Chinese biotechnology company Clover Biopharmaceuticals said the modified version of its Covid-19 vaccine candidate showed a strong immune response against the original strain of the virus and some variants during animal testing.

Clover said in a statement its vaccine candidate demonstrated a “neutralisation” against the South African, Brazilian and UK variants among mice.

The company is testing a Covid-19 vaccine candidate containing an adjuvant, typically designed to boost the efficacy of vaccines, from Dynavax Technologies Corp, Reuters reports.