The answer is that the outbreak's consistent with the vaccine working about as well as previously thought. This isn't some kind of super-mumps.
Just as a side note, vaccine-resistant strains of pathogens don't tend to be "super"; for the most part, they tend to be pretty seriously weakened compared to the parental strain. That makes sense, because the parental strain is presumably well adapted for its pathogenic lifestyle, and changes in the genome are likely to be away from optimal. That's particularly true because most vaccines either specifically or peripherally target aspects of the pathogen that are particularly important in its lifestyle, so escaping the vaccine-indiced immunity generally means making major changes in a critical aspect of its virulence determinants.
You see this in HIV, it turns out. Some recent studies have tracked HIV over time in series of patients. You can detect changes in the virus in response to the dominant immune response -- as the patient's immune response targets one part of the virus, the virus changes that part and keeps going.
But if that virus now infects a new person (who will respond to different sequences of the virus), the first changes (which are now not necessary) change back, they mutate again until they're close to the concensus sequence of HIV. The changes that the virus underwent to avoid the immune system, therefore, were changes away from general optimality, and given the chance the viruses that mutate back to the starting sequence will rapidly outcompete those immune-selected variants.
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Date: 2006-04-13 07:20 pm (UTC)Just as a side note, vaccine-resistant strains of pathogens don't tend to be "super"; for the most part, they tend to be pretty seriously weakened compared to the parental strain. That makes sense, because the parental strain is presumably well adapted for its pathogenic lifestyle, and changes in the genome are likely to be away from optimal. That's particularly true because most vaccines either specifically or peripherally target aspects of the pathogen that are particularly important in its lifestyle, so escaping the vaccine-indiced immunity generally means making major changes in a critical aspect of its virulence determinants.
You see this in HIV, it turns out. Some recent studies have tracked HIV over time in series of patients. You can detect changes in the virus in response to the dominant immune response -- as the patient's immune response targets one part of the virus, the virus changes that part and keeps going.
But if that virus now infects a new person (who will respond to different sequences of the virus), the first changes (which are now not necessary) change back, they mutate again until they're close to the concensus sequence of HIV. The changes that the virus underwent to avoid the immune system, therefore, were changes away from general optimality, and given the chance the viruses that mutate back to the starting sequence will rapidly outcompete those immune-selected variants.