Korean developers of Covid-19 vaccines are struggling to purchase licensed vaccines, which can be compared to their candidate vaccines in comparative immunogenicity trials.

Industry officials said securing comparative vaccines has become a new stumbling block to developing a homegrown Covid-19 vaccine.

In a comparative immunogenicity study, researchers compare the immunogenicity of a vaccine candidate to that of an existing vaccine that had proved safety and efficacy and aimed to prove the candidate’s superiority or non-inferiority to the authorized vaccine. A comparative immunogenicity study can save costs and time compared to a placebo-controlled trial.

Korean developers of Covid-19 vaccines say it is almost impossible to purchase existing Covid-19 vaccines for comparative vaccine trials.
Korean developers of Covid-19 vaccines say it is almost impossible to purchase existing Covid-19 vaccines for comparative vaccine trials.

The health authorities had allowed comparative Covid-19 vaccine trials, given the difficulty recruiting participants amid the rising vaccination rate.

Among the Korean Covid-19 vaccine developers, GeneOne Life Science, EuBiologics, and Cellid, in late-stage trials, said they would compare their vaccine candidates to licensed vaccines.

In Korea, seven companies are working on Covid-19 vaccines – SK Bioscience, Cellid, GeneOne Life Science, Genexine, EuBiologics, Quratis, and inno.N.

GeneOne Life Science and EuBiologics may compare their vaccines to AstraZeneca’s Covid-19 vaccine and Cellid, Janssen’s vaccine, news reports said. Genexine, which plans a global phase 3 study in Indonesia, said the company had no plan to conduct a comparative trial.

On Tuesday, SK Bioscience announced it would enter a phase 3 comparative study of a Covid-19 vaccine candidate, which was for the first time in Korea.

However, other vaccine developers are finding it difficult to purchase a control vaccine.

To conduct a comparative trial, a vaccine developer should talk with an existing vaccine maker to use the current vaccine in the comparative trial.

However, the law prohibits Covid-19 vaccines, purchased by the government and distributed to the people for inoculation, to be used for clinical trials.

SK Bioscience is the only Korean Covid-19 vaccine developer that has secured a comparative vaccine. As a contract manufacturer of the AstraZeneca vaccine, SK Bioscience could find it easier to secure the AZ vaccine in a one-on-one business deal, observers said.

The government actively helped the process, but the two companies’ direct discussion was more effective in securing the AZ vaccine, SK Bioscience said.

The health authorities opened the possibility for comparative studies but do not provide any clear guideline or a support plan to help vaccine developers secure licensed vaccines for comparison.

At a briefing announcing the approval for SK Bioscience’s phase 3 trial of the vaccine candidate GBP510, the Ministry of Food and Drug Safety explained how it helped the company secure the AZ vaccine for comparison.

Food and Drug Safety Minister Kim Gang-lip said helping the company secure the control vaccine was “not an easy task for the government.” To help SK Bioscience, the government made various requests for cooperation to the AZ headquarters or international organizations such as CEPI and the WHO.

However, in the final stage, SK Bioscience’s direct consultation with AZ led to the purchase of the AZ vaccine for comparison, Kim noted.

Kim’s remarks indicated that it would be almost impossible to secure a comparative vaccine without government support, some industry officials said.

Conducting a comparative trial might be “a pipe dream,” some said.

An official at a vaccine developer, when asked whether the company had any plan for a comparative trial, said, “Who will provide us with a control vaccine?”

The official added that it would be nearly impossible to get an authorized vaccine without any external help.

EuBiologics, which had originally planned to use the Novavax vaccine as a comparative vaccine, changed its plan and decided to use the AZ vaccine because of delayed approval for the Novavax vaccine.

EuBiologics is testing EuCorVac-19 in a phase 2 trial and plans to finish the study before Chuseok, the harvest festival that falls on Sept. 21 this year.

“The company is talking with AZ, but it’s indeed difficult to secure a control vaccine. So we need government help,” an official at EuBiologics said.

Cellid, which began a phase 1 study of the Covid-19 vaccine candidate AdCLD-CoV19-1, plans to compare it to the Janssen vaccine. The candidate and the Janssen vaccine are both virus vector vaccines.

“The supply of control vaccines is a concern not only for Cellid but local Covid-19 developers,” said Kang Chang-yul, CEO of Cellid. “Because the government purchases Covid-19 vaccines, there is no route for ordinary companies to get them.”

Kang said that companies that have already developed vaccines find no reason to allow their products to be used for comparative trials because it can increase the number of competitors.

“We are trying to solve this problem at the national level by cooperating with international organizations such as the WHO,” he added.

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