Varicella does not appear to be a cofactor for human immunodeficiency virus infection in children

A review of the varicella vaccine in immunocompromised individuals

BACKGROUND

Individuals with underlying cell-mediated immunodeficiency disorders are at high risk of developing severe, life-threatening illness associated with varicella-zoster virus infection. A live-attenuated varicella vaccine is recommended for routine childhood immunisation in some countries. In healthy children, the vaccine is efficacious and safe but because immunocompromised individuals may be unable to limit replication of live-attenuated vaccine viruses, the varicella vaccine is not recommended for them and there are few exceptions.

OBJECTIVES

The purpose of this paper is to review the published studies addressing the use of the varicella vaccine in people with cell-mediated immunodeficiency disorders.

METHODS

A computerised search on the PubMed database was used to collect the relevant papers published up to March 2003.

RESULTS

The varicella vaccine has been extensively studied in susceptible children with acute lymphoblastic leukaemia in remission, but studies involving individuals with other immunodeficiency disorders are scarce. Some of the current recommendations are based on very few and small studies with short follow-up. Immunocompromised individuals should be given the varicella vaccine only with complete knowledge of their clinical and immunological conditions and after considering the risks of natural infection and vaccination.

Varicella outbreak at a summer camp for human immunodeficiency virus-infected children

OBJECTIVES

Varicella can result in severe, persistent, or recurrent disease in human immunodeficiency virus (HIV)-infected children. In the summer of 1997, we were notified of a suspected varicella outbreak among attendees of a summer camp for HIV-infected children. We investigated this outbreak to determine the extent and sequelae of the outbreak, and to identify factors that contributed to the outbreak to identify measures for preventing such outbreaks at the camp in the future.

DESIGN

To identify varicella-susceptible persons and those developing varicella after camp and to evaluate the camp's varicella prevention measures, we reviewed camp records for the 110 campers and 96 staff at the implicated camp session, mailed questionnaires to the campers' parents/guardians and physicians, and interviewed susceptible staff. We defined a case as varicella in a person who attended the session with onset </=21 days after the session ended.

RESULTS

Eleven of 31 susceptible children (36%) and 2 of 4 susceptible adults developed varicella. Two children were hospitalized. One developed cellulitis. Cases occurred among children in 5 of 15 cabins. The most likely index case was a child with active zoster at camp, reported to the camp after the session ended. The camp had varicella-prevention measures in place, but the varicella-susceptibility and exposure information provided to the camp was often incomplete or inaccurate. Staff with no varicella history underwent serologic testing, but susceptible staff members were not vaccinated.

CONCLUSIONS

Widespread varicella transmission occurred at the camp. A case of zoster was the most likely source. The risk for such outbreaks can be minimized through vaccinating susceptible staff members, considering vaccination for asymptomatic or mildly symptomatic HIV-infected children according to Advisory Committee on Immunization Practices and American Academy of Pediatrics guidelines, rigorously collecting recent varicella and zoster exposure information, excluding anyone with active varicella or zoster or with recent varicella or zoster exposure, and considering varicella and zoster exposures at camp to be potentially camp-wide.varicella, human immunodeficiency virus infections, disease outbreaks, intravenous immunoglobulin.

Sequential use of intravenous and oral acyclovir in the therapy of varicella in immunocompromised children

BACKGROUND

Immunocompromised children are at risk for disseminated varicella infections. Standard management involves hospitalization and intravenous acyclovir for 7 to 10 days. This approach is expensive, is inconvenient and may not be necessary. We undertook a pilot study to assess the safety and efficacy of an alternative approach that utilized a combination of intravenous (i.v.) followed by oral (p.o) acyclovir in a cohort of immunocompromised children.

METHODS

The cohort consisted of 26 immunocompromised children between the ages of 1.5 and 12.7 years (mean, 6.3). Therapy was commenced with i.v. acyclovir (1500 mg/m2/day in 3 divided doses). Concurrent management included holding or reducing immunosuppressive therapy (by 50%) and administering varicella-zoster immunoglobulin in 69% (11 of 16) of cases where exposure to chickenpox was recognized. Patients were eligible to switch to p.o therapy after receiving a minimum of 48 h of i.v. acyclovir therapy provided they were afebrile; had no new lesions for 24 h; had no internal organ involvement and were able to tolerate oral medications. Patients were observed in hospital for a further 24 h and then discharged provided they remained well. Oral acyclovir was continued for a total of 7 to 10 days (i.v. plus p.o).

RESULTS

Of the 26 patients 25 were successfully switched from i.v. to p.o after 4.1 +/- 1.2 days (mean +/- SD) (range, 2.3 to 6) Children had fever for a mean of 2.0 +/- 1.6 days (range, 0 to 5) and developed new lesions for 2.9 +/- 0.7 days (range, 2 to 4). All 25 patients switched to p.o therapy had resolution of their disease and no patient required resumption of i.v. therapy.

CONCLUSIONS

The sequential use of i.v. followed by p.o acyclovir is feasible in the treatment of varicella in immunocompromised children and results in a reduction in duration of intravenous therapy and hospitalization.

Live attenuated varicella vaccine

Varicella-zoster virus (VZV) is a ubiquitous human pathogen that causes varicella, commonly called chicken pox; establishes latency; and reactivates as herpes zoster, referred to as shingles. A live attenuated varicella vaccine, derived from the Oka strain of VZV has clinical efficacy for the prevention of varicella. The vaccine induces persistent immunity to VZV in healthy children and adults. Immunization against VZV also has the potential to lower the risk of reactivation of latent virus. The varicella vaccine may eventually reduce or eliminate herpes zoster, which is a serious problem for elderly and immunocompromised individuals.

The varicella vaccine. Clinical trials in immunocompromised individuals

A review of the use of live attenuated varicella vaccine in immunocompromised children, particularly those with underlying leukemia in remission, is presented. Data concerning safety, immunogenicity, and efficacy of this vaccine in high-risk children are reviewed. The unique contributions toward our understanding of varicella vaccine, including spread of vaccine-type virus, incidence of zoster, and immune correlates provided by studies of immunocompromised patients are discussed. The importance of protecting high-risk children against severe varicella by the use of varicella vaccine is apparent.

Frequent recurrence and persistence of varicella-zoster virus infections in children infected with human immunodeficiency virus type 1

OBJECTIVE

To examine complications and treatment of varicella-zoster virus (VZV) infections in children infected with human immunodeficiency virus type 1 (HIV-1).

METHODS

Cases of VZV infection were identified retrospectively by reports to the department of health services and review of medical charts. The CD4+ cell counts were correlated with severity and frequency of VZV episodes.

RESULTS

We identified 117 episodes of VZV infection in 73 HIV-1-infected children between Aug. 21, 1986, and Dec. 1, 1993. The most common complications were recurrence and persistence; 38 children (53%) had 69 recurrent episodes of VZV infection. The majority of children (61%) had zoster during the first recurrent episode, and 32% had a disseminated eruption typical of varicella. There was a strong association between an increasing number of episodes of VZV infection and low CD4+ cell count (p = 0.0008). In a subgroup followed for at least 2 years after their primary varicella episode, 10 of 22 children had a recurrence. Persistence of VZV infection was documented in 10 of 73 children, whereas other complications were rare. Thirty-three children (45%) were hospitalized and received acyclovir intravenously.

CONCLUSION

Primary, recurrent, and persistent VZV infections are a frequent cause of morbidity and hospitalization for HIV-1-infected children. Studies of improved preventive and therapeutic agents are urgently needed in this population.