The recent discovery of contaminating porcine circovirus 1 DNA in Rotarix underscores the power of deep sequencing to ensure the purity of viral vaccines. The price of deep sequencing is now low enough that it is possible to use this technology to examine not just viral vaccines, but any biological product produced in mammalian cells for the presence of adventitious agents.
Some individuals have told me they do not want to know what is in their vaccines. Their logic is that even if we do identify a contaminating virus, we might not know if it is of any consequence to human health. But we would nonetheless worry about its presence and unnecessarily spend millions of dollars to remove it. The contrary view is that, although infection with porcine circovirus 1 might be benign, who can be confident that in 20 years the infection will not lead to dire consequences?
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