A New Perspective on Summer: Re-examining Taiwan's Medigen Vaccine EUA Path Amid Tzu Chi's Vaccine Fraud Case

In 2021, the Tzu Chi Foundation was defrauded of 1.06 billion NTD in an attempt to procure BNT vaccines. Five years later, with the Taichung District Prosecutors Office concluding its investigation and indicting the defendants, Taiwan is once again being drawn back to the chaotic pandemic year of 2021. At that time, vaccines were in critically short supply, and the government, corporations, and civil groups scrambled to secure supplies. While Tzu Chi’s fraud case warrants internal review of controls and procurement procedures, it should not be used to justify all of Taiwan’s 2021 vaccine policies as correct.

At the same time, Taiwan made another public health decision worthy of re-evaluation five years later: how did the Medigen COVID-19 vaccine, which had not completed traditional large-scale Phase III clinical efficacy trials, obtain emergency use authorization (EUA) from Taiwan’s Food and Drug Administration (TFDA) and enter mass public vaccination programs? Today, Medigen’s COVID-19 vaccine has ceased production. Yet in 2025, former CDC Director Su I-jen wrote in CommonWealth Magazine advocating for a re-evaluation of Medigen’s certification based on real-world data.

EUA Can Be a Lifeline—But Should Not Replace Phase III Validation

Medigen did conduct human trials. Its Phase II clinical trial enrolled over 3,000 participants using a randomized, double-blind, placebo-controlled design, demonstrating the production of neutralizing antibodies and accumulating short-term safety data. The real controversy lies in the fact that when Medigen obtained EUA, it had not completed large-scale Phase III clinical trials involving tens of thousands of participants to directly prove vaccine efficacy through clinical endpoints such as actual infection, hospitalization, severe illness, or death—unlike traditional vaccines.

At the time, Taiwan adopted immunobridging, comparing the neutralizing antibody response generated in Medigen’s Phase II human trials with that of the AstraZeneca (AZ) vaccine, using this as a key basis for EUA efficacy assessment. Academia Sinica院士 Chen Pei-jer publicly questioned this approach in 2021, noting that major international vaccines that had already received EUA had done so only after obtaining short-term efficacy and safety results from Phase III trials.

Chen Chien-wei, Director of the Clinical Trial Center at National Taiwan University Hospital, also pointed out that for domestic vaccines to truly establish international competitiveness, they should still follow international technical guidelines. While BNT and Moderna initially received FDA EUA under emergency conditions, both already had primary efficacy data from large-scale Phase III randomized controlled trials involving tens of thousands of participants. The purpose of EUA is not to skip Phase III trials, but to authorize use based on available evidence during public health emergencies, while continuing post-authorization monitoring.

Novavax Completed the Journey—Why Didn’t Medigen?

Both Medigen and Novavax are protein subunit vaccines. This platform is not a new technology introduced during the COVID-19 era; recombinant hepatitis B vaccines have used it for decades. While their antigen expression methods and adjuvants differ, both use recombinant protein antigens combined with adjuvants to induce immune responses—distinct from the next-generation mRNA vaccine technology used by BNT and Moderna.

Novavax obtained U.S. EUA after completing the PREVENT-19 Phase III clinical trial with approximately 30,000 participants. It continued to supplement safety, efficacy, and manufacturing data, and on May 16, 2025, received full FDA approval. BNT and Moderna also obtained full marketing authorization under the brand names Comirnaty and Spikevax, respectively, with their original EUAs eventually withdrawn. Europe’s AZ vaccine similarly completed large-scale Phase III trials and transitioned from conditional marketing authorization in the EU to standard marketing authorization.

What truly distinguishes Medigen from other major COVID-19 vaccines is the lack of equivalent large-scale Phase III clinical efficacy data at the time of EUA approval—and the failure to transition from emergency authorization to full marketing authorization.

Comparison Table: Phase III Trials, Emergency Authorization, and Full Approval for Major COVID-19 Vaccines

Vaccine | Technology Platform | Large-Scale Phase III Efficacy Trial | Emergency/Conditional Authorization | Subsequent Full Approval ---|---|---|---|--- BNT/Pfizer | mRNA | Yes, ~44,000 participants | U.S. FDA EUA | Comirnaty fully approved; original EUA withdrawn Moderna | mRNA | Yes, ~30,000 participants | U.S. FDA EUA | Spikevax fully approved; original EUA withdrawn AZ/AstraZeneca | Viral Vector | Yes, tens of thousands | EU Conditional Marketing Authorization / WHO EUL | Transitioned to standard EU authorization; later withdrawn due to commercial reasons Novavax | Protein Subunit | Yes, ~30,000 participants | U.S. FDA EUA | Nuvaxovid received full FDA approval in 2025; EUA retired Medigen MVC-COV1901 | Protein Subunit | No equivalent large-scale Phase III efficacy RCT at time of Taiwan EUA | Taiwan Special Approval / EUA | As of March 2026, not listed among Taiwan’s “licensed vaccines”

