INTRODUCTION:

The first mass vaccination programme started in December 2020 with 13 different vaccines.On 31^st December 2020 WHO Emergency Use Listing (EUL) had given approval for Pfizer/BioNtech Comirnaty vaccine.

On16^th February WHO Emergency Use Listing (EUL) had given approval for SII/Covishield and AstraZeneca/AZD1222 vaccines (developed by AstraZeneca/ Oxford and manufactured by the State Institute of India and SK Bio respectively). On 12^th March 2021 WHO Emergency Use Listing (EUL) had given approval for Janssen/Ad26.COV 2.S developed by Johnson and Johnson. On 30^th April 2021WHO Emergency Use Listing (EUL) had given approval for Moderna COVID-19 vaccine (mRNA 1273) and on 7^th May 2021 WHO Emergency Use Listing (EUL) had given approval for the Sinopharm COVID-19 vaccine, produced by Beijing Bio-Institute of Biological Products Co Ltd, subsidiary of China National Biotec Group (CNBG)¹

The impact of COVID-19 vaccines on the pandemic situation depends on several factors, which include the effectiveness of the vaccines; time for their approval, manufacturing and delivery; the possible development of other variants and percentage of vaccination.

The COVID-19 vaccine gives protection against SARS-Cov-2 virus by producing an immune response. Through vaccination risk of developing the illness and its consequences were reduced. These are safe for people of age 18 years and older and those with pre-existing conditions like hypertension, diabetes, asthma, pulmonary, liver and kidney disease, chronic infections which are stable and controlled²

For the first fourteen days after getting vaccination, there is no significant level of protection, after wards it increases gradually. Immunity will generally occur after two weeks with single dose vaccination, but both doses are required to get highest level of immunity.

Myths:

COVID-19 vaccine will never gives a positive result for a COVID-19 RT-PCR test or antigen laboratory test. As the tests check for active disease and not whether an individual is immune or not, because the vaccine prompts an immune response, it may be possible to test positive in an antibody (serology) test that measures COVID-19 immunity in an individual.

Vaccines are usually tested in adults first, to avoid unnecessary exposing in children who are still at developing stage. COVID-19 is more serious and dangerous disease among older populations. Now the vaccines are decided to be effective and safe for adults, further research is required in children³.

The COVID-19 vaccines are expected to produce some protection against new viral variants and effective in preventing serious illness and death. Vaccines produce immune response, if any virus undergoes mutations should not make vaccines completely ineffective. We need to take every possible step to stop the spread of the virus in order to prevent mutations that may reduce the efficacy of existing vaccines. Staying at least 1 meter away from others, covering a cough or sneezes with our elbow, frequently cleaning our hands, wearing a mask and avoid poorly ventilated rooms⁴.

1. Safety of vaccine:

Stringent guide lines have to follow to certify the safety of all COVID-19 vaccines. Before receiving validation from WHO and national regulatory agencies, COVID-19 vaccines must undergo attentive testing in clinical trials to meet internationally agreed benchmarks for safety and effectiveness.WHO and other regulatory authorities are continuously monitor the safety of all the recipients taking vaccines.⁵

Like other vaccines, COVID-19 vaccines also cause mild to moderate short-lasting side effects following vaccination differ according to the specific COVID-19 vaccine, such as a low-grade fever, myalgia, injection site soreness, fatigue, headache, muscle pain, chills, diarrhoea. Most reactions to vaccines are mild and get rid within a few days without taking any medication. More serious or long-lasting side effects to vaccines are possible but extremely rare. Vaccines are continously monitored to detect rare adverse events⁶

The utilisation of COVID-19 vaccines will be strictly monitored by national regulatory authorities and international bodies, including WHO, to detect serious and unexpected adverse effects and helps in better understanding and controlling the specific allergic reactions and other serious effects to COVID-19 vaccines that may not be detected during clinical trials, make sure of safe vaccination to all⁷

The mRNA vaccine technology has been continously assessed for safety and clinical trials have shown that nucleic acid vaccines provide a long-lasting immune response, studied for several decades, including in the development of Zika, rabies and influenza vaccines. As they are inactivated viral vaccines without interfere with human DNA⁸

2. Vaccines Protection:

'Herd immunity' or 'population immunity' is resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination. It does not mean unvaccinated or individuals who have not previously been infected are immune by themselves⁹

The main important reasons to get vaccination are to protect ourselves and the people around us. Everyone cannot be vaccinated – includes children, who are seriously ill or having certain allergic reactions – they depend on others being vaccinated to ensure they are also safe from vaccine-preventable diseases.

World Health Organization is one of the leaders of a global alliance known as COVAX, the vaccine pillar of the ACT-Accelerator collaboration, whose role is to accelerate the development and manufacturing of COVID-19 vaccines and ensures their fair and equitable access for all countries¹⁰.

The aim of COVAX is to provide at least 2 billion vaccine doses by the end of 2021.

