This only works against RNA viruses. DNA virus genes might be more difficult to silence. 2 years is what they need for SARS-CoV-2. But it will depend on the incentive if they redevelop it for other viruses. Many viruses integrate their genome into the cell genome. Even SARS-CoV-2 integrates itself into the DNA even though it is an RNA virus. Reversing existing mutations is more difficult. It might become an antiviral for acute infections, but latent infections are a different nut to crack.