First of, the study does note that iOS is more secure than Android in protecting against your everyday, run of the mill malware. Considering the attention that Apple places on every app that submits an application for inclusion in the App Store, that is not surprising. After all, iOS is NOT an open system like Android is. The problem for iOS users here is that if they jailbreak their device, the high wall that protects an iOS device is gone and the malware will infest iOS the same as it would an Android device. Because Android is an open source system, the protection against malware must come from the developers who must be sure that they are not downloading an infection.
In the report, Symantec concludes that iOS is best at "resisting malware attacks, resource abuse/service attacks, data loss and data integrity attacks." Android is better than iOS in specific security features. Symantec says that Google's open source OS is better than iOS when it comes to isolating processes, but is behind on "access control, application provenance and encryption."
Where Android really has an advantage is in the number of vulnerable points which Symantec says numbers 200 on iOS versus just 18 on Android. And of that 18, only 4 remain unpatched by Google. The latter also beats Apple when it comes to the speed of patching an 'opening', taking just 8 days to come up with a solution versus 12 days for the Cupertino based firm.
Symantec's conclusion is that even with the weaknesses seen in both Android and iOS, both of the mobile OS are less vulnerable to attack than your PC.
source: Symantec via AndroidandMe