Millions of people have contracted COVID-19 during the pandemic – and scientists are now trying to work out if that will help to make humans immune from catching the virus in the future.

A Singapore study tested SARS patients 17 years after they were originally infected, which is helping scientists to understand more about lasting immunity to SARS-like viruses – including SARS-CoV-2, which causes the disease COVID-19.

Scientists are hoping that their research will find that the body produces antibodies and T-cells after coming into contact with COVID-19, which could protect humans from reinfection for months or even years.

T-cells are a type of white blood cell that have the ability to detect and destroy virus-infected cells. The T-cells also store a memory of the infection, which means they can react quickly if the body is reinfected.

Researchers working on the Singapore study looked at COVID-19 patients and surviving SARS patients and found the T-cell response was just as strong in both groups. It's hoped this discovery will help develop better vaccines.

This is encouraging news after a Spanish study revealed patients suffering mild COVID-19 symptoms may only carry protective antibodies for weeks.