scFOS supplemented follow-on formula in healthy infants: Impact on vaccine specific faecal secretory IGA response, faecal bifidobacteria, growth and digestive tolerance

•Intestinal microbiota development in early life plays a crucial role in immune response.•Short-chain fructo-oligosaccharides (scFOS) combined with other oligosaccharides improve immune response in infants formulas.•We evaluated scFOS in follow-on milk formula on immune response to poliovirus vaccination in previously- and never breastfed infants.•scFOS supplemented formula was well tolerated and associated to normal growth.•scFOS supplemented formula did not elicit improved response to the vaccine.•scFOS formula was bifidogenic only in never breastfed infants and on the short term.