This is an exploratory study and therefore objectives are not defined as primary and secondary. All objectives of this study are exploratory. These are listed here: Part 1 Objectives •To confirm the planned dose of Palivizumab to be given to participants in Part 2 •To assess safety of Palivizumab in healthy adults Part 2 Objectives •To estimate the margin and variance of prophylactic effect of Intravenous (IV) treatment with Palivizumab administered 1 day prior to inoculation in the RSV human challenge model in healthy adults compared to Placebo [assessed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR)]. •To estimate the margin and variance of prophylactic effect of IV treatment with Palivizumab administered 1 day prior to inoculation in the RSV human challenge model in healthy adults compared to Placebo [assessed by cell culture (pfu/mL)]. •To estimate the margin and variance of prophylactic effect of IV treatment with Palivizumab administered 1 day prior