Wild – 5 volunteers received the Covid virus directly into their nose – but only 2 of the 5 actually got Covid:

Of the five participants who had been inoculated with Sars-CoV-2, only Mr Goh and one other person were infected.

Five volunteers exposed to Covid-19 virus in Singapore’s first human challenge trial | The Straits Times

What does that mean? Is Covid not as virulent as thought?

Coldstreams