Antibody and immune responses to SARS-CoV-2, the virus that causes COVID-19, varied substantially among convalescing patients, a small study found.

The plasma of 41 patients in Australia recovering from COVID-19 showed antibodies, memory B cells, and circulating follicular helper T cells against the SARS-CoV-2 spike glycoprotein, but there was a range of certain B and T cell responses and frequency among individuals, reported Stephen Kent, PhD, of the University of Melbourne in Australia, and colleagues, writing in Nature Medicine.

Why is this important for vaccine development? Because, Kent’s group said, “neutralization activity in the plasma ranges widely” despite the qualitative detection of major immune response markers.

Limitations to the study include its small sample size and lack of epitope-level resolution. However, Kent’s group suggested their research could be a step towards developing biomarkers of immune function, specifically B cell and circulating follicular helper T cell frequencies and phenotypes, for clinical trials of new vaccines targeting the viral spike protein.