Clinical Public Health, World Health Organization, Nature Medicine, United Kingdom

Organisations. World Health Organization WHO, Nature Medicine
Period. 14 – 21 July 2020
  • During Monday’s media briefing, the WHO Technical Lead for COVID-19 suggested that while those who are infected with the novel Coronavirus did mount some level of immunity, there are persistent uncertainties how strong that protection is and for long it lasts. This came a day after a study by King’s College London found that immunity appeared to peak three weeks after the first symptoms, waning rapidly thereafter. The study, which is currently under peer review, shows that 60% of people had a “potent” antibody response at the height of their infection, but that only 17% retained the same potency three months later, while others had undetectable antibody levels. This is corroborated by other studies that suggest loss of immunity within a couple months after infection, which if true could challenge the notion of herd immunity to COVID-19.
  • A paper in Nature Medicine this week meanwhile provides a detailed survey of the immune response in a cohort of COVID-19 patients to the Spike antigen by memory B cells and T cells. In addition to coordinating and controlling antibody responses, T cells can also detect fragments of a virus (peptides) which makes it harder to dodge immune defences. Although the study only included a small number of adults with mild infections, both could be detected in the blood one month after COVID-19 infection, suggesting key protective immune responses could be generated in natural infection and may be potentially boosted.
  • These results could have important implications for vaccine development, as certified antibody diagnostic tests are currently designed to detect one single antibody response, and not to quantify it. Consistent and sustained levels of antibody response, however, may require annual booster immunization, similar to the seasonal flu vaccine. According to the Nature Medicine paper, the most effective vaccine against COVID-19 is likely to elicit both neutralizing antibodies, as well as a high total antibody titre and strong T cell response. While immunological questions persist, the WHO warned that it remains possible that people may be re-infected, urging safe public health measures.

This development is part of the digest;