The WHO Emergency Use Listing (EUL) is a procedure for assessing unlicensed vaccines, therapeutics and in vitro diagnostics during public health emergencies with the ultimate goal of presenting the availability of those products to needy people.

When products are not licensed yet (still in development), WHO will assess the quality, safety and efficacy data generated during development and conduct a risk-benefit assessment to decide whether they can be used outside clinical trials.

All eligibility criteria are applicable which includes if the disease may cause an outbreak, epidemic or pandemic, If no product having capability of eradicating or prophylacting the disease; products are manufactured in compliance with good manufacturing practices.

There are four categories of vaccines in clinical trials:

A) Whole virusVaccines:

· Whole viruses were used in many conventional vaccines to generate an immune response. Two main approaches are

· Weakened form of the virus can be used in live attenuated vaccines which can still replicate without causing illness.

· Virus genetic material was destroyed and used in inactivated vaccines which cannot replicate, but still trigger an immune response and can be given to immune compromised people, which requires cold storage.

· Well-established technology and pathways for regulatory approval were used in both types of approaches, but live attenuated vaccines might cause disease in immuno compromised people.

· Eg: Sinopharm, Sinovac - both use inactivated viral pathogens, they cannot infect cells and replicate, but can generate an immune response.

· Covaxin vaccine (Bharath Biotech)- Route of administration is Intramuscular

· Other licensed vaccines like Hepatitis A, polio, rabies (all inactivated type) followed this type of technology.

B) Protein SubunitVaccines:

· Harmless fragments of protein or protein shells of virus were used by subunit vaccines which mimic the COVID-19 virus to safely trigger an immune response and to minimize the risk of side effects. Adjuvants were added to boost the immune response. Hepatitis B vaccine is an example of existed subunit vaccine¹¹

Eg: Novavax and Chinese Academy of Sciences- 2 doses, intramuscular

· Other licensed vaccines like Hepatitis B, meningococcal disease, pneumococcal disease and shingles followed this type of technology, which is relatively complex to manufacture and requires booster shots.

C) Viral Vector Vaccines:

· Viral vector vaccines use a safe virus which cannot cause disease but serves as a platform to produce viral proteins which mimic the natural viral infection to generate a strong resistant response.

· They use a harmless virus utilizes our own cellular machinery to produce the antigen from those instructions, in order to trigger an resistant response.¹²

Eg: Oxford-AstraZeneca –is the first viral vector vaccine to be approved for Covid-19.

Sputnik V (Gamaleya Research Institute) – 2 doses- Intramuscular

Covishield (Serum institute of India) - 2 doses- Intramuscular

Johnson and Johnson vaccine - 2 doses- Intramuscular

· Other licensed vaccines like Ervebo (rVSV-ZEBOV) Ebola vaccine – carrier was vesicular stomatitis, where as in COVID-19 vaccine, spike protein was the vector present on the surface of virus.

· This type of vaccine uses an unrelated harmless viral vector to produce SARS-CoV-2 genetic material. After administration, our body cells utilize the genetic material to produce a specific viral protein, which is recognized by our immune system and builds immune memory response, so our body can fight off the virus in future.

These are a cutting-edge approach uses genetically engineered RNA or DNA to generate a protein that itself safely produces an immune response, Where as in COVID-19, that is viral spike protein. Once this genetic material entered into human cells, utilizes our cells’ protein factories to generate the antigen which will trigger a resistant response. RNA vaccines need to store at ultra-cold temperatures-70C or lower, which could be a challenge that many of the countries were not having specialized cold storage equipment, particularly low and middle income group countries ¹³Eg: Pfizer-BioNTech, Moderna- 2 doses- Intramuscular

· Other licensed vaccines like cytomegalovirus (CMV), influenza, rabies, and the Zika virus are the examples of mRNA vaccines.The killer T-cells destroy the infected cells, while the B-cells and helper T-cells support antibody production. In the case of Moderna and Pfizer/BioNTech vaccine genetic material RNA codes for a specific viral protein. When administered, our cells use the genetic material from the vaccines to make the protein, which is recognized by your immune system and triggers a specific immune memory response. So our body can fight off SARS-CoV-2 in future ⁽¹¹⁾. Two RNA Covid-19 vaccines have been approved for use: Pfizer-BioNTech and Moderna vaccinesare having 95% efficacy.¹⁴

Fig 1: Covaxin vaccine

Fig2: Protein vaccines

Fig 3: Viral vector vaccines

Fig 4: Covishield vaccine

Fig 5: Genetic vaccine

Table- 1 Vaccines Information

Vaccine Brand Name	Age	No. of Shots required	Time for Fully Vaccination
Pfizer-BioNTech	16 years and older	2 shots	3 weeks (21 days) after first shot
Moderna	18 years and older	2 shots	4 weeks (28 days) after first shot
Johnson and Johnson’s Janssen	18 years and older	1 shot	2 weeks after first shot
Covishield	18 years and older	3 shots	84 days after first shot.9 months after second shot
Covaxin	18 years and older	3 shots	6 weeks after first shot. 9 months after second shot
Corbevax	18 years and older	2 shots	28 days after first shot
Covovax	18 years and older	2 shots	21 days after first shot

