Ecimens. We also observed that among ERV3 positive swabs, the average ERV3 Ct value for samples positive for any respiratory virus (32.8 cycles) was significantly lower (indicating greater ERV3 load) than the average Ct value (35.4) in samples negative for all viruses (crude difference = 2.0, 95 CI 1.4 ?2.6; Figure 2). Moreover, there was a significant difference in ERV3 Ct values (P = 0.001) in