We conducted a preliminary comparison of the relative sensitivity of a cross-section of published HRV-specifi c PCR primer pairs (most of which were fi rst published before HRV-C was reported), independent of most variables described above, by testing a panel of 57 clinical specimen nucleic acid extracts from combined nose and throat swabs from preschool children with colds and infl uenza-like illnesses in Melbourne, Australia. The study was approved by the Royal Children's Hospital Human Research Ethics Committee. The panel included representatives of the 3 HRV species (Figure) , human enteroviruses (HEVs), and extracts negative for picornaviruses. The HRVs had been previously detected by using a nested primer pair (online Appendix Table, www.cdc.gov/EID/content/17/2/294-appT.htm) (5). We used 10 different HRV primer pairs and also retested specimens by using the original primer pair with our standard reagents and equipment (5) . We applied the published T M when possible. The original descriptions of primer pairs 7 and 10 (online Appendix Table) lacked T M information, and after in-house calculations, we used T M s of 50°C and 58°C, respectively. We also deliberately standardized the reagents (OneStep RT-PCR kit, QIA-GEN, Doncaster, Victoria, Australia) and thermal cyclers used (Veriti, Applied Biosystems, Foster City, CA, USA) for conventional PCR and the RotorGene 3000 real-time cycler (QIAGEN). Because primer pair 1 had a published history of detecting types from all HRV species, we chose it to genotype HRV-positive samples by sequencing the amplifi ed products. Other pairs were used if pair 1 was unsuccessful.