sickle cell anemia is autosomal recessive (I believe)
so if q = 0.05, then p = 0.95
full blow disease would then homozygous dominant (p^2 = 0.90) <-- WRONG
heterozygous = 2pq = 2(0.95)(0.05) = 0.095
EDIT: full blown disease = homozygous recessive (q^2), sorry