IGHA1 and COVID-19: A statistically significant increase in salivary levels in COVID-19 patients compared to healthy controls was detected for all the investigated biomarkers, namely kFLC (p = 1.8 × 10−4, Figure 1A), λFLC (p = 1.4 × 10−8, Figure 1B), k/λ (p = 1.3 × 10−2, Figure 1C), k + λ (p = 6.6 × 10−5, Figure 1D), IgA1 (p = 1.3 × 10−5, Figure 1E), and IgA2 (p = 2.0 × 10−5, Figure 1F).