SARS-CoV-2

In the case of SARS-CoV-2, which has an RNA genome based on adenine, cytosine, guanine and uracil, sometimes mistakes happen.

In other words, while a vaccinated person can still test positive for SARS-CoV-2, the vaccine reduces the chances that they’ll spread the virus to others.

SARS-CoV-2 has already mutated into several worrying new variants, and this process will continue.

Key among them is how well vaccines work to block transmission of SARS-CoV-2, the virus that causes Covid-19.

Janssen’s vaccine targets the spike protein that SARS-CoV-2 uses to attach to and infect human cells, and the variant circulating in South Africa has changed its genetic structure so that it attaches in a slightly different way.