Medigen Vaccine Biologics Corp. announced the highly-anticipated results of a Phase II COVID-19 vaccine trial on June 10. The company says the data shows that the vaccine is safe and likely to be effective at preventing the disease. But experts say we should wait for more data.
After news of a successful Phase II trial last week, hopes are high for a Taiwan-made COVID-19 vaccine. But doctors are urging caution. Taipei Medical University Hospital’s Doctor Chou Pai-chien says it’s still unclear whether the Medigen vaccine’s dosage might be a little too high, like other vaccines. He says he would also be disappointed if it is only as effective as the AstraZeneca vaccine.
The Medigen vaccine has not completed Phase III trials. But Taiwan’s former Vice-President Chen Chien-jen says that you can use “immunobridging” to determine a vaccine’s effectiveness. He says many countries’ vaccines have not completed Phase III trials. But during Phase II, tests can show whether people who take the vaccine create enough antibodies to protect against the virus.
Medigen says its vaccine had a neutralizing antibody titer of 662. That’s almost double the numbers reported by AstraZeneca and Moderna. But experts say you cannot compare them, because their laboratories use different testing methods. We’ll only know how Medigen’s vaccine compares to AstraZeneca’s when medical authorities publish their research data at the end of June.
Shih Hsin-ju is director of the Research Center for Emerging Viral Infections at Chang Gung University. She says immunobridging has its drawbacks. Shih says if the vaccine’s authorization comes down to a single lab’s results, that might give people doubts about the true effectiveness of the vaccine.
It’ll still be a while before experts are convinced by Medigen’s results. They say relying on immunobridging is far from ideal. For now, we can only wait for a clearer picture when fuller results are available at the end of June.