[1] Univ Helsinki, Fac Biol & Environm Sci, Mol & Integrat Biosci Res Programme, Viikinkaari 9, Helsinki 00790, Finland
[2] Univ Helsinki, Dept Virol, Haartmanninkatu 3, Helsinki 00014, Finland
[3] Univ Helsinki, Dept Oral & Maxillofacial Dis, Haartmanninkatu 1, Helsinki 00014, Finland
[4] Helsinki Univ Hosp, Haartmanninkatu 1, Helsinki 00014, Finland
[5] Univ Helsinki, Dept Infect Dis, Meilahti Vaccine Res Ctr MeVac, Annankatu 32, Helsinki 00029, Finland
[6] Helsinki Univ Hosp, Annankatu 32, Helsinki 00029, Finland
[7] Univ Helsinki, Fac Med, Haartmaninkatu 4, Helsinki 00014, Finland
[8] Univ Helsinki, Dept Otorhinolaryngol & Phoniatr Head & Neck Surg, Helsinki 00029, Finland
[9] Helsinki Univ Hosp, Helsinki 00029, Finland
[10] Tampere Univ, Fac Engn & Nat Sci, Phys Unit, Aerosol Phys Lab, Tampere 33720, Finland
[11] Tech Res Ctr Finland, Visiokatu 4, Tampere 33101, Finland
[12] Finnish Meteorol Inst, Atmospher Composit Res, Erik Palmenin Aukio 1, Helsinki 00560, Finland
[13] Finnish Inst Occupat Hlth, Occupat Safety, Neulaniementie 4, Kuopio 70210, Finland
[14] Univ Helsinki, Vet Biosci, Agnes Sjoberginkatu 2, Helsinki 00014, Finland