Predisposing factors for person-to-person transmission of severe fever with thrombocytopenia syndrome bunyavirus.

Person-to-person transmission of severe fever with thrombocytopenia syndrome virus (SFTSV) is a new threat to human health. Here we report an outbreak of nosocomial person-to-person transmission of SFTS. Among eight persons with face-to-face contact distance ≤50 cm and/or exposure time ≥30 min to the index patient, six became infected. Only one of the 17 persons with exposure distance ≥50 cm and exposure time ≤30 min became infected (75% vs 6.25%, P < 0.001). Epidemiological investigation revealed high viral load, bloody secretions and bleeding, exposure time, and distance as the key factors in person-to-person transmission.