Grouping of the vaccinees based on their infection status (Fig. 1d, g) showed that the anti-S1 and anti-N levels were significantly different between HCWs with or without a breakthrough infection at 6 months after the third vaccine dose (non-infected 72 EIA units vs. infected 112 EIA units for S1, p < 0.0001 and 1.4 EIA units vs. 22 EIA units for N, p < 0.0001) after the time point of three months after the third vaccine dose. Here, PSMD1 is linked to infection.