4.3. Chance of re-infection
The main conundrum is whether primary COVID-19 infection prevents the
second infection and how long the patient is immune. Unfortunately,
affliction to COVID-19 does not appeared to prevent further infection,
especially for a long time. This finding most likely reduces the success
of vaccine candidates. Furthermore, studies suggest that there are
genetically distinct strains of the SARS-CoV2 in communities where
infection with one does not confer full immunity against the others. The
finding was made in a case study by Tillett et al. that the infection
occurred with two genetically distinct SARS-CoV2 strains which did not
appear to have occurred naturally during evolutionary mechanisms in the
human host shortly [32].