With all the excitement over Christmas and New Year (we hope you all had a wonderful time by the way!), you might have missed a bit of a change in the guidelines on wound management relating to tetanus prevention.
By the way, this is purely an update blog, so for more information on tetanus generally you can check out my post from 2017 which explains what tetanus is, the UK immunisation schedule, and how we diagnose and treat actual tetanus infections. I won’t go over all that again, but have a read of that then come back here to find out what’s changed. It’s ok, I’ll wait.
Oh good, you’re back! So, as we discussed last time, the Green Book is the very imaginatively titled guide to immunisation against infectious diseases for the UK, published by Public Health England and updated regularly. Initially published in 2013, the chapter on Tetanus was updated at the end of November 2018. Let’s go through what’s changed.
In both guidelines there is a differentiation between tetanus-prone wounds and high-risk tetanus-prone wounds. If the wound doesn’t meet one of the criteria in the prone list, then don’t even start looking at the high-risk list. Some of the criteria have changed, so here are the new ones:
- puncture type wounds acquired in a contaminated environment likely to contain tetanus spores
- wounds with foreign bodies
- compound fractures
- wounds or burns with systemic sepsis
- certain animal bites and scratches (if digging in soil, or an agricultural animal)
High-risk tetanus-prone – any of the above plus one of
- heavy contamination with soil/manure
- wounds/burns with extensive devitalised tissue
- wounds/burns requiring surgical intervention that is delayed for more than six hours
Again, I’ll highlight that a wound cannot be high risk, unless it is first tetanus-prone.
The main changes here are that the extensive devitalised tissue and six hour surgical intervention criteria have moved from the prone list to the high-risk list. This should make a huge difference to our surgical colleagues, and also for those of you in the ED who make regular referrals to surgical/burns/plastics tertiary services (where “tetanus” is usually mentioned as routine in the management plan). At present, these patients now only need to be considered for tetanus-related treatment if the wound meets one of the criteria in the tetanus-prone list in the first instance. Delays in surgery now do not equal automatic immunoglobulin.
Now we’ve decided whether our patient might get tetanus or not, let’s see what we should do with them.
There is a new immunisation recommendations table in the Green Book, and it looks very different to the old one. Like the previous table, it looks quite complicated, but what it boils down to is:
- Child up to date with vaccinations, or adult who has had a booster in the last ten years? No tetanus treatment needed.
- Child who has had primary course (first 3 immunisations) but not up to date with boosters, or adult with last booster more than ten years ago? If tetanus-prone give vaccine. If high-risk give immunoglobulin as well.
- Child who hasn’t had primary course, or anyone with uncertain immunisation status? Vaccines for all. If tetanus-prone give immunoglobulin as well.
You might have noticed a huge change here for our ED practice. Previously, as long as the patient had had all their childhood immunisations, there was no need for a reinforcing dose of vaccine at all. Now PHE recommend repeat vaccination for anyone with a tetanus-prone wound who hasn’t had a booster in the last ten years.
Again, I’ll emphasise this – this is not just anyone with a wound. This is anyone with a tetanus-prone wound (see the criteria above).
We need to make sure we follow the guidelines correctly to ensure our patients don’t receive unnecessary treatment. This is even more crucial with recent shortages in tetanus immunoglobulin in the UK. If you need to give it for prophylaxis, the dose is 250 units IM, or 500 units IM if >24 hours since injury, or heavy contamination, or following burns.
What’s the evidence?
It’s unclear why the guidance has changed, as there’s no explanation in either the Green Book, or the accompanying PHE guidance. One of the new references listed is the new WHO guidance on tetanus immunisation, which was also published at the end of last year. However, their discussion around the topic concludes with “more research needed”, though most published evidence is that long term immunity lasts for 20 years or more.
The most recent study on the topic, by Pool et al, published in Vaccine in March 2018, looked at humoral immunity after tetanus booster immunisation. They found that 100% (CI 91-100) of adolescents and 100% (97.3-100) of adults maintained tetanus antibody levels ≥0.1 IU/ml (sufficient to maintain long-term immunity) ten years after enrolment and immunisation. Numbers were small though, and despite recruiting 2,609 patients at the start of the study, only 175 were available ten years later. This was a study done in the USA as well, so the vaccines are slightly different. Revaxis (UK) actually has double the amount of tetanus toxoid compared with Adacel (used in the study), so it would be interesting to see if this makes a difference.
It would be good to find out what prompted the change to the tetanus guidelines, so if anyone has any ideas, please let us know. I have messaged PHE, and if there are any updates I’ll add them to this blog!