Doddery old auntie, catching cold, should be protected from infection (10)

I believe the answer is:

inoculated

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'protected from infection' is the definition.
I can't judge whether this defines the answer.

'doddery old auntie catching cold' is the wordplay.
'doddery' is an anagram indicator.
'catching' is an insertion indicator.
'cold' becomes 'C' (eg on taps).
'old'+'auntie'='oldauntie'
'oldauntie' anagrammed gives 'inoulated'.
'inoulated' going around 'c' is 'INOCULATED'.

'should be' is the link.

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I've seen this clue in the Sydney Morning Herald.

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