Fig. 4

SARS-CoV-2 detection in saliva remains stable following summer and winter shipping conditions. Spiked saliva samples diluted twofold were incubated under summer or winter profiles in triplicate (from Additional file 8: Table S3). Summer profile consisted of 40 °C for 8 h, room temperature for 4 h, 40 °C for 2 h, 28 °C for 36 h, and 40 °C for 6 h. Winter profile consisted of − 20 °C for 8 h, room temperature for 4 h, − 20 °C for 2 h, 4 °C for 36 h, and − 20 °C for 6 h. Samples with invalid Ct values are highlighted in red. a No significant differences were found in N1 Ct values when comparing the profiles to the fresh (control) samples (Kruskal–Wallis; P > 0.05). b The Ct values for RP of samples for the winter profile were significantly higher than fresh samples (Kruskal–Wallis; P < 0.03). The horizontal bars indicate the median Ct value