What is the COVID-19 vaccine?

It refers to a vaccine developed to prevent COVID-19 that has spread worldwide in 2020 and has led to a long-term pandemic. As of the end of February 2021, AstraZeneca (UK), Pfizer (US/Germany), Janssen (US), Moderna (US), Novavex (US), Sputnik V of Russia, and Sinoparm/Sino of China A bag has been developed and inoculated or is scheduled to be inoculated. Storage temperature, inoculation interval, inoculation frequency, storage and distribution, etc., differ according to the type of vaccine.

It refers to a vaccine developed to prevent COVID-19 that has spread worldwide in 2020 and has led to a long-term pandemic (the highest warning rating for infectious diseases proclaimed by the World Health Organization (WHO), a state in which infectious diseases are pandemic worldwide). Currently, AstraZeneca (UK), Pfizer (US/Germany), Janssen (US), Moderna (US), Novavex (US), Sputnik V in Russia, and Sinoparm/Sinobag in China have been developed and inoculated. Has been completed or an inoculation is scheduled to be made. Such vaccines differ in storage temperature, inoculation interval, inoculation frequency, storage and distribution, etc., depending on the type of vaccine.

1. The principle of prevention of vaccines

Vaccines are intended to activate the human body’s immune system by injecting artificially attenuated pathogens into the human body before infection with pathogens, thereby preventing or minimizing the damage that the human body will infect with pathogens in the future. In other words, it is not pathogenic, but when an antigen for a specific pathogen is injected into the human body, the body’s immune cells form antibodies and prevent diseases by making them immune to viruses.

When you receive the COVID-19 vaccine, the antigen components of the vaccine that have entered the human body stimulate immune cells (a type of lymphocyte belonging to B cells and white blood cells that produce antibodies). And the B cells that are stimulated in this way produce neutralizing antibodies that can remove the virus and store them in the human body. This is the principle of removing the virus if the COVID-19 virus invades from the outside through the respiratory tract.

Summary of COVID-19 Vaccine Principles

  1. Injection of the COVID-19 vaccine
  2. Antigen components of vaccines that have entered the human body stimulate immune cells (B cells)
  3. Make neutralizing antibodies that can remove viruses from stimulated B cells and store them in the body.
  4. When the COVID-19 virus invades through the respiratory tract, neutralizing antibodies in the body remove the invading COVID-19 virus.

2. Types according to vaccine platform


The COVID-19 vaccines developed to date are divided into, viral vector vaccine, inactivated vaccine, DNA vaccine, RNA vaccine, recombinant vaccine, virus-like particle vaccine, etc., depending on the vaccine platform. Here, the โ€œvaccine platformโ€ is a base technology for developing vaccines by changing only specific antigens or genetic information in the vaccine, and if this is used, the vaccine development period can be significantly shortened.

Representatively, the currently developed vaccines are classified according to the developer as follows., Messenger ribonucleic acid (mRNA) Pfizer vaccine and Moderna vaccine, Viral vector type AstraZeneca vaccine, Janssen vaccine, Sputnik V, Recombinant NovaVax vaccine, Inactivated Synopam and Synovac vaccine (China)

a. Messenger ribonucleic acid (mRNA) vaccine

It is a vaccine that utilizes messenger ribonucleic acid (mRNA) containing the genetic information of the virus. Here, RNA is one of the nucleic acids in the nucleus of cells that mediate gene information to regulate gene expression. Unlike conventional vaccines that use weakened viruses or viral proteins, mRNA containing the virus’s genetic information is injected to create protein spikes in the body in advance, which are bullhorn-shaped projections surrounding the COVID-19 virus, thereby generating immunity. to be. The advantage of mRNA vaccines is that the design and production period is short if only the genetic information of the virus is known. Among the COVID-19 vaccines, there are Pfizer and Modena vaccines that utilize mRNA.

1) Pfizer vaccine

It is a vaccine jointly developed by Pfizer in the United States and Biotech in Germany, and requires a cryogenic refrigeration system due to difficult storage and distribution conditions. It can be distributed and stored for 6 months at -60~90โ„ƒ, but the period of distribution at 2~8โ„ƒ is only 5 days. The number of vaccinations is 2 times and the vaccination interval is 21 days.

2) Moderna vaccine

It is a vaccine developed by Moderna of the United States, and requires a total of 2 vaccinations, and the vaccination interval is 28 days. It is difficult to store due to the nature of the mRNA vaccine, but it is better than Pfizer.

b. Virus vector vaccine

Viral vector vaccine is a method of administering a virus antigen gene into another virus. The COVID-19 virus surface antigen gene is cultured and produced by putting the COVID-19 virus surface antigen gene into an adenovirus that only infects chimpanzees, and then delivered into human cells. The delivered COVID-19 antigen gene induces the production of neutralizing antibodies that neutralize the COVID-19 virus by synthesizing antigenic proteins in the body. Viral vector vaccines are relatively stable to heat compared to RNA vaccines, but since they use live adenovirus, they require a cold chain equivalent to live vaccines (4โ„ƒ). Representative viral vector vaccines include AstraZeneca vaccine, Janssen vaccine, and Sputnik V.

