It says that, broadly, both natural infection and vaccines keep risk low for about 6 months.

该机构称大体来讲，自然感染和疫苗都能在约半年内维持感染低风险。

But getting down to the individual level, there are wide swings in antibody levels after natural infection.

但说到个人，自然感染后的抗体水平的差异幅度很大。

So again we're seeing that antibodies help, this time antibodies that came from the vaccine versus natural infection.

再次，我们可以看到抗体是有帮助的；这一次，抗体来自疫苗而不是感染。

Scientists also do not know how long the body's defenses remain active after a natural infection with the virus.

科学家也不知道人体的免疫机制在自然感染病毒后，能在多长的时间里处于活跃状态。