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Vaccine Update to protect against COVID19

It seems unimaginable that a vaccine against covid19 vaccine would not eventually be developed. It appears to be matter of when rather than if. Over a hundred labs are working on this project around the world. Labs are trying a mix of different types, mostly mRNA, DNA, VLP( virus like particle ), protein subunit , recombitant viral vector ( mostly adenovirus...some bacterial )etc. The last time we witnessed such a vaccine race was to combat Ebola fever. Eventually the first and only licenced vaccine was Erbevo developed by Public Health Canada, a recombitant viral vector vaccine using VSV ( vescicular stomatitis virus ) as vector. CanSino (Canadian/Chinese collaboration) and Oxford University / Astra Zeneca are both developing adenovirus vector vaccines both entering phase two trials, the most advanced in trials at the moment. In Canada, University of British Columbia is developing a DNA vaccine with bacterial vector vaccine which will be consumed as a probiotic tablet while Medicago is developing a vaccine from plants. This Quebec based company's technique is to first inject part of the Sars-cov2 genetic RNA sequence into soil bacteria. Once this bacterium is taken up by tobacco plants, scientists can then harvest VLP’s ( virus like proteins) from the leaves. Studies on mice induced an immune response within ten days. University of Mannitoba (Canada, where Ebola vaccine was first developed) and two Chinese firms are developing dendritic cell vaccine which was initially developed as chemotherapy for cancer. Two US firms are adapting their intranasal and oral flu vaccine platforms for covid19 . Two collaborations between India and USA are developing live attenuated vaccine which contains live covid19 virus which has been attenuated ( weakened). I find this particularly interesting because this is an existing time tested technique rather than the cutting edge technologies being used elsewhere. Once China made the RNA sequence of SARS-COV2 available early January, labs around the world could get started on a synthetic RNA vaccine and are got a head start. Many of these RNA platforms were being developed for SARS-COV1 but could not reach fruition before the epidemic itself died down. However we must bear in mind that no RNA vaccine has ever been licensed for humans. . A DNA vaccine was eventually developed for MERS and used on USA troops deployed in the middle east. Synthetic technologies can be mass produced much quicker since one is not restricted by having to grow the virus in egg yolk culture for instance. Also, vaccines using live virus could harbour risks during production such as leakage ( as may have happened at Wuhan).
The usual vaccines that we are accustomed to are rather different to most of the vaccines being developed against COVID19. As an example BCG , MMR and Yellow Fever vaccines are live attenuated ( weakened ) vaccines. IPV, cholera and rabies vaccines are inactivated. Antibacterial vaccines are usually polysacharride ( inducing response against capsular sugars of the bacterium) or conjugate in which this sugar is paired with a protein to enhance antigenicity as in case of Prevnar13 and HIB. While HAV vaccine is usually inactivated, HBV vaccine is probably the commonly used vaccine closest to advanced vaccines being developed against SARS-COV2. Heptitis B vaccine is a recombitant DNA subunit vaccine produced by introducing DNA sequence into yeast cells. The antigens expressed by yeast cells can be isolated and injected. Another example of a yeast cultured vaccine is HPV where virus like particles containing protein capsid of HPV are produced and inoculated. At this time I am betting on a vector based vaccine similar to the Ebola vaccine rather than the much touted and publicized mRNA vaccines. In any case, lets keep our fingers crossed that scientists will find a way....will keep you updated
 

INFORMATION & DISCLAIMER: 

I obtained my primary medical education from India and post graduate MD in Family Medicine from the United Kingdom. After working in the NHS for 15 years, I moved to  Canada five years ago.  As a Family Physician, my specialty is engaging patients, interpreting medical information for them, guiding them through their health journey, promoting wise health choices and encouraging early detection and management of disease. The information on this blog is accurate as per time of publishing and patients should check the main blog for updates. Scientific information and evidence changes dynamically and my opinions would change accordingly. The recommendations on this blog are not prescriptions and any patients considering these should consult with a physician to check if these are applicable to their unique case. Patient confidentiality must be upheld at all times and any patients wishing to discuss specific medical scenarios on social media are requested to do so anonymously in 'third party' sense. 

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