Seasonal respiratory syncytial virus prophylaxis based on predetermined dates versus regional surveillance data.

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.