Why do some get infected twice and others are spared from corona? | medical

Just under 23,000 Belgians – both vaccinated and unvaccinated – became infected with the corona virus again in the past eight weeks, after contracting it earlier. This is apparent from a new report from health institute Sciensano, although it only concerns people who have had themselves tested effectively. How did that happen? Do some naturally have weaker immune systems? Virologist Marc Van Ranst explains.