Adenovirus COVID-19 vaccine (Ad5-nCoV)
Source | The Hindu
GS Paper III: Science and Technology – developments and their applications and effects in everyday life Achievements of Indians in science & technology; indigenization of technology and developing new technology.
- Adenovirus COVID-19 vaccine has found to be safe and induces immune responses.
- The trial was carried out on 108 participants aged 18-60 years in Wuhan, China, and had 36 participants each in the low, middle and high-dose groups.
Read More: ChAdOx1 nCoV-19 | Human Trials in UK
Context: A phase-1 trial using a single dose of a vaccine (Ad5-nCoV) that uses a recombinant adenovirus type-5 vector (the adenovirus is a weakened common cold virus) that carries the genetic material that codes for spike glycoprotein of novel coronavirus was found to be safe, well-tolerated and able to generate immune responses against the virus.
Key Details about the Phase 1 trial of Adenovirus COVID-19 Vaccine (Ad5-nCoV)
The trial on the adenovirus covid-19 vaccine (Ad5-nCoV) was carried out on 108 participants aged 18-60 years in Wuhan, China, and had 36 participants each in the low, middle and high-dose groups.
- As it was a first-in-human study of the adenovirus type-5 vectored COVID-19 vaccine, it was not designed to measure the vaccine efficacy.
- The vaccine was found to elicit neutralising antibodies, which peaked at day 28 post-vaccination, while rapid specific T-cell responses peaked at day 14 after vaccination.
- The antibody response to the vaccine in the high-dose group was slightly greater than that in the middle-dose and low-dose groups.
- The vaccine also stimulated a rapid T cell response in the majority of volunteers, which was greater in those given the higher- and middle-doses of the vaccine, with levels peaking at 14 days after vaccination.
What you need to know about Phases of Clinical Trials?
Clinical trials involving new drugs are commonly classified into four phases. Individual trials may encompass more than one phase. The drug development process will normally proceed through all four phases over many years.
- If the drug successfully passes through Phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population.
- Phase IV are ‘post-approval’ studies.
- The entire process of developing a drug from preclinical research to marketing can take approximately 12 to 18 years and often costs well over $1 billion.
PHASE I CLINICAL TRIALS
- These trials are the first stage of testing in human subjects.
- They are designed to test the safety, side effects, best dose, and formulation method for the drug.
- Normally, a small group of 20–100 healthy volunteers will be recruited.
- These trials are often conducted in a clinical trial clinic, where the subject can be observed by full-time staff.
PHASE II CLINICAL TRIALS
- Phase II trials are performed on larger groups (100–300)
- These are designed to assess how well the drug works, as well as to continue Phase I safety assessments in a larger group of volunteers and patients.
- When the development process for a new drug fails, this usually occurs during Phase II trials when the drug is discovered not to work as planned, or to have toxic effects.
- Phase II clinical programs historically have experienced the lowest success rate of the four development phases.
Read More: SOLIDARITY TRIAL: WHO AMID COVID-19
PHASE III CLINICAL TRIALS
- This phase is designed to assess the effectiveness of the new intervention and, thereby, its value in clinical practice.
- Phase III studies are randomized controlled multicenter trials on large patient groups (300–3,000 or more depending upon the disease/medical condition studied).
- These are aimed at being the definitive assessment of how effective the drug is, in comparison with current ‘gold standard’ treatment.
- Because of their size and comparatively long duration, Phase III trials are the most expensive, time-consuming and difficult trials to design and run, especially in therapies for chronic medical conditions.
- This is sometimes called the “pre-marketing phase” because it actually measures consumer response to the drug.
- While not required in all cases, it is typically expected that there be at least two successful Phase III trials, demonstrating a drug’s safety and efficacy, in order to obtain approval from the appropriate regulatory agencies.
- As of 2010, about 50% of drug candidates either fail during the Phase III trial or are rejected by the national regulatory agency.
PHASE IV CLINICAL TRIALS
- Phase IV trial is also known as postmarketing surveillance trial, or informally as a confirmatory trial.
- This involve the safety surveillance (pharmacovigilance) and ongoing technical support of a drug after it receives permission to be sold.
- Phase IV studies may be required by regulatory authorities or may be undertaken by the sponsoring company for competitive (finding a new market for the drug) or other reasons.
- The safety surveillance is designed to detect any rare or long-term adverse effects over a much larger patient population and longer time period than was possible during the Phase I-III clinical trials.
- Harmful effects discovered by Phase IV trials may result in a drug being no longer sold, or restricted to certain uses.
- The minimum time period mandatory for Phase IV clinical trials is 2 years.
ALSO READ: CORO-FLU: VACCINE TO COMBAT COVID-19
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