They stimulate your immune system to produce antibodies, as if you were exposed to the germ 

IMMUNITY DEVELOPEDW 

After getting vaccinated, one develops immunity to that disease without having to get it first 

STAGES OF DEVELOPMENT

Pre-clinical phase

• Normally occurs before human testing can begin
• Collects data to support feasibility and safety
• Involves repeated non-human testing 
• Evaluates toxic and pharmacological effects

Clinical phase I

• Small study on healthy persons
• Evaluates safety and immune response at different doses
• Typically takes 1-2 years, but for COVID-19 trials, expected to take only 3 months

Clinical phase II

• Studies 100s of people
• Further evaluates safety, assesses efficacy, and informs optimal dose and vaccine schedule
• Typically takes 2-3 years, but expected to take 8 months for COVID-19 trials

Clinical phase III

• Studies 1000s of people
• Further evaluates safety and efficacy
• Typically takes 2-4 years, but may be combined with Phase II

REGULATORY REVIEW

• Government agency reviews trial data and licensing application information before approval
• Can happen while manufacturing has started
• Typically takes 1-2 years, but expedited to take only a few months 

Clinical phase IV

• Post-approval studies that monitor effectiveness in real-world conditions
• Testing begins after the vaccine has been released to the public

MANUFACTURING

Developers will try to ensure that enough of a vaccine is ready by the time it is approved. But if the approval doesn't come through, the manufacturer will lose resources. So the risk is directly proportional to the amount of vaccine produced. Let's look at different scenarios to be presented before us 

NON-IDEAL: Developer manufactures mass quantities but does not get approval, leaving the public without a vaccine and resources put into manufacturing lost

GOOD: Developer gets fast approval but has not manufactured enough of a vaccine to distribute in mass quantities. The public must wait longer for more vaccines to become available 

BEST: Developer gets fast approval and has been concurrently manufacturing the vaccine during clinical trials. The vaccine is now ready to distribute in mass quantities

Here is how Russia’s Sechenov First Moscow State Medical University did its clinical trial:

•  First group of 18 healthy volunteers got vaccinated on June 18
• The second group of 20 volunteers received the vaccine on June 23
• The volunteers were within the age group of 18 to 65
• They received a lyophilised vaccine or a powder from which a solution is prepared for intramuscular injection
• Some participants reported headaches and elevated body temperature, but resolved completely within 24 hours
• Participants have been kept in single or double wards on University campus
• They have to spend 28 days in isolation. After discharge, they will be monitored for 6 more months
• Psychological support is provided during isolation

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