A electron microscope image of SARS-CoV-2, the virus that causes Covid-19. Photo: EPA
Covid-19 reinfections can be more severe. Should we all worry?
- Covid-19 struck a Nevada man twice, and second time was worse
- Degree of protective immunity after an infection is a great unknown
A electron microscope image of SARS-CoV-2, the virus that causes Covid-19. Photo: EPA
