New Covid-19 Trial Tests Mixing Two Different Vaccines for First Time

LONDON — As the world races to vaccinate and fight new variants of Covid-19, a new trial is trying something that could speed up the process: mixing shots.

Patients taking part in a clinical trial launched Thursday in the United Kingdom will receive different vaccines for their first and second doses: the vaccine developed by Oxford University and AstraZeneca, followed by the one from Pfizer and BioNTech, or vice versa.

The U.K.’s Department of Health said it was the first study of its kind — normally patients receive two doses of the same vaccine — and will help determine the safety of mixing doses across different groups and with a variety of different time intervals.

The researchers said they wanted participants who were over 50 and had not yet been vaccinated to take part in the trial.

The 13-month study, known as “Com-Cov,” is expected to first report initial findings in the summer. Its data could lead to a change in the U.K.’s vaccine policy.

In the U.S., the Centers for Disease Control and Prevention recently changed guidance for Covid-19 vaccines, saying that patients could mix the Moderna and Pfizer doses in “exceptional situations.”

But the Pfizer and Moderna vaccines are both based on the same messenger RNA, or mRNA, platform. The U.K. trial, however, involves mixing vaccines based on different techniques. The AstraZeneca/Oxford vaccine uses an inactivated adenovirus, a type of virus that causes the common cold.

Trial participants will be tested to monitor their levels of antibodies and T cells, which search for and attack infected cells. Read Full Article >