Rabbi Karr adds: In explaining the Shemoneh Esrei the Gemora cites Scriptural passages explaining why one brocha follows the other one. But, surprisingly a new concept is introduced; that on numbers. Evidently the position number is significant. Not all the numbers but just a few. The first is seven. The Gemora states that the blessing of geulah, redemption, is the seventh blessing of Shemoneh Esrei, as Moshiach will arrive in the seventh year of the Shemitah cycle. When the number seven is mentioned, one immediately thinks of Shabbos. The connection between Shabbos and Moshiach is that when the Jewish people observe the Shabbos properly, the Redemption will come.
The eighth brocha is the brocha of Healing. The mitzva of circumcision is on the eighth day of a child’s life. The mitzva of Bris Milah is only for Jews. This prayer for healing is unique for Jews that have, and receive a different type of healing than non-Jews. The Gemora in Shabbos explains that the body of a Jew is different than a gentile because of the kosher food that we eat and the non-kosher food that they eat. The medicine and healing are different for Jews than non-Jews. Therefore this brocha is number eight to remind us of this fact.
I am adding: Perhaps this is the reason that the brocha concludes by saying rofei cholei amo Yisroel. Although Hashem heals everyone, there is a special type of healing that is uniquely reserved for the Jewish people.