Why is COVID referred to as a Vector-based disease?
Vector-based diseases are caused by pathogens and are contagious. It is not yet established whether COVID is caused by virus or bacteria. Pathogens cover four broad categories viz. viruses, bacteria, fungi and parasites. The term vector-based is used for COVID because the actual cause of the disease is yet to be established. The only thing known is that it is caused by one of the pathogens and it is contagious. That is what vector-based means.
What is the difference between drug approval and emergency use approval (EUA)?
Any drug or vaccine has to be approved by a government authorized agency like the FDA in the US or the DCGI in India. The drug approval process is very elaborate and has to go through multiple levels of testing and observation. In a pandemic situation, countries are racing against time. Hence a special emergency usage approval (EUA) is given in such cases.
Unlike the normal drug approval, the EUA is much quicker and is normally used in pandemics. In such cases, it is not a blanket approval but the production and distribution can be done till the pandemic ends and in a specified geographical area.
What is the difference between Adverse Event and Background Rate in drug testing?
Both concepts are related to one another, although different. An adverse event is a health problem that crops up in volunteers in a clinical trial of a vaccine or drug. This adverse event may or may not be a direct outcome of the vaccine, but could be triggered by other reasons.
On the other hand, the Background Rate measures how often a health problem, i.e. an adverse event, arises in the general population. Background Rate measures the probability of adverse events and determines whether the vaccine or a drug is safe.
Which vaccines will be available in India for COVID-19? Why Pfizer vaccine is not being used in India?
Currently, the Drug Controller General of India (DCGI) has given emergency usage authorization (EUA) to Covishield and Covaxin. The Covishield vaccine was jointly developed by AstraZeneca PLC and Oxford Research, UK. In India, this vaccine will be manufactured and distributed by Serum Institute of India. The Covaxin is the only indigenously developed vaccine in India. It was developed by Hyderabad based Bharat Biotech in collaboration with National Institute of Virology, Pune and Indian Council of Medical Research (ICMR).
The reason India did not go ahead with the Pfizer-BionTech vaccine is that it requires refrigeration at a level that is not commercially available in India. While Covishield and Covaxin have to be kept in normal refrigeration temperatures of (-8 to -12 degrees), the Pfizer-BionTech vaccine needs storage at temperatures of (-70 degrees).
Is the efficacy and effectiveness of the vaccine one and the same?
When it comes to vaccine testing, efficacy and effectiveness are two different things. For example, while testing the Coronavirus vaccine, researchers compare how many people in the vaccinated and placebo groups contracted COVID-19. That is efficacy. On the other hand, Effectiveness is the benefit that a vaccine or a drug provides in the real world. The vaccine's effectiveness may eventually be lower or higher than its efficacy. Covishield has an efficacy rate of 70% while the efficacy of Covaxin is yet to be established.
How are Phase 1, Phase 2 and Phase 3 trials of the vaccine different?
There are 3 stages to the clinical trial of a vaccine. Phase 1 trials involve a few dozen people and only intended to observe whether the vaccine or drug is safe. Phase 2 trials involve hundreds of people and allow the researchers to try out permutations and combinations to test the impact on the immune system. The last Phase 3 trials, involves thousands of volunteers and tests how many are actually protected from the disease.
How is the vaccine different from a placebo in vaccine testing?
The vaccine usually contains a protein produced by the immune system that can attach to a pathogen like the Coronavirus and stop it from infecting cells. Covishield is a viral vector vaccine that uses a harmless virus to stimulating ingredients into the human body. On the other hand, a Placebo is a substance with no therapeutic effect; like salt water.
For vaccine testing, researchers inject the vaccine into half the volunteers, while the other half gets a placebo. The vaccine is then tested by checking COVID infections compared to the placebo group. This is an essential part of any clinical trial.
These will surely help you in some jargon busting as the unprecedented vaccine inoculation drive takes off in India.