COVID-19 vaccines: What you need to know?

By :  Ms Thiviyamalar Tanggavelu, Pharmacist KPJ Penang. 

Example of COVID-19 Vaccine

Vaccines work by imitating infectious agents such as viruses, bacteria or other microorganisms which can cause diseases. Conventionally, vaccines are made by introducing a weakened form of an infectious agent that allows the immune system to build a memory of it. By this, the immune system will recognize the pathogens and fight back before a person gets infected.

Each type of vaccine for COVID-19 acts differently to introduce antigens, which are specific features of the SARS-CoV-2 virus, to your body. The antigen activates a specific immune response and this response builds immune memory, so the body can fight off SARS-CoV-2 in future.

Types of Vaccines:

• Inactivated vaccines contain killed SARS-CoV-2 virus. The killed virus is recognized by the immune response to trigger a response without causing illness. This response builds immune memory so the body can fight off SARS-CoV-2 in future.
• Example of vaccines in clinical trials: Sinovac and Sinopharm.

• Attenuated vaccines contain weakened SARS-CoV-2 virus. The weakened virus is by the immune system to trigger a response without causing illness.
• Example of vaccine in clinical trials for Covid-19: Codagenix.

• Nucleic-acid vaccines contain a segment SARS-CoV-2 virus genetic materials that codes for a specific protein. It can be DNA or RNA. The body cells use the genetic materials to make the  SARS-CoV-2 protein, which is recognised by the immune system to produce the response. 
• Example of vaccine in use for Covid-19: Moderna, Pfizer and BioNtech.

• Protein vaccines use proteins from SARS-CoV-2 virus which is recognised by the immune system to produce a response. The proteins can be whole proteins, protein fragments or many protein molecules packed into nanoparticles.
•  Example of the vaccine in clinical trials for Covid-19: Novavax.

• Viral vector vaccines use an unrelated harmless virus, modified SARS-CoV-2. The delivery virus is known as a viral vector. 
• Example of vaccines in clinical trials: Janseen, Cansino, and Gamaleya.

Who to get vaccinated first?

Since the supply of Covid-19 vaccines are limited, the Centers for Disease Control and Prevention (CDC) makes some recommendation on who should get vaccinated first based on: 

●       Decrease death and serious disease as much as possible.

●       Preserve the functioning of society.

●      Reduce the extra burden COVID-19 was having on people already facing disparities.

Based on the recommendation, Malaysia’s first phase of Covid-19 Immunisation Plan will cover 80% of the population. 

The first phase will prioritize mainly frontliners about 500,000 security and healthcare workers and expected to end by  April 2021. The second phase of vaccination will involve senior citizens, people with chronic illnesses and disabled who can expect to receive their vaccinations by the second quarter of the year 2021. 

The remaining population who are healthy adults above 18 years old can expect their turn by the third quarter of the year 2021 or later. The third phase is considered crucial as it will build herd immunity among the population. 

Do vaccines work?

• Based on clinical trials, the first two vaccines were shown to be extremely effective at preventing COVID-19: Pfizer (95%) and Moderna (95%).

• The trials so far show the vaccines are equally effective across age, gender, race and ethnicity subgroups.

• The clinical trials were conducted with a diverse group of participants, including people of Asian, Black, Hispanic/Latin and Native American descent.

How about your second shot?

Both COVID-19 mRNA (e.g. Pfizer and Moderna) vaccines will require two shots to get the most protection. The timing between the first and second shot depends on the type of vaccine that has been received. You should receive your second shot for:

●        Pfizer-BioNTech 3 weeks or 21 days after your first shot.

●        Moderna 1 month or 28 days after your first shot.

A person should get a second shot as close to the recommended or 1-month or 3-weeks interval as possible. However, there is no maximum interval between the first and second doses of either vaccine. At the same time, a person should not get the vaccine before or later than the recommended period to maintain the efficacy of the vaccine.

Dispelling myths about Covid-19 vaccine

●         A person won't get Covid-19 from its vaccine.

●         The vaccine won't alter the genetic material of a person.

●         Even if a person is vaccinated, he or she should take necessary safety precautions such as wearing a face mask, frequently washing hands and maintaining physical distancing.

References

1. Coronavirus Disease 2019 (COVID-19). Centers for Disease Control and Prevention. (2021). Retrieved 3 February 2021, from https://www.cdc.gov /coronavirus/2019-ncov/index.html.
2. COVID-19 Vaccines: Infographic. https://www.hopkinsmedicine.org /health/conditions-and-diseases/coronavirus/coronavirus-vaccines-infographic. (2021). Retrieved 3 February 2021, from https://www.hopkinsmedicine.org /health/conditions-and-diseases/coronavirus/coronavirus-vaccines-infographic.
3. COVID-19 Malaysia. 2021. COVID-19 Malaysia Updates. [online] Available at:<http://covid-19.moh.gov.my/semasa-kkm/2021/feb/proses-agihan-vaksin-05022021> [Accessed 7 February 2021].
4. Types of vaccines for COVID-19 | British Society for Immunology. Immunology.org. (2021). Retrieved 3 February 2021, from https://www. immunology.org/coronavirus/connect-coronavirus-public-engagement-resources/types-vaccines-for-covid-19.

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