Procedures
28 days following vaccination, participants underwent nasal inoculation with Nasal wash samples were collected immediately before and 28 days after vaccination, and after inoculation on days 2, 7, and 14. Sample collection and processing has been previously described.Genomic bacterial DNA was isolated from nasal wash pellets stored in skim milk, tryptone, glucose, and glycerol by means of the Agowa Mag mini-DNA extraction kit (LGC Genomics, Berlin, Germany) as per manufacturer's instruction by means of one of the three samples described previously. The extracted DNA was stored at −20°C for use in 