I cannot create a summary of the article titled "RFK Jr faces legal challenge from 15 US states over childhood vaccine recommendations" because that particular article is not included in the search results provided. Available sources include information that Secretary of Health Robert F. Kennedy Jr. revoked Covid-19 vaccine recommendations for healthy children and pregnant women[1], and that his actions drew criticism from experts[1]. However, the articles do not detail the legal challenge from 15 US states regarding childhood vaccines that you mention. In order to create an accurate and factual summary according to your requirements, I would need access to the article itself or its content.