L'efficacia of measles vaccine is demonstrated by the fact that entire countries and continents where the majority of children receive 2 doses of vaccine, according to international recommendations, the virus no longer circulates. This applies to the North and South America, Australia, Finland, Sweden, to name a few. Occur in these countries for years now only imported cases from tourists coming or returning from countries where the virus is still widespread.
For the elimination of the virus requires a vaccination coverage of 95% or more because measles is easily transmitted.
The transmission rate (which is determined by a parameter called R0 = basic reproductive rate of the infection) is High: 15-17. Means that in an entirely susceptible population of a patient infected with measles 15 -17 people.
I have prepared some examples that demonstrate the effectiveness of the vaccine against measles:
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Before you continue reading the article, you inform you that since 10.1.11, the Veneto Region has developed an online questionnaire for parents about vaccinations.
Please participate and make run the link as much as possible.
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(All graphs can enlarge by clicking on it)
United States
You can see very well when the vaccination was introduced. The graph represents the number of cases per 100,000 inhabitants. In the era prevaccinale each year, on average, 450 people have died of measles.
The following chart shows the number of measles cases in the U.S. in recent years. The origin of these mini-epidemic is now Always virus imported from any country where it is still widespread.
An argument often used by vaccinia - to demonstrate that the measles vaccine is not effective - is the epidemic of measles in 1990 in the United States. You can read here my criticism to a statement by Dr. Eugene Serravalle in his book "Children supervaccinaoti.
Ex-DDR
Although this example demonstrates the effectiveness of the vaccine. One can see immediately when it was introduced the measles. Initially the children were vaccinated at 9 months but since the percentage of non-responders is higher at this age, in 1980 there was an epidemic. The reason was that since 1971 have accumulated so many people who served susceptible to the virus to spread rapidly. Therefore we made the decision to move the age to 13 months and some years later was introduced the second dose.
Cases of measles
Deaths from measles
Veneto
These graphs allow a comparison between the coverage of vaccination and the epidemic of measles. Only when the coverage exceeds 90%, can be seen disappearing epidemics. A lower percentage to leave a number of likely high enough to allow the virus to circulate.
Even the next four charts show how the impact on the epidemiology of measles vaccination coverage. The arrow indicates the year in which the vaccine was introduced and the initial coverage. In Italy it was very low and the effect was not very comforting.
In England and Wales, the initial coverage was only 50% ...
Source: EPIDEMIOLOGICAL
Reviews Volume 24, page 125-136
September 25, 2002.
"Evolution of Surveillance of Measles, Mumps, and Rubella in England and Wales: Providing the Platform for Evidence-based Vaccination Policy"
In Denmark, the vaccine was introduced much later and the lack of vaccination is known very well in this graph (compared with the previous one) But the initial coverage was 80% and the result is seen.
Source 3-graphs (Italy, England and Wales, Denmark):
| Epidemiol Infect. December 2000; 125 (3) : 635-650. | |
Another example is the former Czechoslovakia that in just 12 years has managed to bring down the number of patients from 320 - 800/100.000 inhabitants (age prevaccinale) to eliminate the virus (in 1982). Era il primo paese del mondo ad introdurre la seconda dose, nel 1975, seguendo un'intuizione che si è rilevata giusta e che già da diversi anni è diventata una raccomandazione internazionale. Nel 1982 la copertura vaccinale di tutta la popolazione tra 1 e 14 anni aveva raggiunto il 98 - 99%!
Vedi i dettagli nel mio articolo Cecoslovacchia 1983: eliminazione del morbillo in tempi record
The reason is easily explained: if even a fraction of the population remains susceptible to measles, the virus remains in circulation, but not so easily reach more children are not immune. So the chances of getting measles is low, spend a few years, the child becomes an adolescent and then adult without having had the opportunity to immunizzarzi against measles. Year after year the number of likely increases until it reached a number sufficient to allow the virus to spread more quickly, resulting in an epidemic.
These outbreaks, however, one aspect diverso da quelle dell'era prevaccinale. Il numero totale dei malati è molto più basso, ma l'età media è più alta, con un'aumentato rischio di serie complicanze. I malati sono composti da persone mai vaccinate contro il morbillo - o perche esiste una vera controindicazione o perché i genitori erano contrari alla vaccinazione o per una dimenticanza etc. - e dai cosiddetti non-responder, cioè quella piccola percentuale dei vaccinati che non ha sviluppato un'immunità o solo un'immunità parziale. Purtroppo nelle epidemie di morbillo si ammalano anche bambini molto piccoli di meno di un anno che non sono ancora stati vaccinati e purtroppo anche loro hanno un più alto rischio di gravi complicazioni.
Se tutti help to achieve and maintain a high level of vaccination coverage, the virus will be taken away the fertile soil on which it can no longer reproduce and which may reach will be protected indirectly by the vaccine. This is an ethical duty of all civil and, and of course a right because the recommendations are protecting their loved ones from measles, either directly or indirectly. Another reason to join the vaccination so that the virus will not be exported to other countries, for example in the Third World, where measles is a disease much more severe than in industrial countries.
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