How India’s 4 vaccine frontrunners will help you fight off coronavirus

Should you go for Bharat Biotech’s Covaxin or Serum Institute’s Covishield? Or wait for Russia’s Sputnik V? Or maybe just hang on till Novavax is cleared? Perhaps you shouldn’t worry too much: all vaccines try to do the same thing — expose the immune system to the germs of the disease they are designed to combat. Some use a weakened germ while others rely on basic genetic instructions to prompt an immune response.OXFORD-ASTRAZENECA & GAMALEYA INSTITUTE | NON-REPLICATING VIRAL VECTOR VACCINE Both vaccines seek to smuggle into the human body key pieces of the coronavirus embedded in a separate, harmless virus that cannot make the recipient ill. Both are non-replicating, which means the viral particle in the vaccine cannot replicate within the body. It can only nudge the body to create the specific part of the coronavirus that was enclosed within the harmless carrier, which in turn prompts the immune system to act against it. There are also replicating viral vector vaccines, such as one for Ebola, where the viral material can itself replicate within the body while priming the immune system. !function(){"use strict";window.addEventListener("message",(function(a){if(void 0!==a.data["datawrapper-height"])for(var e in a.data["datawrapper-height"]){var t=document.getElementById("datawrapper-chart-"+e)||document.querySelector("iframe[src*='"+e+"']");t&&(t.style.height=a.data["datawrapper-height"][e]+"px")}}))}(); !function(){"use strict";window.addEventListener("message",(function(a){if(void 0!==a.data["datawrapper-height"])for(var e in a.data["datawrapper-height"]){var t=document.getElementById("datawrapper-chart-"+e)||document.querySelector("iframe[src*='"+e+"']");t&&(t.style.height=a.data["datawrapper-height"][e]+"px")}}))}(); The Covishield vaccine uses an adenovirus that causes common cold in chimpanzees to insert instructions for the human body to produce the Sars-CoV-2 spike protein.BHARAT BIOTECH | INACTIVATED VIRUS VACCINEBharat Biotech’s Covaxin, the first indigenous vaccine approved by the government, uses an inactivated form of the coronavirus. An inactivated virus vaccine, unlike a live virus one, is safer to administer to those with weakened immune systems. Many existing vaccines are of this type, like the ones for measles and polio, but they require extensive safety testing. Also, these vaccines tend to require multiple doses and can take a long time to manufacture in large quantities. !function(){"use strict";window.addEventListener("message",(function(a){if(void 0!==a.data["datawrapper-height"])for(var e in a.data["datawrapper-height"]){var t=document.getElementById("datawrapper-chart-"+e)||document.querySelector("iframe[src*='"+e+"']");t&&(t.style.height=a.data["datawrapper-height"][e]+"px")}}))}(); Although they are seen as being safer than live vaccines, immunity from inactivated vaccines is weaker and so adjuvants – molecules that stimulate the immune system – are often included with inactivated vaccines to give a stronger immune response.Covaxin uses an adjuvant made by USbased ViroVax for enhanced efficacy. Covaxin was shown to be effective in Phase 2 trials but neither the company nor the govt has released efficacy data for Phase 3 trials, drawing criticism from the medical community with some calling it a hasty approval. NOVAVAX | PROTEIN SUBUNIT VACCINEThe vaccine candidate being developed by the US-based Novavax is based on a protein subunit platform, which means it relies on a fragment of the virus to train the immune system to guard against disease instead of the whole virus. The Hepatitis B vaccine is an example of a subunit vaccine. !function(){"use strict";window.addEventListener("message",(function(a){if(void 0!==a.data["datawrapper-height"])for(var e in a.data["datawrapper-height"]){var t=document.getElementById("datawrapper-chart-"+e)||document.querySelector("iframe[src*='"+e+"']");t&&(t.style.height=a.data["datawrapper-height"][e]+"px")}}))}(); For the Novavax shot, spike protein of the coronavirus is extracted from insect cells and injected into the body via nanoparticles that resemble the molecular structure of the coronavirus, but cannot cause Covid-19. These vaccines are considered safe because they use only a fragment of the virus. However, doing so means that the immune response they generate may also be weaker. This is why they often require adjuvants, which are substances that stimulate the immune system, to help boost the immune response. The Novavax vaccine uses its Matrix-M adjuvant.boxcontent medium80132280 medium801322851. Once the vaccine is administered, the virus particles contained within it enter the body. Now, since they are foreign elements that can damage the body, their presence is picked up by what are called ‘antigen-presenting cells’ (APCs). So, you can say the APCs trigger a sort of early warning system when the body is exposed to a virus. APCs ingest the virus and then highlight some portions of it, called antigens, that would enable other cells of the immune system to recognise them 2. Key among the cells that do the actual work of fighting the virus are ‘T helper cells’, which recognise the antigen and then alert other immune cells about fighting the virus 3. One of the cells recruited by the T helper cells is the B cell, which produces specific antibodies against the coronavirus 4. The antibodies not only prevent the virus from invading cells but also tag them so they can be destroyed by other immune cells. T and B cells can now recognise the virus and deploy antibodies in the event of an actual infection*Pre-order data according to media reportsSource: NYT, Gavi, NatureUntitled Carousel 80109956