Preparation of vaccine and placebo
Recipharm AB
STERILE, COLD
The vaccine and placebo doses were prepared by unblinded study nurses. For the vaccine group, the content of the dmLT ampoule (700 μg) was reconstituted with 700 μl sterile water and, after dissolving, diluted 1:5 in PBS solution (APL, Sweden) in a 2-ml Eppendorf-tube and refrigerated (2–8°C). The solution was used within 6 h.Each vaccine dose was prepared by dissolving the sodium bicarbonate (Recipharm AB, Stockholm, Sweden) buffer in 150 ml of cold water and, after dissolving, adding the content of the vaccine vial, followed by 50 μl of dmLT (200 μg/ml) and stirring. The placebo was prepared by dissolving the sodium bicarbonate buffer in 150 ml of cold water. Vaccine and placebo were ingested orally within 30 min after preparation. They were served in white porcelain cups making them indistinguishable from each other, nor was there any obvious dissimilarity in taste.