"Stealth" virus

There is no evidence that polio vaccine, or any other vaccine, has been contaminated with a "stealth" virus. To our knowledge, existence of this virus as suggested by one researcher has not been confirmed by other investigators.

"Stealth" virus is the label that one researcher has given to a cytopathic virus he has described. He has suggested that such viruses may reside within the body without being detected by the immune system. There is no evidence that polio vaccine, or any other vaccine, has been contaminated with a "stealth" virus. To our knowledge, existence of this virus has not been confirmed by other investigators.

The researcher reports that the "stealth" virus or a related virus has been cultured from the tissues of patients with chronic fatigue syndrome and other chronic neuropsychiatric and autoimmune conditions. He further suggests that the "stealth" virus could be the cause of these illnesses. These findings have not been confirmed by any other investigators. Moreover, it has been stated that the same researcher found similar rates of viral detection among persons with chronic fatigue syndrome and control persons without these illnesses in a blinded study. If a "stealth" virus were a cause of these illnesses, higher rates of infection would be expected among ill persons, compared with healthy control subjects.

He has reported that a partial sequence of this virus is like that of simian cytomegalovirus (SCMV) and suggests that the source of the SCMV-like virus is the African Green monkey. Because African Green monkey kidney cells are used in production of live oral polio vaccine, he hypothesized that the SCMV-like virus ("stealth" virus) may be an adventitious agent in polio vaccines. The researcher's results have not been confirmed in independent laboratories (the usual way to confirm scientific findings) to date.

At a workshop in July 1996, the FDA and National Institutes of Health scientists reviewed some of this scientist's observations. The results presented were considered inconclusive. The need for sharing among scientists of methods and reagents was emphasized so that other workers might independently evaluate the methods and conclusions. FDA considers that the methods applied by the manufacturer to test for SCMV in polio vaccine would detect replicating SCMV.

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