07-09-12, 07:07 PM #1
Herd Immunity - HPV
Does anyone know of any other case of this?
The human papillomavirus vaccine provides a benefit to women even if they are not vaccinated, via a phenomenon known as herd immunity, a new study suggests.
Among the women in the study, there was a decrease in the percentage who were infected with the four HPV strains included in the vaccine (HPV 6, 11, 16, and 18) in the years after the vaccine was introduced, compared with earlier years.
This decrease in HPV prevalence was seen among both vaccinated and unvaccinated women, the researchers said.....
07-09-12, 08:43 PM #2
Herd immunity is a phenomenon that occurs in other species, not just humans. It's somewhat analogous to the concept of a firewall.
There is no hard and fast figure defining the threshold of herd immunity, but it appears to generally mainfest in the low 80% range, with a few diseases requiring 90% and a few down in the 70's. It depends on how virulent the disease is, and the way it transmitted.
The concept is, basically, that if (to pick a round number) 85% of the individuals in a population are immune to (say) mumps, then the mumps virus has a very difficult time finding a host that is not immune. It can't jump from host to host like it would in a population with a lower immunity rate, because everywhere a virus cell tries to jump it encounters an individual with immunity, so it dies. Eventually one cell may find a host, and a few cases of infection will always exist, but the success rate is so low that the disease can never achieve epidemic proportions.
This can occur with natural immunity, but more importantly, it can be induced with a vaccination program. The premise is that if you only succeed in immunizing 85% of your children against mumps, you have impaired the spread of the disease. While it is not truly eradicated, it is so rare that it can never become an epidemic.
This is of critical importance in contemporary America because of the strong anti-science sentiment within the Religious Redneck Retard Revival. Some of these people are convinced that vaccination is a government plot to establish mind control over their children, or to re-engineer their DNA to cause their grandchildren to be atheists, or some such gobbledygook.
The herd immunity phenomenon tells us that as many as 15% of a community (depending on the disease) can refuse to vaccinate their children, and the 85% who are vaccinated comprise a firewall to prevent the disease from becoming an epidemic.
07-09-12, 08:45 PM #3
so if all the kids get immunized against chicken pox, the kids who aren't immunized won't get chicken pox because there won't be anyone to give it to them??
07-09-12, 08:55 PM #4
If most of the children are immunized, very few of the ones who aren't immunized will get it because most won't come in contact with the few who have already got it. If a virus cell jumps to one of the many hosts that are immunized, it will die. This reduces the total number of virus cells in the community.
07-11-12, 06:35 AM #5
07-11-12, 06:45 AM #6
so herd immunity does not presume the passage of immunization bodies from immunized kid to non-immunized kid?
07-11-12, 06:53 AM #7
The magic number for how many people need to be immunized to stop a disease spreading depends on things like how contagious the disease is and how interactive the community is.
For highly contagious diseases like whooping cough and measles, better than 90% immunity is needed to prevent epidemics.
Note that 100% immunity is not achievable - there will always be people (newborns, others with certain immune disorders or allergies) who are not yet vaccinated or can not be vaccinated.
07-11-12, 06:54 AM #8
By ricardonest in forum Biology & GeneticsLast Post: 01-25-12, 01:53 PMReplies: 0
By Brian Foley in forum World EventsLast Post: 05-26-09, 09:29 PMReplies: 3
By charles brough in forum Science & SocietyLast Post: 12-01-07, 10:26 AMReplies: 0
By otheadp in forum World EventsLast Post: 11-14-07, 09:49 PMReplies: 9
By S.A.M. in forum PoliticsLast Post: 11-02-07, 09:22 AMReplies: 51