Abstract
Severe fever with thrombocytopenia syndrome (SFTS), a newly emerging tick-borne viral disease, has been detected in Asia since 2009, and person-to-person transmission is possible. SFTS is characterized by atypical signs, including mild to severe febrile illness similar to that associated with hemorrhagic fever, with 16.2 to 30% mortality. We found that the titers of neutralizing antibodies, play an important role in protective immunity, to SFTS virus (SFTSV) in survivors and healthy residents who lived in endemic areas and who were positive for SFTSV IgG, were higher than those in non-survivor patients. Moreover, the titers were maintained in surviving patients and healthy residents but not in non-surviving patients in South Korea.