[1] Univ Valladolid, Dept Prevent Med & Publ Hlth, Valladolid 47005, Spain
[2] Hosp Clin Univ Valladolid, Natl Influenza Ctr, Edificio Rondilla, Valladolid 47009, Spain
[3] Complejo Asistencial Univ Leon, Dermatol Serv, Leon 24008, Spain
[4] Hosp Clin Univ Valladolid, Prevent Med & Publ Hlth Serv, Valladolid 47003, Spain
[5] ICSCYL, Inst Estudios Ciencias Salud Castilla & Leon, Soria 24002, Spain
[6] Ctr Invest Biomed Red Enfermedades Infecciosas CIB, Madrid 28029, Spain
[7] Hosp Clin Univ Valladolid, Dept Clin Lab, Valladolid 47009, Spain
[8] Hosp Univ Rio Hortega, Microbiol Serv, Valladolid 47012, Spain