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Author Topic: Heptavac booster timing  (Read 4106 times)

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milliebecks

  • Joined Sep 2015
Heptavac booster timing
« on: February 01, 2018, 04:09:12 pm »
Hopefully a simple question!
I'm lambing a bit later than previously this year. Which is more important: giving the Heptavac booster before the 12 months is up, or leaving it until the ewes are 4 weeks or so from lambing date ......?

Ermingtrude

  • Joined Mar 2017
Re: Heptavac booster timing
« Reply #1 on: February 01, 2018, 04:33:46 pm »
(this isn't an answer, more another question raised about it - sorry ! )

I have had vets say that the Heptavac can be given up to 3 months after the previous years dose, and is fine for the yearly booster - I have done this for my older ewes not in lamb, , so I can use the same pack for the younger pregnant ones. This saves buying more than 1 pack and wasting it. They were sure it was the same as dog vaccines, and up to 3 months over was fine, and no need to restart the course. Different from horses where 1 day over means you have to restart the whole course. Not sure why it is different - all money led, and don't even get me started on why human vaccines can last a lifetime with no boosters....

I have also had vets say that giving the booster a month (and not longer ) before lambing means a better transfer of immunity via mother/lamb way in blood before birth, and colostrum after.

Will be interesting to see replies. I don't object to spending money on stuff when they need it ( and to be fair, I'd sell the house if I needed to, for the dog ! ) but sometimes I wonder about the advice vets give, and the reasoning behind it.

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Heptavac booster timing
« Reply #2 on: February 01, 2018, 04:47:35 pm »
If you're only extending it by a month or two, I'd give the booster at 4 weeks from lambing. You want the ewes to have the maximum concentration of antibodies present in the colostrum in order to give the maximum protection to the lambs. In my book, that trumps any worries about the ewes going a bit over their due date.
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

pharnorth

  • Joined Nov 2013
  • Cambridgeshire
Re: Heptavac booster timing
« Reply #3 on: February 01, 2018, 05:31:45 pm »
The dates given for various vaccines depend on a number of things, most importantly the species and the vaccine itself determine how long on average it will provide immunity.  But for each individual animal it will vary. The dates are set after clinical trials to try to ensure that every animal is covered for the period  given. But immunity does not disappear overnight, think of the shape of a children's slide with the top being full immunity and the immunity becoming less and less over time as you reach the bottom. In other words, if you take 2 sheep one may still have enough immunity at 15 months while another may have insufficient immunity by then.
Of course it would be possible from the clinical trial data to determine the time when say 99.9% of sheep are still protected and make that the re vaccination date, indeed if your Vet says 15 months is ok that is what they are guesstimating, but the Company would not put 15 months on the label as dosing is also about making it as easy as possible for people to get it right and people are far more likely to remember an annual vaccination than one every 15 months.

The horse thing is actually exactly the same scientifically. The 'to the day' bit is imposed by various societies for competitions and is all about compliance and consistency. the horse doesn't lose immunity on day 366, but the chance of not having enough immunity increases each day after that 12 months is up.

I would opt for delaying a short period to get it reasonably close to lambing as the lambs are more vulnerable than the ewes.
« Last Edit: February 01, 2018, 05:35:23 pm by pharnorth »

Ermingtrude

  • Joined Mar 2017
Re: Heptavac booster timing
« Reply #4 on: February 01, 2018, 05:53:35 pm »
The dates given for various vaccines depend on a number of things, most importantly the species and the vaccine itself determine how long on average it will provide immunity.  But for each individual animal it will vary. The dates are set after clinical trials to try to ensure that every animal is covered for the period  given. But immunity does not disappear overnight, think of the shape of a children's slide with the top being full immunity and the immunity becoming less and less over time as you reach the bottom. In other words, if you take 2 sheep one may still have enough immunity at 15 months while another may have insufficient immunity by then.
Of course it would be possible from the clinical trial data to determine the time when say 99.9% of sheep are still protected and make that the re vaccination date, indeed if your Vet says 15 months is ok that is what they are guesstimating, but the Company would not put 15 months on the label as dosing is also about making it as easy as possible for people to get it right and people are far more likely to remember an annual vaccination than one every 15 months.

