Which vaccines had encephalitis onset closest to 48 hours?

The retrieved evidence does not contain any case of encephalitis with onset at exactly 48 hours after any vaccine.

The closest documented timing is in the COVID-19 vaccine literature, where a case report describes a 72-year-old man with confusion starting 1 day after the first BNT162b2 dose and a Nigerian woman developing suspected autoimmune limbic encephalitis 2 days after the second AstraZeneca dose [4]. Neither is precisely 48 hours, and both are from the previous answer's sources, not from this retrieval.

For childhood vaccines, the evidence here shows no encephalitis cases at any specific hour. The MMR fever peak is at 9-10 days [2], and record-linkage studies looked at encephalitis within 3 months, not at 48 hours [2]. The varicella vaccine strain can cause meningitis and encephalitis, but the case series reports onset in days to weeks, not hours [3].

The IFNAR2 deficiency case documents fatal encephalitis after MMR, but the timing is not given as 48 hours [1]. That case is about a genetic vulnerability, not a specific onset window.

My call: no vaccine in this retrieval has a documented encephalitis case with onset at exactly 48 hours. The closest windows are 1-2 days after COVID-19 vaccines, but the evidence does not support a precise 48-hour pattern for any vaccine. Confidence: low — the retrieval is thin and the question asks for a precision the literature does not provide.