Letters Section Editor: Robert M. Golub, MD, Senior Editor.
In Reply: In response to Dr Klote and colleagues, we detected vaccinia DNA in the blood or oropharynx in 16 (21%) of 77 military members 1 week to 3 weeks after smallpox vaccination using real-time PCR and confirmatory acrylamide gel electrophoresis. Vaccinia DNA was found in the blood of 1 vaccinee (1.96%; 95% CI, 0.05%-10.40%) at 21 days and after scab separation, beyond the recommendation from the US Food and Drug Administration for blood donation deferral. Our article acknowledged that presence of vaccinia DNA does not necessarily translate to the presence of replicating virus. However, only a few orthopox virions may be necessary to establish infection,1 and presence of foreign DNA in the blood 21 days after inoculation raises some concern for infectivity.
Savona MR, Danaher PJ. Vaccinia DNA in Blood After Smallpox Vaccination. JAMA. 2006;296(11):1350-1352. doi:10.1001/jama.296.11.1351