Adenovirus for AZ vaccine, Sinopharm uses inactivated virus

MFDS breaks down COVID-19 vaccine types and mechanisms

RNA and virus vector products already approved, recombinant and DNA vaccines still in development

Diverse types of COVID-19 vaccines are currently in development.

 

Pfizer and Moderna’s vaccine candidates are based on RNA, when AstraZeneca’s is a virus vector and Korean-based SK Bioscience’ is a recombinant vaccine.

 

These types of vaccine have their respective strengths and weaknesses.

 

Some types have been commercialized already, but mRNA vaccine has never been commercialized, making the COVID-19 vaccine the first product.

 

On Jan.

 

7, South Korea’s Ministry of Food and Drug Safety (MFDS) explained about the different types of COVID-19 in development and their mechanisms.

 

The international effort to promptly seek COVID-19 vaccine has pushed pharmaceutical companies to explore a variety of vaccine platform technologies, including virus vector vaccine, mRNA vaccine, recombinant DNA vaccine and inactivated vaccine.

 

#AstraZeneca and Janssen take virus vector vaccine, when Pfizer and Moderna take mRNA vaccine A virus vector vaccine injects adenovirus harmless via virus vector to human body to generate the antigen in the body inducing the adequate immune response.

 

AstraZeneca and Janssen, already signed the procurement deal with South Korea, use the mechanism for their vaccines.

 

The AstraZeneca’s vaccine uses adenovirus that only infects chimpanzees.

 

Compared to mRNA vaccine, the virus vector vaccine is considered to be more stable around heat.

 

But the vaccine type requires cold chain maintained at 4 degrees Celsius as it uses a live adenovirus.

 

So far, Janssen’s Ebola vaccine using the mechanism was the only vaccine approved to market.

 

The U.K.

 

health authority has approved AstraZeneca’s vaccine as of Dec.

 

30, 2020 for an emergency use, whereas European Medicines Agency (EMA) is reportedly conducting an evaluation from October last year.

 

In South Korea, MFDS is currently reviewing the vaccine applied for approval on Jan.

 

4, 2021.

 

Janssen’s (Johnson and Johnson) investigational vaccine is conducting a Phase III clinical trial since September 2020.

 

The vaccine has already requested for evaluation in South Korea (Dec.

 

22, 2020) with the non-clinical and quality relevant evidences.

 

A Korean company Cellid’s candidate vaccine is in process of Phase 1/2 clinical study.

 

In development by Pfizer and Moderna, mRNA vaccine injects antigen gene as a messenger RNA form to generate antigen protein that instigates immune response.

 

The type of vaccine is to be introduced to South Korea later this year.

 

Although the particular vaccine type can be mass produced with fast manufacturing speed, maintaining the stability is extremely difficult with the RNA easily broken down by ribonuclease.

 

Accordingly, the vaccine requires cold chain with temperature kept at around minus 20 degrees Celsius or minus 75 degrees Celsius.

 

And it would be the first time for the type of vaccine to be commercialized.

 

RNA, or ribonucleic acid, is one of two nucleic acids in a cell, which carries genetic information and adjusts genetic expression.

 

Currently, the U.K (Dec.

 

2, 2020), the U.S.

 

(Dec.

 

11, 2020) and Canada (Dec.

 

9, 2020) have granted an emergency approval on Pfizer’s vaccine, whereas Switzerland (Dec.

 

19, 2020) and EU (Dec.

 

21, 2020) have conditionally approved the vaccine use.

 

MFDS elaborated the ministry is positive about the use of Pfizer’s vaccine as it is widely used all around the world, and even the World Health Organization (WHO) also granted approval on the emergency use (Dec.

 

31, 2020).

 

The vaccine has applied for evaluation on its non-clinical and clinical data on Dec.

 

18 last year.

 

Moderna’s vaccine has been approved for emergency use in the U.S.

 

(Dec.

 

18, 2020) and conditionally cleared by EU (Jan.

 

6, 2021).

 

The vaccine has not started the review and approval process in South Korea.

 

From South Korea, Genexine and Gene One Life Science are respectively developing DNA vaccine, similar to the mRNA vaccine.

 

DNA, or deoxyribonucleic acid, is one of two nucleic acids in a cell, which archives and conserves genetic information.

 

Novavax and SK working on recombinant vaccine already used for HBV and HPV vaccine Recombinant vaccine directly injects antigen protein made from recombinant DNA technology to induce immune response, which is one of the most commonly used vaccine platforms.

 

Because the recombinant antigen protein could be insufficient for the full immune response, generally an administration route with vaccine adjuvant is needed.

 

But it is known to be the highly safe vaccine for it has been used throughout the time.

 

Hepatitis B virus vaccine and HPV vaccine use the platform, for instance.

 

Novavax is using the platform for a COVID-19 vaccine with an ongoing Phase III clinical trial started from September last year.

 

Regardless, it has not been approved by any foreign health authority.

 

In South Korea, SK Bioscience is running a Phase 1/2 trial for the vaccine candidate.

 

Inactivated vaccine is a traditional platform of vaccine that triggers immune response by injecting antigen made of killed virus.

 

A number of vaccines are made with the technology.

 

It can be rapidly developed when the infectious virus is collected, and the manufacturing process is comparatively simple and it has an advantage of having outstanding neutralizing antibody.

 

However, for the COVID-19, the vaccine would require a manufacturing facility certified over Biosafety Level 3 (BL3).

 

Biosafety level indicates the level of a facility to safely handle potentially lethal infectious pathogen and depending on the level of the lethal disease, the facility is given a level ranging from BL1 to BL4.

 

Hepatitis A vaccine, injected polio vaccine and Japanese encephalitis vaccine use the inactivated virus platform.

 

A Chinese-based Sinopharm has developed COVID-19 vaccine with the technology green lit for use on July 22, 2020 in China.

 

And according to WHO’s COVID-19 vaccine candidate update report, CanSino Bio (virus vector vaccine) and Gamaleya (virus vector vaccine) are also working on other types of COVID-19 vaccines as well.

 

Considering the public’s heightened interest on COVID-19 vaccine, MFDS stated it would constantly update the vaccine’s efficacy and safety information, and focus on creating an environment for the people to get inoculated with no concern.

 

Moreover, the ministry official added they would do their best for the people to use the safe vaccine by strictly reviewing and managing safety and efficacy of the approved vaccine.