Dual and Triple Infections With Influenza A and B Viruses: A Case-Control Study in Southern Brazil Tatiana Schäffer Gregianini, Ivana R Santos Varella, Patricia Fisch, Letícia Garay Martins, Ana B G Veiga Downloaded from https://academic.oup.com/jid/article/220/6/961/5481580 by guest on 31 May 2022