CONCLUSION:

Vaccination is the most effective and safest way to prevent disease and save lives.During the COVID-19 pandemic, vaccination had become critically important. Due to pandemic there was a decline in the routine immunizations for number of children, which results in increase in illness and death from preventable diseases. Therefore vaccine is a safe and clever way to generate an immune response in the body, without causing illness ¹⁵

Scientists around the world are developing many potential vaccines for COVID-19 to safely recognize and block the virus that causes COVID-19. Presently, there is no proof that any vaccines, especially designed for the SARS-Cov-2 virus, will shield against COVID-19.However, scientists are on research that existing vaccines – such as the Bacille Calmette-Guerin (BCG) vaccine, which is used to prevent tuberculosis – is also effective for COVID-19. WHO will evaluate evidence from these studies when available. Omicron may be causing milder symptoms, but it could still be fatal for the elderly and those with comorbidities. Vaccines are controlling transmission and in ensuring cellular immunity even if antibody titers may become less with time. New variants are expected to be more infectious to replace the existing dominant ones. Face masks should become part of our social etiquette because by protecting yourself, you will be safeguarding your own vulnerable family members and friends.

REFERENCES:

1. Deepa Dongarwar et.al. covid 19 vaccination rates by global universal health care coverage status. International Journal of Translational Medical research and public health.2021, 5 (1), 33-36.doi.org/10.21106/ijtmrph.328

2. Saraswathi. K.N, Lissa J. A study to assess the knowledge on selected optional vaccine among mothers of under five children in selected immunization centers at Mysore with view to develop information booklet. Asian Journal of Nursing Education and Research.2014; 4 (4): 513-515. doi.org/10.5958/2349-2996

3. Gurvishal Sinha. The vista of Pandemic in the world and its adaptation by Society: Statistical significant precautions on COVID. Asian Journal of Management. 2020; 11(4):453-456. doi.org/10.5958/2321-5763

4. Amit S et.al.. Early rate reductions of SARS-CoV-2 infection and COVID-19 in BNT162b2 vaccine recipients. Lancet. 2021 Mar 6. 397 (10277):875-877.10.1016/S0140-6736(21)00448-7

5. Baden RL et.al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. N Engl J Med. 2021 Feb 4. 384 (5):403-416.10.1056/NEJMoa2035389

6. Ritika Gupta. The Management of Coronavius Pandemic 2019-2020.Asian journal of Pharmaceutical Research. 2020; 10(4):327-330.10.5958/2231-5691.2020.00056.8

7. Dhanashri U. Gadhave, Puja S. Gaikwad, Nayana V. Pimpodkar, Swati B. Udugade. DNA Vaccines: A hopefull ray in Immunology.Asian Journal of Research in Pharmaceutical Sciences 2015; 5(2): 126-131.10.5958/2231-5659.2015.00020.X

8. SubhashisDebnath, RunaChakravorty, DonitaDevi.A Review on Role of Medicinal plants in Immune system. Asian Journal of Pharmacy and Technology2020; 10(4):273-277.10.5958/2231-5713.2020.00045.8

9. Anupam Srivastava, A K Meena, Kiran Srivastava, Varun Gupta, KaminiKaushal.Socio Economic Impact of COVID- A Review. Asian Journal of Research in Chemistry,2020; 13(6):497-501.10.5958/0974-4150.2020.00088.7

10. Norbert Pardi, Michael J. Hogan, Frederick W. Porter, Drew Weissman. 2018 mRNA vaccines – a new era in vaccinology Nature Reviews Drug Discovery.2018, 17 261–279.doi:10.1038/nrd.2017.243

11. Polack et al. 2020 Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine New England Journal of Medicine 383 2603–2615.10.1056/NEJMoa2034577

12. Ritik S. Jain, Tejas G. Jain, Suraj K. Ishikar. Impact of Covid-19 on Changing Habits and Health Issues of the Public. Asian Journal of Management. 2020; 11(4):524-528.10.5958/2321-5763.2020.00077.3

13. Soumya M, R Deepa. Herd Immunity. International Journal of Nursing Education and Research. 2021; 9(1):125-127.10.5958/2454-2660.2021.00032.6

14. VishwanathBiradar, PreranaDalvi. Impact of COVID19 on Child Health: Parents Perspective. International Journal of Nursing Education and Research.2020; 8(4):463-467.10.5958/2454-2660.2020.00102.7

15. Akshay R. Yadav, Shrinivas K. Mohite. A Novel Approach for Treatment of COVID-19 with Convalescent Plasma. Research Journal of Pharmaceutical Dosage Forms and Technology, 2020; 12(3):227-230. 10.5958/0975-4377.2020.00037.3

Received on 16.10.2021 Modified on 26.12.2021

Research J. Pharm. and Tech 2023; 16(1):465-469.

DOI: 10.52711/0974-360X.2023.00079