Seasonal Respiratory Syncytial Virus Prophylaxis Based on Predetermined Dates Versus Regional Surveillance Data

Abstract

In Ontario, Canada, the respiratory syncytial virus (RSV) prophylaxis period onset is defined by a fixed-date set provincially each year and offset by local hospital RSV admission activity. Inaccurate timing can result in inadequate or more costly prophylaxis. RSV positivity (2002/03 to 2010/11) was obtained from a local database. RSV activity was described: season start/end dates, duration and optimum number of palivizumab doses required compared with doses administered for the final 4 RSV seasons (2007 to 2011). Three prophylaxis period-setting methods were evaluated for seasons 2007/08 to 2010/11: 1) the provincial method currently in use, 2) a local fixed-date method based on laboratory data accrued from the previous 5 seasons and 3) an exploratory prospective method based on surveillance of laboratory data. These were compared with the observed RSV seasons. The local RSV pattern closely reflects provincial seasonality. The local median season duration was 125 days (range 90-181). Median season onset and offset dates were December 19 and April 16, respectively. The prophylactic period definitions corresponded similarly, but the provincially set and local fixed-date methods provided longer immunity periods than required for the actual RSV season and involved the administration of more than 5 palivizumab doses compared with the prospective method. The provincial prophylactic period aligned with the local fixed-date and prospective methods. However, the adoption of any of the first 2 strategies merits close observation to minimize excess healthcare expenditure. The prospective surveillance of laboratory isolates should be further explored as a preferred option to better define prophylactic periods.