficiency. Decreased immunity may  increase the chance and  degree of side effects  of the vaccine and/ or decrease the  efficacy  of the  vaccine.

Febrile illness. Febrile illness symptoms may  be  con- fused with possible side  effects  of the  vaccine.

Random Posts

Comments are closed.