The present application provides methods and compositions for combination therapy with antiviral compounds for the treatment of poxvirus infections, such as orthopox virus infections. In one embodiment, a method of treatment of a poxvirus infection is provided that comprises administering to a host in need thereof cidofovir, cyclic cidofovir, or a salt, ester, or prodrug thereof in combination or alternation with at least a second anti-poxvirus agent. The second anti-poxvirus agent is, for example, a biologic, such as a pegylated interferon.
