A Sudy to Evaluate the Efficacy and Safety of TNM001 in High-risk Infants

Inclusion Criteria: * 1.High risk infants under 1 year of age who are entering their first RSV season at the time of screening. * 2.Subject's legal representative(s) is(are) able to understand and comply with the requirements and procedures of the protocol,including scheduled visits and sample collection. * 3.Subject is available to complete the follow-up period. Exclusion Criteria: * 1\. Any fever (\> 38.0°C) or acute illness within 7 days prior to randomization * 2\. History of RSV infection * 3\. Being hospitalized at the time of randomization * 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\. Known immunodeficiency including HIV, mother with HIV infection unless the child's infection has been excluded. * 8\. Known allergy history of immunoglobulin products, receipt or expected to receive immunoglobulins or blood products during the study period. * 9.Receipt of RSV vaccine or mAb * 10.Receiving blood products before randomization