A dosing error made during an AstraZeneca-University of Oxford COVID-19 vaccine trial has led to a new dosage finding in mice, reports a new Northwestern Medicine study.
During the AstraZeneca-Oxford trial, some human participants erroneously received a half dose of their first shot, followed by a full dose for their second shot. Paradoxically, the trial showed that volunteers who got a lower dose of the first shot were better protected against COVID-19 than those who received two full doses.
However, it was not clear if the improvement of the low-dose vaccine was due to the dose itself or the fact that people who received the lower dose had also had a longer time between the first and the second shot, known as an extended prime-boost interval.
Scientists from Northwestern University Feinberg School of Medicine tested the effect of a SARS-CoV-2 vaccine prime dose in mice and found that a lower-dose first shot, followed by a full-dose booster shot, significantly improved the potency of a SARS-CoV-2 vaccine. The booster shot produced more antibodies and T-cells in the mice, allowing them to develop much more robust immune responses against SARS-CoV-2, the study found.
The findings were recently published in the journal Science Immunology.