On the other hand, if some viruses sneak through and infect a cell ; then the body is dependent upon T cells to eliminate the virus, and therein lies the opportunity for us to rethink what we're doing in terms of vaccination -- because those T cells, at least theoretically, could be highly potent and could attenuate the disease. In other words, they wouldn't protect against infection, but they might make infections so asymptomatic that you would not notice it yourself and, in fact, you would never have enough virus in your body to transmit it to somebody else. That's the hypothesis.