COVID 19 Vaccination

Overview

Vaccination is the process of administration of a vaccine into the body to build immunity against a particular disease. Currently, the safest way to combat COVID 19 is vaccination. On January 11 2020, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) genetic sequence was published. This provoked a series of investigations and collaborations among biopharmaceutical manufacturers and scientists. Various COVID vaccines were developed and their clinical trials began. There are now several vaccines available for COVID 19.

Which vaccines are currently available for COVID 19?

The vaccines approved by the World Health Organization (WHO) for its Emergency Use Listing (EUI) are Pfizer/BioNtech, SII/Covishield, AstraZeneca, Johnson & Johnson’s Janssen, Moderna, and Sinopharm vaccines.

What are the different types of Covid 19 vaccines?

There are four types of vaccines currently being used in clinical trials:

  1. Whole virus
  2. Protein subunit
  3. Viral vector
  4. Nucleic acid (DNA and RNA)

How do different vaccines work?

Ø  AstraZeneca/Oxford COVID 19 vaccine:

To make the vaccine, the Oxford-AstraZeneca team incorporated the gene that codes for the coronavirus spike protein into the chimpanzee adenovirus. This virus enters the host cells but cannot replicate inside them. When the vaccine is injected into the patient, the adenovirus enters the host cell. Once inside the host cell, the virus directs it to read the gene for coronavirus spike protein and copy it into a molecule called messenger RNA or mRNA. The mRNA is then translated into spike proteins that show up on the surface of host cells. This triggers the immune system of our body. The immune system activates T-cells and produces antibodies to eliminate the cells with the spike protein. If a person later gets infected with the coronavirus, T-cells and antibodies are activated to eliminate the virus. AstraZeneca vaccine is administered in a 2-dose series, given 28 days apart.

Ø  Covishield COVID 19 vaccine:

The Covishield COVID 19 vaccine is currently being manufactured by the Serum Institute of India (SII). This vaccine works on the AstraZeneca-Oxford Model.

The genetic material is inserted into the chimpanzee adenovirus. The chimpanzee adenovirus is used because humans do not have pre-existing antibodies to this virus. When the vaccine is injected into humans, it stimulates the immunity system of our body to start making T-cells and antibodies. These antibodies and T-cells provide immunity against further coronavirus infections. The Covishield is given in a 2-dose series 12 days apart.

Covishield usually causes mild side effects such as headache, pain at the injection site, joint pain (arthralgia), etc.

Ø  Covaxin COVID 19 Vaccine:

Covaxin COVID 19 vaccine is developed by an Indian company, Bharat Biotech, in collaboration with the Indian Council of Medical Research, Delhi (ICMR) and the National Institute of Virology, Pune (NIV). Covaxin is an inactivated vaccine. To make the vaccine, the scientists weakened the coronavirus so that it can no longer replicate inside host cells. The researchers then mixed the vaccine with a compound called adjuvant. Adjuvants boost the response of our immunity system to the vaccine. When the vaccine is administered, the immune system recognizes the dead virus and makes antibodies to eliminate that virus. Covaxin is administered in a 2-dose series, given four weeks apart.

The side effects of Covaxin are usually mild such as pain and swelling at the injection site, fever, weakness, and body pain, etc.

Ø  Sputnik V COVID 19 Vaccine:

The Sputnik V COVID 19 vaccine is also an adenoviral vaccine developed by the Gamaleya Research Institute of Epidemiology and Microbiology, Moscow. The vaccine uses a combination of 2 genetically modified human adenoviruses (Ad26 and Ad5) that are unable to invade and infect host cells. The gene for the coronavirus spike protein is then added to the harmless adenovirus. When the vaccine is inoculated into human body, it activates our immune system. The immune system starts making antibodies to eliminate the virus. Memory cells are formed that protect the human body from later coronavirus infections.

The most common side effects of this vaccine are fatigue, flu-like illness, pain and swelling at the injection site, etc.

Ø  Pfizer/BioNtech and Moderna COVID 19 vaccines:

Pfizer and Moderna vaccines are mRNA vaccines. After injection, the mRNA vaccine enters the host cell and instructs it to make specific proteins (coronavirus spike proteins). These proteins are expressed on the surface of host cells and trigger an immune response. T-cells and antibodies are generated that protect us from further infections.

Ø  Johnson and Johnson’s Janssen COVID 19 vaccine:

Like AstraZeneca/Oxford vaccine, the Janssen vaccine works by introducing a genetically modified harmless virus (human adenovirus) into the body. However, this vaccine requires one shot, rather than two shots of AstraZeneca, for being fully vaccinated.

Ø  Sinopharm COVID 19 Vaccine:

Sinopharm COVID 19 vaccine was developed by the Beijing Institute of Biological Products in early 2020. Sinopharm is an inactivated vaccine. It consists of dead viruses that are unable to cause the disease. When injected into the body, the inactivated viruses trigger an immune response. The immune system produces antibodies that protect our body from the actual virus.

Conclusion:

Covid vaccination may be the best step to prevent Covid spread. But it is equally important to understand that there are a lot of post covid symptoms including different types of pain in post covid stage.

References

https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines.html

https://www.who.int/news-room/q-a-detail/vaccines-and-immunization-what-is-vaccination?adgroupsurvey={adgroupsurvey}&gclid=Cj0KCQjwna2FBhDPARIsACAEc_Vxbu9hkE9lQsc0YUYxaZFeymRYwJ4CJqLDCbgJkADD2BQOBwOITckaAndBEALw_wcB

https://www.nytimes.com/interactive/2020/health/oxford-astrazeneca-covid-19-vaccine.html

https://www.bbc.com/news/world-asia-india-55748124