Recurrent episodes ( getting chickenpox twice )

• conventional wisdom stated by eminent textbooks is that it is not possible to get chickenpox twice - the argument claims that a single chickenpox infection provides subsequent lifelong immunity
• however it is argued (1) that if immunity was lifelong then shingles would not occur since this represents a localised reactivation of the virus (indicating a failure of immunological control of latency)
• there is evidence that true re-infection with chickenpox can occur (2)
  • twenty-three healthy and apparently immunocompetent children with a history of 2-5 episodes of chickenpox were studied after repeat disease
  • serial sera were tested for VZV-IgG subclass patterns and VZV IgG and G-subclass antibody avidity by urea elution enzyme linked immunoassay (ELISA)
  • of 11 patients studied within 8 weeks of repeat chickenpox (Early Group), mean antibody avidity was significantly lower (31.3 +/- 26.81) than control (65.1 +/- 12.38) (P < .001). Seven had low avidity antibody (< 30 percent) and an abundance of IgG3 which was a pattern like primary chickenpox, and 2/11 had high avidity antibody characteristic of anamnestic responses. Early Group patients and 12 others studied over 8 weeks after repeat disease (Late Group) showed avidity maturation and attrition of IgG subclass antibodies other than IgG1
  • at least nine children failed to show VZV-specific secondary (memory) immune responses early in the course of repeat disease. It is possible that failure to maintain or evoke a secondary immune response could explain their susceptibility to repeat chickenpox.
• there is also evidence that chickenpox infection has occurred in patients who have been vaccinated and been demonstrated to have antibody and cellular immunity against varicella-zoster virus - in these cases virus typing has demonstrated wild-type virus and not vaccine strain, therefore confirming new infection

Reference:

1. Pulse (2003), 63 (26), 88.
2. Varicella-zoster virus antibody avidity and IgG-subclass patterns in children with recurrent chickenpox. J Med Virol. 1994 Jun;43(2):119-24.