How effective are Vaccinations?

florodon2

Recent statement from HSE re Measles.

http://www.hpsc.ie/hpsc/News/MainBody,12649,en.aspx

"So far, 42 cases of measles have been reported in Ireland since January 2011. Eight of these cases were in children under 12 months of age who were too young to have been vaccinated but almost half of the rest had not received any doses of MMR vaccine."

As I read it, that means at least half of those who got measles had already been vaccinated. So, the vaccination is, at best, only 50% effective???

EugeneOnegin

Eh, a lot of factors influence the efficacy of vaccines. MMR vaccine is quite good a eliciting protective immunity against mumps, measles and the rubella viruses.

However, vaccines are only good at providing protection against certain strains of bacteria/virus (i.e. the strain in the vaccine itself). I think there is a few examples of the occurrence of strains of measles not included in the vaccine.

But on the whole, vaccine are very good at protective immunity. provided they are specific against the right strain, delivered at the appropriate time and also are immunogenic.

finty

florodon2 wrote: »

Recent statement from HSE re Measles.

http://www.hpsc.ie/hpsc/News/MainBody,12649,en.aspx

"So far, 42 cases of measles have been reported in Ireland since January 2011. Eight of these cases were in children under 12 months of age who were too young to have been vaccinated but almost half of the rest had not received any doses of MMR vaccine."

As I read it, that means at least half of those who got measles had already been vaccinated. So, the vaccination is, at best, only 50% effective???

Interesting interpretation of that data.

around 90% of irish kids get vaccinated, from a total live births of somewhere in the region 70000 a year.

(http://www.independent.ie/health/latest-news/mmr-vaccine-uptake-at-highest-levels-yet-2210365.html)

In one year, 17 immunised kids get measles.

Pretend that those were all under 4 years old. Thats from about 250,000 children immunised.

17/250,000


You interpret that as a 50% effective rate?

The fact that the rate in kids who havent been vaccinated is low too is due to a concept called herd immunity. ie. the fact that most kids are immune means that measles virus isn't circulating in the population and thus the non-immunised kids are not exposed to the virus


http://en.wikipedia.org/wiki/Herd_immunity

Kurtosis

florodon2 wrote: »

"So far, 42 cases of measles have been reported in Ireland since January 2011. Eight of these cases were in children under 12 months of age who were too young to have been vaccinated but almost half of the rest had not received any doses of MMR vaccine."

As I read it, that means at least half of those who got measles had already been vaccinated. So, the vaccination is, at best, only 50% effective???

You are also failing to account for those children who did not receive both doses of the vaccine i.e. at age 12 months and the booster at school age. A single dose of vaccine is not recommended.