Thread by @petermbenglish

@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids I'm not sure I understand this tweet.

It has long been policy to vaccinate eg HCWs against chickenpox if they are not immune and, using effectively a bigger dose of the same live-attenuated virus vaccine, to vaccinate older people to prevent shingles.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids The live attenuated virus vaccine causes shingles much less often than wild chickenpox virus.

We now have a (more effective) subunit vaccine for shingles. It can't cause shingles.

It has long been argued that shingles is much more serious than chickenpox.…
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids … (Which is true.)

…And that "natural boosting" via exposure to children with chickenpox boosts immunity and thus prevents/delays shingles.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids The evidence base for this is very mixed.

One elegant French study compared shingles rates (and age of onset) between IIRC schoolteachers, 1° care paediatricians, and members of a closed order who had very little contact with children. No natural boosting found in that study.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids Other studies have reached different conclusions but, IMO, the evidenceof benefits from natural boosting is weak.

(BTW, I call it the Hope-Simpson hypothesis. Hope-Simpson is an epidemiological hero of mine - look him up. en.wikipedia.org/wiki/Robert_Ed…)
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids The other - more prosaic but more serious - reason why we don't routinely vaccinate all children in the UK is that it doesn't meet cost-effectiveness thresholds.

The burden of disease is insufficient to justify the costs (£ and adverse reactions) of vaccination.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids Live attenuated vaccines are expensive to make. The risk of accidentally growing a contaminant means extraordinarily high biosecurity standards.

There are also safety issues - immune-suppressed children have died from chickenpox vaccine virus infections IIRC.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids Now we have a well-established subunit shingles vaccine I assume a paediatric chickenpox version of the vaccine will be developed. It will be cheaper (easier to produce), safer (no risk of infection or later vaccine-virus shingles), and…
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids …and might shift the cost-effectiveness ratio in favour of universal childhood vaccination.

BTW…
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids Shingles (aka Herpes zoster) and chickenpox (aka varicella) are caused by the same virus, Herpes varicella-zoster (HVZ). Shingles is a (usually late) complication of chickenpox. The body doesn't usually eradicate the virus, which hides in the nervous system…
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids If immunity wanes sufficiently, the virus pops out in the area served by a single nerve root (a dermatome).
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids in immune suppressed people it can cause disseminated shingles, which can be very serious. (The composer Gerald Finzi died from it.)

And shingles can leave long-term, crippling pain ("post-herpetic neuralgia)". Especially in older people.
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids Shingles can be very unpleasant and is very common.
So get your singles vaccine (when offered it), folks!
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@lisa_iannattone @greg_travis @fitterhappierAJ @COVIDforKids @threadreaderapp unroll