National Taiwan University Hospital is recruiting subjects for its vaccine mixing trial. It''s already filled half its participant groups, but it still needs subjects who received the domestically made Medigen vaccine. A hospital doctor said the study has been underway for about half a year. The goal is to find out which vaccine combinations induce the most potent protective effect.

So far 722,000 people have received a dose of the Medigen COVID vaccine. Now second doses are rolling out, although the brand’s protective efficacy remains unknown. Lee Ping-ing, a physician at NTU Hospital, put out a call to people who want to know their antibody level. On social media, he wrote that eligible Medigen recipients 20 and older should join his hospital’s human trial, in which they’ll get antibody tests for free.

Lee Ping-ing
NTU Hospital physician
This has been underway for almost half a year now. Its goal is to find out just what the antibody levels are for people in Taiwan who received the vaccine. We can use the figures to make comparisons with the antibody reactions induced by other vaccines, to see whether one is high or low. We can also look at reactions induced in T cells.

The trial has four groups of participants, who received the regimens of Medigen-Medigen, Medigen-Pfizer, AstraZeneca-Moderna, and AstraZeneca-Pfizer. The trial will compare the changes seen in the neutralizing antibodies of the four groups. Every group will comprise about 200 subjects who take seven blood tests, over a maximum follow-up period of 18 months. Over the last half year, researchers have filled the mixed AstraZeneca groups. Recruitment is still on for subjects who received Medigen.

With vaccine mixing on the rise, Lee was asked about the possibilities for those who’d had one dose of Sinovac or Sinopharm in China. He said these people can receive a second dose of any brand approved in Taiwan.

Lee Ping-ing
NTU Hospital physician
It’s a bit of a vexing issue. We can’t really say that those vaccines are entirely ineffective. But we also can’t monitor the effect it’s having on you. We will allow you to choose a vaccine brand that’s already been approved domestically. That way, you can have more of a guarantee that there’s a better protective effect.

Huang Li-min
NTU Children’s Hospital superintendent
If you’re going to mix and match, the current recommendation is to get an mRNA vaccine. That’s the safest approach. Because U.K. data has shown that no matter what vaccine you get as your first dose, if you get a second or third dose of an mRNA vaccine, there will be a fairly good protective effect.

The CECC said that nationals who received one dose of a Chinese vaccine are eligible for a Taiwan-approved brand four weeks later. After returning to Taiwan, they should register online for their chosen vaccine brand and wait to be called up in order of age.