Do Vaccines Cause Vaccine-Strain Viral Reactivation?

Conclusion | Epidemiological Evidence | Proposed Biological Mechanism | Archives | References


Varicella vaccines can rarely cause zoster due to vaccine-strain viral reactivation. Other vaccines currently routinely recommended to the general population in the U.S.* do not cause vaccine-strain viral reactivation.

Epidemiological Evidence

The 2012 report by the Institute of Medicine (IOM), now called the National Academy of Medicine (NAM), described one study assessing varicella vaccination with vaccine-strain viral reactivation [1]; however, it did not provide convincing evidence due to a lack of validity and precision [2]. One large randomized controlled trial published since the 2012 IOM report and conducted in ten European countries found one unconfirmed case of herpes zoster infection and one papular rash out of 4976 recipients of either the MMR vaccine Priorix and the varicella vaccine Varilrix or the combination MMRV vaccine Priorix-Tetra, all vaccines not used in the U.S. Both of these serious adverse events were reported as recovered or resolved [3].

Proposed Biological Mechanism

Varicella vaccines are live attenuated viral vaccines, and are therefore able to replicate in the body. Generalized rash is reported in 4-6% of recipients. Systemic reactions are uncommon but possible. Mild zoster illness (shingles) resulting from a latent infection with varicella vaccine virus has been reported. Immunodeficiency is a contraindication for most live vaccines, including varicella vaccine. For more information, see the Varicella summary.

The 2012 IOM report described cases of vaccine-strain viral reactivation after varicella vaccination [4-23], and concluded that these cases together presented strong mechanistic evidence supporting an association [2]. In immunodeficient persons, vaccine-strain viral reactivation can result in meningitis [4, 9, 21-23] or encephalitis [11, 20].


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2. Institute of Medicine. In: Stratton K, Ford A, Rusch E, Clayton EW, eds. Adverse Effects of Vaccines: Evidence and Causality. Washington (DC): National Academies Press (US); 2012.
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15. Kramer JM, LaRussa P, Tsai WC, et al. Disseminated vaccine strain varicella as the acquired immunodeficiency syndrome-defining illness in a previously undiagnosed child. Pediatrics 2001;108:E39.
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19. Ota K, Kim V, Lavi S, et al. Vaccine-strain varicella zoster virus causing recurrent herpes zoster in an immunocompetent 2-year-old. The Pediatric infectious disease journal 2008;27:847-8.
20. Chouliaras G, Spoulou V, Quinlivan M, Breuer J, Theodoridou M. Vaccine-associated herpes zoster ophthalmicus [correction of opthalmicus] and encephalitis in an immunocompetent child. Pediatrics 2010;125:e969-72.
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23. Levin MJ, DeBiasi RL, Bostik V, Schmid DS. Herpes zoster with skin lesions and meningitis caused by 2 different genotypes of the Oka varicella-zoster virus vaccine. J Infect Dis 2008;198:1444-7.