A man in Hong Kong caught COVID-19 a second time. Here’s why that’s not surprising (and there’s no need to panic).
This is not necessarily unexpected, because very few natural infections generate an immune response that completely prevents reinfection. Instead, what generally happens after an infection is that the body’s immune response gradually declines over months after the infection is cleared.
Specialised immune cells in the body are tasked with remembering each particular infection, so if you get infected again your body quickly starts producing the relevant antibodies and other immune cells (called T cells) in large numbers. This helps clear the new infection more rapidly and effectively. So you can still get reinfected, but you’re more likely to have fewer symptoms or be asymptomatic.