The development of COVID-19 vaccines currently has 4 types, namely whole virus vaccines (live attenuated or inactivated), protein subunits, nucleic (DNA or mRNA), and viral vectors. Understanding the 4 types of COVID-19 vaccines will help doctors provide more appropriate education. Vaccines are one of the main treatments in controlling the spread of SARS-CoV-2. The development of an effective vaccine is an effective means of achieving herd immunity.
There are more than 200 COVID-19 vaccines developed to date. Several conventional vaccines, such as whole viruses, subunit proteins, and viral vectors, have been used to accelerate vaccine development. In vaccines that rely solely on the protein S subunit (spike), it may be necessary to research and redesign the vaccine because of the high mutation rate of protein S in SARS-CoV-2. The ideal vaccine is one that is effective against the target infection, is safe for the general population, and can induce long-term immunity.
Many COVID-19 vaccines continue to be developed today. COVID-19 vaccines can be divided into 4 types, namely whole virus vaccines (live attenuated or inactivated), protein subunits, nucleic (DNA or mRNA), and viral vectors. Each type of vaccine has advantages and disadvantages.
The traditional type of vaccine is the live attenuated vaccine, because it can induce long-term immunogenicity. However, immunodeficient patients may experience reactivation of the virus. Meanwhile, inactivated vaccines are safer to use because of the inability of the virus to replicate in the body. However, for this reason, the long-term immunogenicity of this vaccine is still being questioned.
Another alternative is a type of nucleic acid vaccine, either DNA or RNA. The mRNA vaccine is superior to the DNA vaccine in immunogenicity, but needs to be stored in very cold temperatures below -70°C. Other types of vaccines are protein subunits and viral vectors with questionable long-term immunogenic effects. Further studies are needed to evaluate the efficacy and safety of each type of COVID-19 vaccine.
Some of the WHO-approved COVID-19 vaccines:
- AstraZeneca/Oxford vaccine
- Johnson and Johnson
1. AstraZeneca/Oxford vaccine
The Oxford-AstraZeneca COVID-19 vaccine is a recombinant adenoviral vector vaccine. Quoted from Very Well Health, recombinant vaccines use a small portion of the genetic material of a pathogen, such as SARS-CoV-2, to trigger an immune response.
Certain parts of the virus can be targeted and these vaccines are generally safe to use in large populations of people even those with chronic health problems or people with impaired immunity.
One disadvantage of recombinant adenoviral vector vaccine is that booster injections may be required from time to time.
2. Johnson and Johnson
The data show that immune response resistance in Johnson & Johnson vaccine recipients lasts for at least 8 months, providing protection from infection with the Delta variant of Covid-19. The company also said its vaccine was 85 percent effective and could also help prevent hospitalizations and deaths. According to the World Health Organization (WHO), the Delta variant was first identified in India as the globally dominant variant of the coronavirus.
Moderna's type of COVID-19 vaccine uses messenger RNA (mRNA). The coronavirus has a spike-like structure on its surface called the S protein. The COVID-19 mRNA vaccine gives cells instructions on how to make the harmless part of the S protein.
After vaccination, cells begin to make protein fragments and display them on the cell surface. The immune system will recognize that the protein is not there and begin to build an immune response and make antibodies.
This type of COVID-19 vaccine is for people aged 18 years and over. The vaccine requires two injections given 28 days apart.
The United States Centers for Disease Control and Prevention (CDC) describes several criteria for people who cannot receive the Moderna vaccine. The following are the criteria for people who are not recommended to get the Moderna COVID-19 vaccine, quoted from the official CDC website.
- People who have had a severe allergic reaction (anaphylaxis) or an immediate even if not severe allergic reaction to any ingredient in the COVID-19 mRNA vaccine.
- People who have experienced a severe allergic reaction (anaphylaxis) or an immediate allergic reaction that is not even severe after getting the first dose of the vaccine.
- Immediate allergic reaction means a reaction within 4 hours of being vaccinated, including symptoms such as hives, swelling, or wheezing (breathing problems).
- Allergic reactions to polyethylene glycol (PEG) and polysorbates. Polysorbate is not an ingredient in the COVID-19 mRNA vaccine but is closely related to PEG, which is in the vaccine. People who are allergic to PEG or polysorbate should not get the COVID-19 mRNA vaccine.
Pfizer-BioNTech's COVID-19 axin is named BNT162b2 and is based on messenger RNA (mRNA) technology. This vaccine uses a synthetic gene that is easier to create, so it can be produced faster than conventional technology.
This dormant virus does not cause illness but teaches the immune system to respond to resistance. With mRNA, the body is not injected with dead or weakened viruses, but the genetic code of the virus is injected. As a result, the body will produce proteins that stimulate an immune response.
The CDC says Pfizer-BioNTech's type of COVID-19 vaccine is recommended for people 16 years of age and older. Just like the Moderna COVID-19 vaccine, the CDC also provides a number of criteria for people who are not advised to receive the same Pfizer vaccine as the Moderna vaccine.
The Sinopharm vaccine is a coronavirus vaccine made in China and has been tested in several other countries.
The vaccine has been included in the WHO Covid-19 vaccine list and received an Emergency Use Authorization (EUA) in China, the United Arab Emirates, Bahrain, Egypt and Jordan, and now also in Indonesia. This vaccine uses the same platform as the Sinovac vaccine, namely the inactivated virus or inactivated vaccine type
According to the World Health Organization (WHO), inactivated vaccines are vaccines that use inactivated viral particles to expose the immune system to viruses, without risking a serious disease response. The Sinopharm vaccine is also the first vaccine to be equipped with a temperature monitor on the vaccine bottle. A small sticker on the vaccine bottle changes color when the vaccine is exposed to heat, and tells health care workers whether the vaccine can be used safely. In clinical trials in the United Arab Emirates, the efficacy of this Chinese-made vaccine reached 78 percent, and this vaccine can be used in the population aged 18 years and over to the elderly (elderly).
Sinovac's type of COVID-19 vaccine works to strengthen the immune system so that antibodies can fight the Corona virus. This vaccine is made using an inactivated virus platform or method.
In this way, the body can learn to recognize the virus that causes COVID-19, SARS-CoV-2, without having to face the risk of serious infection. The vaccine is given in two doses or requires two injections.