Influenza virus vaccine Sequential influenza-A (H3N2) infection secondary to vaccine failure: case report A 9-year-old girl developed sequential influenza-A (H3N2) infection following influenza virus vaccine failure [route and dosages not stated]. The girl was screened for Oregon Child Absenteeism due to Respiratory Disease Study (ORCHARDS eligibility) on 31 January 2018. On 9 October 2017, she was vaccinated with influenza virus vaccine [quadrivalent inactivated influenza vaccine]. Her family members had also received the 2017/2018 influenza vaccine. On 30 January 2018, she developed influenza‐like illness (ILI) symptoms. Her symptoms included chills, fever, cough, nasal congestion, sore throat, rhinorrhoea, headache, malaise, myalgia, sneezing and anorexia. Following 25h of the ILI symptoms, a home visit was conducted. There was no exposure to farm animals, recent travel or identified sick contact prior to the symptoms onset. Her oropharyngeal and nasal specimens were collected. Rapid influenza diagnostic test (RIDT) test yielded negative results. However, real-time reverse transcription-polymerase chain reaction (rRT‐PCR) was found positive for influenza-A (H3N2), and respiratory pathogen panel was found positive for coronavirus HKU1. At follow‐up, she reported an absenteeism of 2 days and continued sore throat, cough, rhinorrhoea, myalgia, and headache. The rRT‐PCR result from her day 7 swab yielded negative result for influenza. On 7 March 2018, she developed influenza‐like illness (ILI) symptoms. On 9 March 2018, she again screened for a new ILI episode (at the age of 10 years). Following 49h, a home visit was conducted. The symptoms included chills, cough, fever, wheezing, nasal congestion, anorexia, headache, malaise, myalgia, burning eyes and dizziness. There was no exposure to farm animals, recent travel or identified sick contact prior to the symptoms onset. The RIDT result was found positive for influenza-A, and rRT‐PCR results confirmed the presence of influenza-A (H3N2). At follow‐up, she reported an absenteeism of 2 days and continued rhinorrhoea, malaise, fever, cough, chills, headache, myalgia and anorexia. The rRT‐PCR results from her day 7 swab continued to show influenza-A (H3N2). The specimen from each episode were collected on 31 January 2018 and 9 March 2018 for whole‐genome sequencing. The study showed a consensus sequence comparison between the two viruses collected, three single nucleotide polymorphisms (SNPs) were identified within the coding region of the HA protein. Only one SNP was non‐synonymous and resulted in an isoleucine to leucine change at position 67 (in HA1). This particular polymorphism was near 100% frequency in the sequence reads and was four amino acids away from an established antibody epitope site. Author comment: "The period between ILI episodes (37 days), the absence of influenza by PCR at 7‐day follow‐up of the first episode, the resolution of symptoms, and the development of a new ILI support t...
