Key '2009' study by Callow et al.: "The time course of the immune response to experimental coronavirus infection of man"; showed the course after persons inoculated with coronavirus 229E'

This one study holds many answers to what happens: "Detailed changes in the concentration of specific circulating and local antibodies were followed in 15 volunteers inoculated with coronavirus 229E"

Key phrase:

‘In this group, antibody concentrations started to increase 1 week after inoculation and reached a maximum about 1 week later. Thereafter antibody titres slowly declined. Although concentrations were still slightly raised 1 year later, this did not always prevent reinfection when volunteers were then challenged with the homologous virus. However, the period of virus shedding was shorter than before and none developed a cold. All of the uninfected group were infected on re-challenge although they also appeared to show some resistance to disease and in the extent of infection.’

This one simple elegant study shows us what natural immunity is, how a prior coronavirus infection confers protection in terms of re-infection and also disease.

SOURCE:

https://www.cambridge.org/core/journals/epidemiology-and-infection/article/time-course-of-the-immune-response-to-experimental-coronavirus-infection-of-man/6C633E4EFDAEB2B4C0E39861A9F88B01