[A preliminary study on the disappearance time of influenza virus antigen]

To investigate the antigen clearance time, time to symptom disappearance, and the association between them using immunofluorescence assay for dynamic monitoring of influenza virus antigen in children with influenza.

A total of 1 063 children suspected of influenza who visited the Hunan People's Hospital from March to April, 2016 were enrolled. The influenza A/B virus antigen detection kit (immunofluorescence assay) was used for influenza virus antigen detection. The children with positive results were given oseltamivir as the antiviral therapy and were asked to re-examine influenza virus antigen at 5, 5-7, and 7 days after onset.

Of all children suspected of influenza, 560 (52.68%) had an influenza virus infection. A total of 215 children with influenza virus infection were followed up. The clearance rate of influenza virus antigen was 9.8% (21 cases) within 5 days after onset. The cumulative clearance rate of influenza virus antigen was 32.1% (69 cases) within 5-7 days, and 98.1% (211 cases) within 7-10 days after onset. Among these children, 6 children (2.8%) achieved the improvement in clinical symptoms within 3 days after onset. The cumulative rate of symptom improvement was 84.7% (182 cases) within 3-5 days after onset, and 100% achieved the improvement after 5 days of onset.

The time to improvement in symptoms after treatment is earlier than antigen clearance time. Almost all of the children achieve influenza virus antigen clearance 7-10 days after onset. Therefore, it is relatively safe for children to go back to school within 7-10 days after onset when symptoms disappear.