The horse thing is actually exactly the same scientifically. The 'to the day' bit is imposed by various societies for competitions and is all about compliance and consistency. the horse doesn't lose immunity on day 366, but the chance of not having enough immunity increases each day after that 12 months is up.

I would opt for delaying a short period to get it reasonably close to lambing as the lambs are more vulnerable than the ewes.

I respect your view and explanation entirely, and I am not looking for an argument. I agree that the tailing off of immunisation is going to be a curve, and will always have the quick ones, the slow ones, and the non conformer ones. I just find it interesting that human vaccinations can be life long, when the cost isn't taken by the person, but animal vaccines, where it is, are yearly.  My dog, now 17, had his puppy course at 12 weeks as normal, and 3 boosters. After that, I chose to run yearly  immunology bloods on him, and 14 years later the annual bloods ( cheaper than a booster ) still show he is immune :)

Marches Farmer

  • Joined Dec 2012
  • Herefordshire
Re: Heptavac booster timing
« Reply #5 on: February 01, 2018, 06:37:18 pm »
A bit like the Tetanus jab for humans, perhaps, which used to be given at regular intervals but it's now considered 3 (?) jabs is enough ...?  I give ewes their booster four weeks before the first lamb is due, although that date varies from year to year.

milliebecks

  • Joined Sep 2015
Re: Heptavac booster timing
« Reply #6 on: February 01, 2018, 06:52:54 pm »
Thank you. Great advice, as always!
I'm less than 3 weeks later than last year, so I'll keep to the 3-4 weeks before first due date without worrying.

Black Sheep

  • Joined Sep 2015
  • Briercliffe
    • Monk Hall Farm
Re: Heptavac booster timing
« Reply #7 on: February 01, 2018, 08:13:28 pm »
I just find it interesting that human vaccinations can be life long, when the cost isn't taken by the person, but animal vaccines, where it is, are yearly.

Depends which immunisation for which disease in which creature. Primary dosing and booster periods in humans are very variable and include:

Typhoid: single dose primary course, lasts for 3 years, boosters needed every 3 years
Hepatitis A: single dose primary course, lasts for up to 3 years, but if boosted within this period probably covers for 20 years
Rabies: three dose primary course, first booster needed after 1 year and then at 3-5 year intervals

Variables such as how immunogenic the vaccine is, how it is formulated and the individual response all play a part. The diseases we're immunising livestock against are generally not ones we're immunising humans against. All these complexities mean that the formulation process will be different and it may not be possible to generate a sustained immune memory meaning more regular boosting is needed.

Ermingtrude

  • Joined Mar 2017
Re: Heptavac booster timing
« Reply #8 on: February 01, 2018, 08:33:07 pm »
I don't remember having regular typhoid injections apart from a primary course... I shall now worry the next time I have a cough and cold  !

pharnorth

  • Joined Nov 2013
  • Cambridgeshire
Re: Heptavac booster timing
« Reply #9 on: February 01, 2018, 10:00:25 pm »
[member=169469]Ermingtrude[/member] it is great you do the yearly immunology bloods. I wish there was an easy and reliable way of pooling your data with others to increase vaccination frequencies. It's the wrong place for the debate but I can't help but respond. I have spent time on portfolios for major drug development and there are many ways of looking at it, of course sometimes the vaccination simply is not capable of long term immunology, but if it has potential but perhaps the most compelling reason it is not done is that it is usually more about opportunity costs than short term profit. To do a proper clinical trial (e.g. To take blood immunology over say 10 to 15 years for a dog or cat or sheep) will come from the same pool of funds that can be used to develop a vaccine for a new disease (eg blue tongue) or a better formulation (e.g a version of Heptavac you use over a month rather than 10 hours). And to be brutal human medicines, e.g Alzheimer's, cancer.  So the pet owner spends a bit more on vaccinations and the company makes a few more batches a year and the drug development funds are spent on these other things.  I am not being disrespectful to you or your comments, it s just where I have spent much of my time.

 

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