Vaccination according to PCR result.

PCR real-time reverse transcription-polymerase chain reaction. CI Confidence Interval. LR Likelihood ratio.
aAny vaccination ever recorded in the Vaccine Information System.
b.A patient was considered immunized with the 2011–2012 influenza seasonal vaccine if the vaccine was recorded in the Vaccine Information System as administered more than 14 days before the date of the ILI onset or if the patients reported vaccination more than two weeks before symptoms onset.
cData from 1,086 (288 positive and 798 negative) patients vaccinated 15 or more days before onset of symptoms according to the information in the Vaccine Information System out of 1,169 classified as immunized because of information retrieved from the Vaccine Information System or by patient's recall of vaccination two weeks before symptoms onset.
Vaccination according to PCR result.