Blog Date 15 March, 2023

All you need to know about Covid-19

1. Which COVID-19 vaccines are licensed in India?

Two vaccines that have been granted emergency use authorization by the Central Drugs Standard Control Organization (CDSCO)in India are Covishield® (AstraZeneca's vaccine manufactured by Serum Institute of India) and Covaxin® (manufactured by Bharat Biotech Limited)

2. What is Emergency Use Authorization (EUA)/ Permission for restricted use?

Emergency Use Authorization (EUA) is a regulatory mechanism to allow the use of vaccines and medicines to prevent and or reduce the impact of life-threatening diseases or conditions as caused by Covid19. However, before grant of the EUA, there is rigorous assessments of laboratory and clinical trial data, including data on quality, safety, production of protective antibodies and efficacy. Safety is particularly critical aspect of this scrutiny and a risk-versus- benefit evaluation is done in the context of a public health emergency. Full licensure is obtained when the manufacturer submits the complete data.EUA by Indian regulators is aligned with global guidelines.

3. Is the EUA a new process introduced for COVID-19 Vaccine?

Concept of EUA always existed to save the lives of people all over the world with vaccine and medicines for life threatening diseases while companies continue to obtain additional safety and effectiveness information to enable full licensure. Previously, EUAs have been granted to vaccines for outbreaks due to anthrax, Ebola, enterovirus, H7N9 influenza, and Middle East respiratory syndrome. As of January 2021, nine COVID-19 vaccines were in emergency use in numerous countries around the globe.

4. Have the vaccines undergone the needed clinical trials before EUA?

Both the Indian COVID 19 vaccines have completed their Phase I & II trials. Covishield® has completed its Phase III trials in UK and the bridging trial in India.

Bharat Biotech Announces Phase III Results of COVAXIN®: India’s First COVID-19 Vaccine Demonstrates Interim Clinical Efficacy of 78%

5. What is Phase I, II and III of clinical trial for a vaccine?

Phases of vaccine




Vaccine development in laboratory animals

Phase 1 Clinical trial

(small number of participants)

Assess vaccine safety, immune response and determine right dosage (short duration)

Phase 2 Clinical trial

(few hundred participants)

Assess safety and the ability of the vaccine to generate an immune response (short duration)

Phase 3 Clinical trial (thousands of participants)

Determine vaccine effectiveness against the disease and safety in a larger group of people (duration 1-2 years)

6.Why vaccination is not provided to children who are usual target?

COVID-19 affects all age groups; however, morbidity & mortality is several times higher in adults particularly in those above the age of 50 years. Children have either asymptomatic or mild infection.

The general practice is to first evaluate any new vaccine in older population and then age reduction is done to assess the safety and effectiveness in paediatric population. The currently available vaccines have not been evaluated in children so far. There are some clinical trials now underway to test the effectiveness and safety of the COVID 19 vaccines in children.

7.What technology has been used in development of the currently available two vaccines in India?

Covishield® vaccine, manufactured by the Serum Institute of India, is a Viral Vector based Technology which is also used to manufacture Ebola vaccine.

Covaxin® vaccine, manufactured by the Bharat Biotech, is a whole-Virion Inactivated Corona Virus Vaccine which is also used to manufacture vaccines like Influenza, Rabies and Hepatitis- A.

8.What is the dose schedule of both the vaccines?

As per the permission granted by the Drug Controller General (India), duration for second dose of COVISHIELD vaccine will be 84 days to 112 days & duration for second dose of COVAXIN vaccine will be28 days to 42 days

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