Children under 5?years of age are the group predominantly responsible for transmission,70 suggesting that by vaccinating this age group it is likely that a reduction in disease in unvaccinated age groups would also be seen. which has inhibited infant responses to pertussis, diphtheria and some CRM-conjugated vaccine antigens in the routine infant schedule.69 Should this be the case, this would further support the argument to limit maternal RSV immunisation to those children expected to be born in an at-risk period. Herd immunity In addition to providing direct protection, active paediatric RSV immunisation could potentially provide benefits through reduced circulation of the RSV virus (herd immunity) if long-term immunity is induced. Children under 5?years of age are the group predominantly responsible for transmission,70 suggesting that by vaccinating this age group it is likely that a reduction in disease in unvaccinated age groups would also be seen. Modelling work by Yamin ET?AL. and Poletti em ET?AL /em . suggest that immunisation strategies to ensure immunity across this age range could reduce RSV burden in infants and adults.70,71 Future studies using immunogenicity data from Somatostatin phase II and III trials, once available, should inform these models further. Passive immunisation Passive immunisation with monoclonal antibody (palivizumab) has been used widely in high risk populations as an effective method to protect such individuals from RSV infection, and this is the only approach to RSV prevention with proven efficacy. A seasonal course of monthly immunisations over five months is the preferred schedule given to high-risk preterms in most temperate climate countries. Two new monoclonal antibodies recently entered clinical trials. In 2015, a phase III clinical trial started comparing a one or two-dose schedule of a monoclonal antibody to placebo in healthy preterm children; unfortunately this has recently been stopped due to lack of efficacy and further development of this product has been halted.8,9 In 2016, a PSTPIP1 phase IIb trial started comparing a one Cdose monoclonal antibody to placebo in healthy preterm children using altered Fc binding to generate an extended half life.7 If a single dose of the monoclonal antibody in development at the beginning of RSV season could provide 5?months protection,72 this could Somatostatin potentially provide the most direct way of preventing the seasonal peak of RSV disease in temperate countries, during the age of highest vulnerability and (depending on cost effectiveness) could be expanded from high risk infants to all children entering their first RSV season. An effective annual, universal campaign of this nature could render unnecessary maternal and active infant immunisation in temperate climates. However, unlike active infant immunisation it could not provide herd immunity, as children would acquire RSV infections in their second RSV season. In contrast, in tropical regions children would become susceptible from 5?months of age, although this could still protect infants during the age of highest vulnerability. The use of monthly immunisations with palivizumab over a 6?month period to at risk preterm newborns in Taiwan was shown to be effective in reducing RSV related hospitalisations across their prolonged (10?month) RSV season by 86% within 6?months after discharge independently of the time of the year.50,73 Alternative schedules may need to be applied to cover the different patterns of RSV season. Other areas with perennial RSV season such as coastal areas in the sub/tropical regions face the same dilemma observed in Taiwan.13 The use of monoclonal antibodies to provide optimal reduction in the burden of Somatostatin RSV disease would require administration to all children within the first few weeks of life. The feasibility of this would, of course be heavily dependent on the cost of this product; which would need to be significantly lower than the estimated average 2016C2017 seasonal cost of palivizumab treatment per child which ranges from $3221 to $12,568, (2500-9600; 2725- 10625) for this to be affordable.74 Conclusion The benefits of an RSV immunisation programme that selectively immunises children born at.