- There remains a global shortage of vaccines to prevent COVID-19 and licensing new vaccines could help fill the gap.
- Researchers identify average antibody levels (called ‘correlates of protection’) required to prevent COVID-19 in populations.
- Correlates of protection could be used to extrapolate efficacy from trials of new vaccines, and could speed development.
Using an analysis based on COVID-19 cases detected in the United Kingdom, and immune system data from the blood samples of volunteers who took part in the UK trials of the Oxford vaccine, the researchers compare antibody levels in vaccine recipients 28 days after their second dose, and COVID-19 cases that occurred more than 7 days after the blood sample was taken.
Writing on MedRxiv, they report that higher levels of anti-spike, anti-RBD IgG, and neutralising antibody titres were associated with a greater degree of protection against COVID-19 – defined as a PCR positive test with at least one symptom present.