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Faunsdale, AL | That’s true if you’re calling two different diseases, caused by two different viruses, both “measles”. As your summary points out, two different viruses, no cross protection from infection by one virus against infection with the other. MMR vaccine has both antigens in it so in a sense it is cross protective, including mumps.
I think you may not have picked up on the discussion of community spread of the POLIO VIRUS that derives from the oral polio vaccine when that is used.
That is a known problem and is the reason we use killed polio vaccine here instead of the oral type that we used to use. In some ways it’s the best way to have a vaccine. It protects those smart enough to get vaccinated or to vaccinate their children. It does not spread (read cross protect) in the community so those that choose not to be vaccinated are not at risk, but also do not receive any direct protection from inadvertent infections with vaccine derived virus, the vast majority of which will be safe and protective against polio. This was acceptable in the past when your chances of getting wild type polio were high unless you got vaccinated. The rare case of paralytic polio in an unvaccinated person were considered to be probably a result of a wild type virus which was circulating at the time. Once that was not the case after a high uptake of oral polio vaccination had stopped the circulation of wild type polio, and virus typing techniques were available to sequence the genome of viruses, it was discovered that the vaccine virus reverts to a “neurotrophic’ type in the gut of the person given oral polio vaccine and can be shed and infect others that are not immune. A small percentage of these vaccine derived virus cases, as in infections with the wild type virus, result in paralytic polio. It’s the tip of the iceberg phenomenon.
When a person vaccinated with a KILLED polio vaccine comes in contact with a wild or vaccine derived strain of polio, they will get a gut infection but will be protected from paralysis and will then be immune to further gut infections. They WILL shed the virus during that initial gut infection which is a danger to unvaccinated people in the community. Herd effect doesn’t work when the herd is only protected against paralysis. Herd effect works very well if the herd is immune to gut infection, but it’s a question of how to get there without endangering ANYONE. We have decided that it’s best to use the killed polio vaccine here in the USA. Other countries still use the oral vaccine because it is likely to stop polio from circulating in the population when most people have been vaccinated. The cost of a few cases of paralytic polio from vaccine derived polio is considered acceptable compared to the cases that would result from letting the wild type circulate as it would without vaccination.
SHIFTING GEARS HERE!
Prior infection with MEASLES or vaccination against that disease is nearly perfectly protective against any strain of measles (rubeola virus) known. This ain’t the flu that reassorts its H and N groups all the time.
The insinuation was that the prior vaccination campaign for measles caused the current outbreak in Texas which is a crock of ………….
Edited by ccjersey 4/12/2025 14:46
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Measles
