CORONAVIRUS/Taiwan COVID vaccine maker to apply for EUA after promising Phase II trial results

Taipei, June 10 (CNA) Medigen Vaccine Biologics Corp., a Taiwan-based biopharmaceutical company, said Thursday that it would seek an Emergency Use Authorization (EUA) for its COVID-19 vaccine candidate after its Phase II clinical trials showed promising results. 

At a press conference, the company said trial results for its two-dose recombinant protein vaccine had shown no major safety concerns, as no participants in the study experienced severe adverse reactions. 

Based on the results, Medigen said it would soon submit an EUA application to the FDA, increasing the likelihood the company's jab will become the first Taiwanese COVID-19 vaccine to reach the market.

It would also apply with the European Medicines Agency and other international health authorities to begin Phase III clinical trials as soon as possible, Medigen said. 

According to the guidelines announced by the FDA Friday, domestic COVID-19 vaccines must have a neutralizing antibody potency level equal to or higher than that of the AstraZeneca COVID-19 vaccine in order to be considered for an EUA.

However, because Taiwan's vaccine candidates have not begun larger Phase III trials - which are typically the standard for determining efficacy - the FDA will allow Phase II results to be analyzed via immunobridging, an approach which uses the immune responses measured in clinical trial participants to infer the vaccine's overall level of protection.

According to the FDA, the analysis must be based on samples of serum neutralizing antibodies taken 28 days after participants in a Phase II clinical trial of over 3,000 people received their second vaccine dose.

For the vaccine to be approved, the samples must have a neutralizing antibody geometric mean titer ratio (which refers to antibody concentration) of at least 0.67 and a sero-response rate (which refers to potency of response) of at least 50 percent, the FDA said.

At its press conference, Medigen said the participants in its study had a GMT Titer of 662, a GMT ratio of 163, and a seroconversion rate of 99.8 percent.

Among participants aged 20-64, the GMT Titer rose to 733, the GMT ratio was 180, while the seroconversion rate was 99.9 percent, the company said.

To receive an EUA, Medigen’s trial data will have to be compared to neutralizing antibody potency levels found in a control group of 200 recipients of the AstraZeneca vaccine at a Taoyuan hospital, with a decision coming in July at the earliest, Wu Ming-mei (吳明美), deputy head of the FDA's Medical Products Division, said Thursday. 

Medigen, one of two Taiwanese companies in Phase II trials for a COVID-19 vaccine candidate, has said its recombinant protein vaccine was developed in collaboration with the U.S. National Institutes of Health.

The company began Phase II clinical trials in January at 11 hospitals across Taiwan, with a total of over 4,000 participants, one out of every seven of which was given a placebo. According to Medigen, all participants in the trials received their second dose of the vaccine candidate on April 28 and had a follow-up examination one month later.

The data collected during the trials has been analyzed by a third party research organization, and will be submitted to the FDA with an application for Emergency Use Authorization, according to the company.

When asked whether the vaccine would be recognized abroad, such as by countries using so-called vaccine passports, Medigen CEO Charles Chen (陳燦堅) said the company was hoping to use the same immunobridging approach in international Phase III trials, with the goal of quickly gaining approval from regulators. 

Taiwan's government has signed contracts to purchase 5 million doses of the Medigen vaccine and another 5 million doses from United Biomedical Inc., which is reportedly close to finishing its own Phase II trials.

President Tsai Ing-wen (蔡英文) has promised that doses of a domestic vaccine will start being distributed in July, giving a timely boost to the country's lagging vaccination campaign.

Critics, including a scientist who recently resigned from the government's vaccine review committee in protest, have argued that Tsai's statements on the issue have placed undue political pressure on regulators to approve the vaccines.

Taiwan began its rollout of the first COVID-19 vaccine doses it procured on March 22, and as of Thursday morning, 759,746 doses of the AstraZeneca vaccine had been administered.

The government has also signed contracts to procure nearly 20 million vaccines from abroad, including 5.05 million doses of Moderna, 10 million of AstraZeneca, and 4.76 million of unspecified brands through the COVAX program.