A Trial to Evaluate the Efficacy and Safety of TNM001 for the Prevention of Lower Respiratory Tract Infection Caused by Respiratory Syncytial Virus in Infants

Inclusion Criteria: * 1\. Early and mid-term preterm infants (\<35 weeks 0 day GA) and late preterm infants or full-term infants (≥35 weeks 0 day GA) under 1 year of age, with or without Congenital Heart Disease (CHD) or premature infants Chronic Lung Disease (CLD)，who are entering their first RSV season at the time of screening. Exclusion Criteria: * 1\. Any fever (\> 38.0°C) or acute illness within 7 days prior to randomization * 2\. History of RSV infection or active RSV infection prior to, or at the time of, randomization * 3\. Drug medication prior to randomization or expected to be treated by medicines during the study period. * 4\. Currently receiving or expected to receive immunosuppressive therapy during the study period. * 5\. Renal impairment or hepatic dysfunction * 6\. Nervous system disease or neuromuscular disease * 7\. Prior history of a suspected or actual acute life-threatening event * 8\. Known immunodeficiency including HIV, mother with HIV infection unless the child's infection has been excluded. * 9\. Known allergy history of immunoglobulin products, receipt or expected to receive immunoglobulins or blood products during the study period. * 10.Receipt of RSV vaccine or mAb