1) AstraZeneca vaccine

It is a vaccine developed by AstraZeneca, UK. The number of vaccinations is 2 and the vaccination interval is 28 days. AstraZeneca vaccine can be stored and distributed for 6 months from the date of manufacture at 2-8โ„ƒ in an unopened state. After opening, it can be stored for 6 hours cumulatively at room temperature and 48 hours in a refrigerated state. However, for safe vaccination, the same-day opening vaccine should be used on the same day.

2) Janssen vaccine

It is a vaccine developed by Janssen, a subsidiary of Johnson & Johnson in the United States, and unlike other vaccines, it is provided as a single vaccination. In addition, it can be distributed and stored for 3 months at 2-8โ„ƒ, not at cryogenic temperatures, and up to 24 months at -20โ„ƒ.

3) Sputnik V vaccine

It is a COVID-19 vaccine developed by the National Institute of Infectious Diseases and Microbiology under the Ministry of Health of Russia, and it is known that it can be refrigerated at 2 to 8 degrees Celsius when stored as a powder and can be stored for 6 months at -18 degrees Celsius. Russia approved Sputnik V for the first time in the world in August 2020. Unlike the usual vaccine development procedure, it was approved immediately after phases 1 and 2 before phase 3 clinical trials (Phase 3), causing controversy about efficacy and safety.

c. Recombinant vaccine

It induces an immune response by injecting an antigenic protein made using genetic recombination technology into the human body, and is one of the most used vaccine platforms. Recombinant antigen protein alone may have a low immune response, so a formulation containing an adjuvant (aluminum salt, etc.) is generally required, and it is known as a vaccine with high safety due to long-term use. This product is based on the recombinant method used to develop the existing hepatitis B vaccine and human papillomavirus (HPV) vaccine, and the NovaVax vaccine corresponds to the COVID-19 vaccine.

1) NovaVax vaccine

It is a vaccine developed by NovaVax in the United States. The number of vaccinations is 2 times and the vaccination interval is 21 days. It can be stored and distributed under conditions of 2-8โ„ƒ, so it can be transported to the existing system.

d. Inactivated vaccine

It is a traditional vaccine platform that removes the pathogenicity of the virus, injects it into the human body, and induces an immune response. When securing infectious virus, rapid development is possible, manufacturing method is simple, and neutralizing antibody induction is excellent, but for COVID-19 virus, BL3 level (Biosafety level, BL): The level of shielding required to safely handle infectious pathogens It means that production facilities of BL1 to BL4 are required according to the level of risk. Inactivated vaccines include hepatitis A, injectable polio, and Japanese encephalitis, and COVID-19 vaccines include China’s Sinopam and Sinobac vaccines. It is known that synoparm and synovac vaccine can be stored at 2 to 8 degrees Celsius, which is similar to a typical refrigerator temperature.

DNA vaccine It is a vaccine that induces an immune response by injecting a part of DNA, not a virus, directly into the human body. That is, some genes such as pathogens and viruses are artificially duplicated and then injected into the muscle to cause an immune response. Although the antigen of the pathogen was not administered directly, it produces the same effect as administered by biosynthesizing within cells using genetic material. DNA vaccines can be stored for several months or longer even at room temperature, but the disadvantage is that the administered individual produces less antigen and has low immune response and preventive effect.

3. Frequently Asked Questions About COVID-19 Vaccination

Q. How long does it take to obtain immunity after vaccination?

A. In general, it takes about 2 weeks for the protective antibody to form after vaccination. In the case of COVID-19 vaccine, it is reported that the antibody is highest 7-14 days after the second vaccination, and it is very important to complete the 2nd vaccination within the recommended period for each vaccine for maximum vaccination effect.

Q. Do people with asymptomatic infections or those who have been infected in the past also need vaccination?

A. You can be vaccinated regardless of your asymptomatic infection or COVID-19 infection history, and you do not need to undergo a diagnostic test before vaccination to determine if you are vaccinated.

Q. Can I get COVID-19 from getting the vaccine?

A. Because vaccination does not form 100% immunity, you can become infected with COVID-19 if immunity is not formed after vaccination, before immunity is formed, or if the effect of the immunity formed is diminished over time. Therefore, even if you have been vaccinated, you must follow the quarantine rules such as wearing a mask, washing your hands, and keeping your distance away.

Q. Is it possible to get the COVID-19 vaccine and other vaccines at the same time?

A. When concurrent vaccination with other vaccines, data on the safety and efficacy of the COVID-19 vaccine are insufficient, so it is recommended to inoculate alone. It is recommended to maintain an interval of at least 14 days before and after vaccination with other vaccines. If the COVID-19 vaccine is inadvertently vaccinated with other vaccines or within 14 days, additional vaccination is not recommended.

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