"Our study shows that over time there is a reduction in the proportion of people testing positive for antibodies. It remains unclear what level of immunity antibodies provide, or for how long this immunity lasts."<p>from <a href="https://www.imperial.ac.uk/news/207333/coronavirus-antibody-prevalence-falling-england-react/" rel="nofollow">https://www.imperial.ac.uk/news/207333/coronavirus-antibody-...</a>