This is serious spontaneous case, initially received on 08-Jan-2018, reported by other health professional and concerns a female patient of unspecified age. The patient had no relevant medical history, no drug history, allergies or any other conditions. Relevant concomitant medications were not reported. On 16-Oct-2017, the patient was administered with FLUCELVAX QIV (anatomical location: left deltoid muscle, batch number: 195250, expiry date: 30-Jun-2018, dose, route of administration: not reported). On 01-Jan-2018, after 2 months 17 days of vaccination, the patient experienced mild flu symptoms such as fever, headache, nausea, fatigue and diarrhea (symptoms were mild). However, she could function at home and hence, no hospitalization was needed. On 03-Jan-2018, after vaccination, the patient was diagnosed with type A influenza after appropriate investigation (unspecified). The reporter was not sure if polymerase chain reaction (PCR) was done. The patient took DAYQUIL, NYQUIL, and ZICAM for the treatment of the events. It was reported that, the event influenza A infection occurred due to lack of efficacy of FLUCELVAX QIV. This case was associated with product quality assurance investigation report (QAIR) and the corresponding reference number was 1027218. The QA investigation performed concluded that FLUCELVAX 195250 was manufactured in compliance with the approved internal procedures and in accordance with the quality requirements. No evidence was found that the LOE (lack of efficacy) complaint was the result of the Fill Finish or Bulk manufacturing process and no trends were identified for the batch, or any other FLUCELVAX QIV batches from the 2017-2018 FLUCELVAX Commercial season. Therefore, no internal root cause was confirmed. On 05-Jan-2018, the patient recovered from all the symptoms (reported as free from symptoms). Follow-up received from the reporter on 18-Jan-2018: Non-significant follow-up received with QA reference number (1027218). Narrative was amended accordingly. Follow-up received from other health professional on 08-Feb-2018: It was reported that, the patient had no medical history, no drug history, allergies or any other conditions. The patient experienced mild flu symptoms such as fever, headache, nausea, fatigue and diarrhea. However, she could function at home and hence, no hospitalization was needed. On 03-Jan-2018, the patient was diagnosed with Influenza A infection (added start date in event tab). She took DAYQUIL, NYQUIL, and ZICAM for the treatment of the event (added in product tab). The reporter was not sure if the patient had PCR (polymerase chain reaction) done. On 05-Jan-2018, the patient recovered from the event (type A influenza). The narrative was amended accordingly. Follow-up received from the quality assurance (QA) department on 08-Mar-2018. The QA investigation was performed and it was concluded that FLUCELVAX 195250 was manufactured in compliance with the approved internal procedures and in accordance with the quality requirements. No evidence was found that the LOE (lack of efficacy) complaint was the result of the Fill Finish or Bulk manufacturing process and no trends were identified for the batch, or any other FLUCELVAX QIV batches from the 2017-2018 FLUCELVAX Commercial season. Therefore, no internal root cause was confirmed. Narrative was amended accordingly. Update 04-Jul-2018: Non-significant case correction received with IRD 08-Feb-2018: The case comment was reframed. No changes were done in the narrative.