A virus is an ultramicroscopic infectious organism that, having no independent metabolic activity, can replicate only within a cell of another host organism. A virus consists of a core of nucleic acid, either RNA or DNA, surrounded by a coating of antigenic protein and sometimes a lipid layer surrounds it as well. The virus provides the genetic code for replication, and the host cell provides the necessary energy and raw materials. There are more than 200 …showed first 75 words of 1505 total…

…showed last 75 words of 1505 total…may never be synthesized. The kind of research needed to develop a modified live virus vaccine simply could not be done, given the scope of the problem. That is, only a few people would be working in labs who would need to be vaccinated, and a vaccine might want to stockpile in the event of an epidemic. Nevertheless, these are not the scale of circumstances under which the development of a vaccine could be afforded.