Duration of antiviral immunity after smallpox vaccination

Erika Hammarlund, Matthew W. Lewis, Scott G. Hansen, Lisa I. Strelow, Jay A. Nelson, Gary J. Sexton, Jon M. Hanifin, Mark K. Slifka

Research output: Contribution to journalArticlepeer-review

693 Scopus citations


Although naturally occurring smallpox was eliminated through the efforts of the World Health Organization Global Eradication Program, it remains possible that smallpox could be intentionally released. Here we examine the magnitude and duration of antiviral immunity induced by one or more smallpox vaccinations. We found that more than 90% of volunteers vaccinated 25-75 years ago still maintain substantial humoral or cellular immunity (or both) against vaccinia, the virus used to vaccinate against smallpox. Antiviral antibody responses remained stable between 1-75 years after vaccination, whereas antiviral T-cell responses declined slowly, with a half-life of 8-15 years. If these levels of immunity are considered to be at least partially protective, then the morbidity and mortality associated with an intentional smallpox outbreak would be substantially reduced because of preexisting immunity in a large number of previously vaccinated individuals.

Original languageEnglish (US)
Pages (from-to)1131-1137
Number of pages7
JournalNature medicine
Issue number9
StatePublished - Sep 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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