2 questions about the Chicken Pox vaccine...

[ImASecretTwigletNibbler]

Can't find the answer to this anywhere...

1. How long does the first dose take to be effective? It's supposed to be about 80% effective but is that immediate?

1. If a child was already incubating the disease when he had the vaccine, would the vaccine stop him getting the disease or would it be too late by then? Apparently it can be stop the disease within about 3 days of the child being exposed to it but not sure about it they are already incubating it.

netdoctor says this:

The vaccine is given as two doses, separated by at least six weeks. The injections are administered under the skin (subcutaneously) of the upper arm.
The vaccine does not produce maximum immunity against chickenpox infection until about six weeks after the second dose.

it also says this:

This vaccine may not completely protect all individuals who receive it, and it does not produce maximum immunity against chickenpox infection until about six weeks after the second dose. If the vaccine is given to people who are already in the incubation period of chickenpox (ie have been exposed to the virus but are not yet showing symptoms) it will not prevent chickenpox from occuring.

Thanks, powerhoop! That answers the 2nd question but I'm still trying to find out the 1st. I know immunity is not at maximum until 6 weeks after the 2nd dose but I'm wondering how quickly the 80% immunity from the 1st dose sets in.

I'm a secret - you may be misunderstanding that. When vaccines are described as being 80% effective,it does not mean that the vaccine is 80% effective in the individual. It means that if a population are vaccinated, an average of 80% of that population will have immunity - 20% will not.

In this case, after the first dose of the vaccine, around 80% of people will be immune to CP but 20% will not. The second dose is required to catch the 20% of people for which the first dose was not effective.

Hope that makes sense!

Oh goodness, I had completely misunderstood! Thank you for that. So is there any info on how effective one dose is likely to be? I'm wanting my kids jabbed against it before we travel but there won't be time for the 2nd dose before we go.

Where did you get the 80% figure from? If it says that one dose is 80% effective it means that they have an 80% chance of being immune but I"m not sure how long it takes for immunity to kick in if it has worked. If they say that they don't usually consider them fully protected until 6 weeks after the 2nd dose then I would think that it would maybe be 6 weeks to see if the first dose worked too. Sorry I can't be more helpful. If I come across anything I'll let you know!