Botulinum Toxin for Isolated or Essential Head Tremor Reply

To the Editor: Misset et al. (Oct. 26 issue)(1) reported a significant reduction in mortality among patients with acute respiratory distress syndrome (ARDS) associated with Covid-19 who received plasma from convalescent patients previously hospitalized for Covid-19-associated ARDS. The sex and age of the plasma donors are not reported. Moreover, neither the donors nor the recipients were tested for the presence of autoantibodies that neutralize type I interferons. Such testing would have been important, given that preexisting circulating autoantibodies that neutralize type I interferons may underlie approximately 15% of cases of life-threatening Covid-19 pneumonia and approximately 20% of Covid-19-related deaths.(2,3) Moreover, . . .