How do viral vectors compare to other approaches in terms of efficacy?

The innate characteristics of viruses translates to superior gene delivery and expression efficiency versus non-viral methods such as lipofection and sonoporation.1,2 Moreover, viral vectors provide longer and more stable gene expression durations compared to non-viral approaches.1,2 However, viral vectors encounter additional concerns not present in non-viral vector methods, such as immunogenicity, immune memory development, and inflammation.1,2

References:
1. M.S. Al-Dosari and X. Gao, “Nonviral Gene Delivery: Principle, Limitations, and Recent Progress,” AAPS J 11(4): 671, 2009.
2. I.M. Verma and N.B. Somia, “Gene therapy -- promises, problems and prospects,” Nature 389(6648): 239-242, 1997.