[UPDATE] The main protection mechanism provided by the Cryptowall Vaccine relied on exploiting a programming flaw in the Cryptowall Trojan itself. The Cryptowall operators have modified the way they check whether a system has been infected or not, which renders the Cryptowall Vaccine ineffective in some cases.
Because we cannot guarantee the proper functioning of the vaccine anymore, we decided to discontinue providing the tool. Stay tuned for further updates.
Meanwhile, please consider implementing the measures delineated here.