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With input from Dr Monica Vasudev
1108 Round Table Expert Zoom Meeting on “Vaccine Update”
10th October, 2020, 11am-12pm
Participants: Dr Jayakrishnan Alapet, Prof Mahesh Verma, Dr Ashok Gupta, Dr Atul Kochhar, Dr Jayalal, Dr Anita Chakravarti, Dr KK Kalra, Dr Anil Kumar, Ms Meenakshi Datta Ghosh, Mrs Upasana Arora, Mr DK Gupta, Ms Ira Gupta, Dr S Sharma
Faculty: Dr KK Aggarwal, President CMAAO
Key points from the discussion
- There is a critical need for a COVID-19 vaccine as there is a need to end this epidemic; also, vaccine could be important to control future epidemics.
- A vaccine is technically feasible, but there are two concerns: possibility of antibody-dependent enhancement and timelines are faster than before, but still not fast enough.
- The process of vaccine development started as early as 10thJanuary, when the virus sequence was shared.
- COVID-19 is an acute (less than 3 months) manageable immunogenic (trigger) thrombogenic (effect) inflammatory notifiable (infectious) viral disease.
- Any vaccine should be able to prevent the entry of the virus and it should also be able to reduce the duration of the disease. The vaccine should be able to take away the immunogenic and thrombogenic character of the virus. It should be able to prevent the disease.
- Either the virus as a whole, or its components (membrane, envelope, spike and nucleoprotein), are used in the vaccine.
- The virus enters the cell through receptor binding domain and membrane fusion.
- A large number of trials (193) of vaccine are going on worldwide. These trials are at various stages; 28 vaccines are in phase 1 trial stage, 14 are in phase 2, 11 are in phase 3 trials and 5 have been given limited approval. No vaccine has been approved.
- Types of vaccine: Live virus, inactivated virus, live attenuated, gene part of the virus, recombinant, spike protein of the virus, monoclonal antibodies, adjuvant.
- A vaccine healthy challenge can be done after giving the vaccine to see if it is effective. Natural exposure in family is happening everyday now.
- Inactivated or killed vaccines are easy to make but do not provide long-lasting immunity; a booster maybe required. Examples are hepatitis A vaccine, injectable polio and flu vaccine. The virus is inactivated with formalin or alcohol.
- Three (CoronaVac – Sinovac Biotech, Sinopharma) out of 5 limited approvals are inactivated or attenuated vaccines.
- Covaxin, the Indian vaccine, is based on inactivated virus.
- Live attenuated vaccines: Examples are MMR, Rotavirus, small pox, chickenpox, yellow fever; produce long-lasting immune response. 1-2 doses may be required. India is working only on BCG recombinant vaccine, not coronavirus. Live attenuated vaccines cannot be produced in short period of time.
- Vectors: Take another virus and add corona protein or part of corona protein into it. Adenovirus is the most commonly used. Vectors are of three types: Human virus 5 and 26, chimpanzee virus and Gorilla virus. Oxford vaccine ChAdOx1 vaccine is a chimpanzee adenovirus vaccine vector. Vector vaccines are easy to make but there are chances of complications (two cases of transverse myelitis have been reported).
- Two ways to get a vaccine early: vector vaccine or live attenuated vaccine. Most ongoing work is on these two types of vaccines.
- Some are working on nasal spray; some are working on weakened measles virus or a pill form.
- Vaccines using coronavirus gene fragments are in preclinical stage.
- Viral vector can be replicating (Ebola virus vaccine) or non-replicating (no currently licensed vaccines are non-replicating). The Russian Sputnik V vaccine is non-replicating viral vector vaccine.
- Vaccines can be subunit, recombinant, polysaccharide and conjugate. These give a very strong immune response and can be used in people with weakened immune systems and long-term health problems. Examples - HiB, HPV, hepatitis B, pneumococcal/meningococcal, shingles.
- Boosters are needed to have ongoing protection.
- Spike protein is the most preferred vaccine target.
- Subunits are coronavirus proteins (RBD, peptides, proteins with adjuvant), but no genetic material.
- Genetic vaccines: Moderna mRNA vaccine is in phase 3 trial. Zydus Cadila is working on a DNA-based vaccine. It is undergoing phase 2 trial.
- Universal vaccine: vaccine made with all existing strains of the virus.
- Some people are working on oral vaccine, adjuvant vaccine.
- In Russia and China, healthcare workers and the military have been given the vaccine as phase 3 trial.
Dr KK Aggarwal
President CMAAO, HCFI and Past National President IMA