An open-ended hollow coaxial cable resonator probe configured to receive an aerosol sample for analysis. A metal post shorts the resonator's inner and outer conductors. A metal plate is spaced apart from an open end of the resonator by a dielectric layer that contains the received aerosol sample. Interrogator circuitry coupled to the resonator transmits an electromagnetic wave within the resonator and generates an electric field at the open end of the resonator. The interrogator circuitry is responsive to the generated electric field for determining a resonance frequency and an impedance of the resonator when the aerosol sample is present in the dielectric layer and is configured to identify virus particles in the aerosol sample as a function of the determined resonance frequency and impedance. A portable aerosol analyzer comprises the open-ended hollow coaxial cable resonator and a mouthpiece through which a subject expels a breath sample into the open end of the resonator. Antibodies tethered to high-permittivity nanoparticles attach to pathogens selectively, resulting in enhanced sensing with molecular-level specificity.