FIG 2.

Postvaccination receptor-binding domain (RBD)- and nucleoprotein (NP)-binding levels are higher in previously infected individuals. (A to D) RBD-binding (A, B) and NP-binding (C, D) levels for each serum sample are shown by days post-first vaccine dose (68 participants, 178 samples total). (B, D) Serum sample data are labeled based on participants’ prevaccination immune status. Pink, seropositive, 17 participants, 61 samples; orange, seronegative, 31 participants, 87 samples; purple, unknown immune status, 20 participants, 30 samples. Dashed line represents background level for each assay. OD₄₉₀, optical density at 490 nm.