Merck sought to impeach Wyeth's composition and formulation patents relating to the Prevnar 13 pneumococcal conjugate vaccine.
The Court found that the composition patent claims were valid but limited to 13 serotypes, as the invention was neither anticipated nor obvious given the complexities of conjugation and immune interference.
However, the Court invalidated the formulation patents, finding that the use of surfactants, buffers, and aluminum salts to stabilize formulations in siliconized containers was obvious in light of prior art, and the specific 13-valent claims were invalid for obviousness-type double patenting.