The new H and N surface proteins mean most people do not have antibodies to the virus, allowing it to go pandemic.
新H 和N表面蛋白这意味着多数人对这病毒没有抗体，使其得以流行。
2
The virus only differs from H2N2 in one of its surface proteins, the h; since many people still have antibodies to the unchanged N2 protein, its effects are less severe.
The gene variant associated with the highest B12 levels has previously been determined to protect the stomach from infection by the Norwalk virus and ulcer-causing H. pylori bacterium.