@DouglasDodson @MathStuart @hjelle_brian There are hundreds of circulating cold viruses. You could be fully immune to each one you catch (not what happens, but this is hypothetical) and still get colds year after year.
@DouglasDodson@MathStuart@hjelle_brian有数百种流行感冒病毒。你可能对每一次感冒都完全免疫（不是发生了什么，但这是假设），并且仍然年复一年地感冒。