Imaofthree, I googled it & found these statements:
“Haraidim remember the victims of the Holocaust on traditional days of mourning which were already in place before the Holocaust, such as Tisha B’Av in the summer, and the Tenth of Tevet, in the winter”
“Thus, a situation has come into existence where religious forms of commemoration take place primarily on the Tenth of Tevet and on Tisha b’Av, while secular forms of commemoration take place primarily on Yom HaShoah, and either part of the population ignores the other’s day of commemoration”
…maybe someone can verify this???