TFDA Monitored—But Full Approval Was Not Achieved

On July 18, 2021, the Medigen EUA expert review meeting included 21 experts, with the chair not voting. Of the remaining 20, 3 voted in favor, 15 conditionally approved, 1 requested additional documentation, and 1 opposed. The TFDA ultimately required Medigen to continue safety monitoring during special approval manufacturing, submit monthly safety monitoring reports, and provide domestic and international vaccine protection benefit reports within one year of approval.

Medigen did submit the required data. On November 3, 2022, the TFDA convened another expert meeting on Medigen’s vaccine protection benefits, with 15 experts attending. The chair did not vote, and all 14 voting experts agreed that Medigen demonstrated protective benefits against moderate to severe illness and death. This assessment incorporated data submitted by Medigen, hospital database records, and big data from Taiwan’s National Immunization Information Management System and infectious disease reporting systems.

However, the publicly released meeting minutes also noted several limitations. Some experts pointed out that the sample size for the three-dose Medigen group was low; some data were not randomly assigned, introducing selection bias and unmeasurable confounding factors. Others noted that Medigen’s submitted data still had limitations and required further analysis of WHO Phase III trial data. Real-world protection benefits and traditional large-scale randomized controlled Phase III clinical trials are inherently different levels of evidence.

Taiwan’s Own Laws Are Clear

Article 48-2 of the Pharmaceutical Affairs Act stipulates that in response to urgent public health events, the central health authority may specially approve the manufacture or import of specific drugs. The same article also specifies that such special approval may be revoked if a registered drug or suitable alternative therapy becomes available, the public health emergency ends, or safety or efficacy concerns arise.

Article 3 of the Regulations for Special Approval of Manufacturing and Import of Specific Drugs also states that in emergencies, if foreign marketing approval cannot be provided, manufacturers may substitute manufacturing quality data, animal safety testing, human use data, and risk-benefit assessment reports. This system is designed to allow authorities to use special procedures to save time during public health emergencies.

As of March 17, 2026, the TFDA’s COVID-19 special zone lists only two vaccines as “licensed”: Novavax’s recombinant SARS-CoV-2 vaccine and Sinopharm’s COVIran Barekat. Medigen’s MVC-COV1901 is not included. The authorization Medigen received was a special manufacturing approval under Article 48-2 of the Pharmaceutical Affairs Act—not a formal vaccine license obtained after standard registration review.

During the most critical phase of the pandemic, the government had public health justifications for using special approval to address vaccine shortages. But after the pandemic ended, why didn’t the competent authority guide this emergency authorization back onto the normal regulatory track—requiring the manufacturer to complete confirmatory clinical validation, apply for full marketing authorization, and ultimately retire the EUA?

After Three Medigen Doses, Travelers Still Need Booster Shots

Another real-world test for Medigen’s EUA comes from international recognition. In 2022, some countries still required travelers to present vaccination records specifying approved vaccine brands and doses. Medigen was not included on the approved lists of several countries. As a result, Taiwan’s CDC announced on October 19, 2022, that individuals who had received Medigen vaccines and planned to travel abroad could receive one to three additional doses of Taiwan-approved imported COVID-19 vaccines.

This does not prove Medigen lacks protective efficacy, but it does show that Taiwan’s own EUA did not naturally translate into international regulatory or border control recognition. If the government’s policy goal is to support domestic vaccines, success cannot be measured solely by domestic public vaccination rates. It must also include completing full clinical validation, obtaining formal marketing authorization, and even entering international markets.

Citizens who completed three doses of Medigen in Taiwan must still receive additional doses of other vaccines when traveling abroad due to non-recognition of the vaccine brand. This policy cost should not be ignored.

From 30 to 417 NTD—EUA Information Enters the Capital Market

Medigen’s stock price surged from below 30 NTD per share to a high of 417 NTD after the pandemic began. Today, with COVID-19 vaccine production ceased, Medigen (Taiwan Stock Code: 6547) closed at 51.6 NTD on August 7, 2026—nearly 90% below its peak. The stock’s rise and fall alone cannot prove EUA review misconduct, nor can it imply that government vaccine approval was intended to manipulate the stock market.

However, a judicial case did later emerge involving the misuse of material non-public information related to the EUA. The Shilin District Prosecutors Office investigated and found that Liu Tsang-wu, a vaccine expert review committee member of the TFDA, obtained