What’s The Difference Between Covid-19 Coronavirus Vaccines

Coronavirus COVID-19 single dose small vials and multi dose in scientist hands concept. Research for new novel corona virus immunization drug.

The world can’t return to normal without safe and effective vaccines against the SARS-CoV-2 coronavirus along with a coordinated global vaccination programme.

Researchers have been racing to develop potential drugs that could help end the ongoing Covid-19 pandemic. There are currently around 200 vaccine candidates and about a quarter passed preclinical tests and are now undergoing clinical trials.

What’s the difference between the various candidate vaccines?

A pie chart of candidates can be cut several ways. One is to slice it into six uneven pieces according to the technology (or ‘platform’) that’s used to produce the drug. Those six technologies can be grouped into three broader categories: dead or disabled viruses, artificial vectors, and viral components.

Dead or disabled viruses

Traditional vaccines contain a dead or disabled virus, designed to be incapable of causing severe disease while also provoking an immune response that provides protection against the live virus.

1. Live-attenuated viruses

Attenuated means ‘weakened’. Weakening a live virus typically involves reducing its virulence — capacity to cause disease — or ability to replicate through genetic engineering. The virus still infects cells and causes mild symptoms.

For a live-attenuated virus, an obvious safety concern is that the virus might gain genetic changes that enable it to revert back to the more virulent strain. Another worry is that a mistake during manufacturing could produce a defective vaccine and cause a disease outbreak, which once happened with a polio vaccine. MORE FOR YOUJapan Has Opened Hayabusa2’s Capsule, Confirming It Contains Samples From Asteroid RyuguDonald Trump’s Presidency Will End On The Day Of A Comet, A Meteor Shower And A Total Eclipse Of The SunIn A New Epidemiological Study, Daily Doses Of Glucosamine/Chondroitin Are Linked To Lower All-Cause Mortality

But using a live-attenuated virus has one huge benefit: vaccination resembles natural infection, which usually leads to robust immune responses and a memory of the virus’ antigens that can last for many years.

Live-attenuated vaccines based on SARS-CoV-2 are still undergoing preclinical testing, developed by start-up Codagenix and the Serum Institute of India.

2. Inactivated viruses

Inactivated means ‘dead’ (‘inactivated’ is used because some scientists don’t consider viruses to be alive). The virus will be the one you want to create a vaccine against, such as SARS-CoV-2, which is usually killed with chemicals.

Two Chinese firms have developed vaccines that are being tested for safety and effectiveness in large-scale Phase III clinical trials: ‘CoronaVac’ (previously ‘PiCoVacc’) from Sinovac Biotech and ‘New Crown COVID-19’ from Sinopharm. Both drugs contain inactivated virus, didn’t cause serious adverse side-effects and prompted the immune system to produce antibodies against SARS-CoV-2.

Sinopharm’s experimental vaccine has reportedly been administered to hundreds of thousands of people in China, and both drugs are now being trialled in countries across Asia, South America and the Middle East.

COVID-19 vaccine landscape (left) and platforms for SARS-CoV-2 vaccine development (right)
The global COVID-19 vaccine landscape (left) and Vaccine platforms used for SARS-CoV-2 vaccine … [+] Springer

Artificial vectors

Another conventional approach in vaccine design is to artificially create a vehicle or ‘vector’ that can deliver specific parts of a virus to the adaptive immune system, which then learns to target those parts and provides protection.

That immunity is achieved by exposing your body to a molecule that prompts the system to generate antibodies, an antigen, which becomes the target of an immune response. SARS-CoV-2 vaccines aim to target the spike protein on the surface of coronavirus particles — the proteins that allows the virus to invade a cell.

3. Recombinant viruses

A recombinant virus is a vector that combines the target antigen from one virus with the ‘backbone’ from another — unrelated — virus. For SARS-CoV-2, the most common strategy is to put coronavirus spike proteins on an adenovirus backbone.

Recombinant viruses are a double-edged sword: they behave like live-attenuated viruses, so a recombinant vaccine comes with the potential benefits of provoking a robust response from the immune system but also potential costs from causing an artificial infection that might lead to severe symptoms.

A recombinant vaccine might not provoke an adequate immune response in people who have previously been exposed to adenoviruses that infect humans (some cause the common cold), which includes one candidate developed by CanSino Biologics in China and ‘Sputnik V’ from Russia’s Gamaleya National Research Centre — both of which are in Phase III clinical trials and are licensed for use in the military.

To maximize the chance of provoking immune responses, some vaccines are built upon viruses from other species, so humans will have no pre-existing immunity. The most high-profile candidate is ‘AZD1222’, better known as ‘ChAdOx1 nCoV-19’ or simply ‘the Oxford vaccine’ because it was designed by scientists at Oxford University, which will be manufactured by AstraZeneca. AZD1222 is based on a chimpanzee adenovirus and seems to be 70% effective at preventing Covid-19.

Some recombinant viruses can replicate in cells, others cannot — known as being ‘replication-competent’ or ‘replication-incompetent’. One vaccine candidate that contains a replicating virus, developed by pharmaceutical giant Merck, is based on Vesicular Stomatitis Virus (VSV), which infects guinea pigs and other pets.

4. Virus-like particles

A virus-like particle, or VLP, is a structure assembled from viral proteins. It resembles a virus but doesn’t contain the genetic material that would allow the VLP to replicate. For SARS-CoV-2, the VLP obviously includes the spike protein.

One coronavirus-like particle (Co-VLP) vaccine from Medicago has passed Phase I trials to test it’s safe and has entered Phase II to test that it’s effective.

While there are currently few VLPs being developed for Covid-19, the technology is well-established and has been used to produce commercial vaccines against human papillomavirus (HPV) and hepatitis B.

Viral components

All vaccines are ultimately designed to expose the immune system to parts of a virus, not the whole thing, so why not deliver just those parts? That’s the reasoning behind vaccines that only contain spike proteins or spike genes.

5. Proteins

Protein-based vaccines can consist of the full-length spike protein or the key part, the tip of the spike that binds the ACE2 receptor on the surface of a cell — ACE2 is the lock that a coronavirus picks in order to break into the cell.

Manufacturing vaccines containing the protein alone has a practical advantage: researchers don’t have to deal with live coronaviruses, which should be grown inside cells within a biosafety level-3 lab.

A vaccine against only part of the protein — a ‘subunit’ — will be more vulnerable to being rendered useless if random mutations alter the protein, known as ‘antigenic drift‘, but full-length proteins are harder to manufacture. The immune system can recognize either as an antigen.

One candidate vaccine based on protein subunits is ‘NVX-CoV2373’ from Novavax, where the spike subunits are arranged as a rosette structure. It’s similar to a vaccine that’s already been licensed for use, FluBlok, which contains rosettes of protein subunits from the influenza virus.

6. Nucleic acids

Nucleic-acid vaccines contain genetic material, either deoxyribonucleic acid or ribonucleic acid — DNA or RNA. In a coronavirus vaccine, the DNA or RNA carries genetic instructions for producing a spike protein, which is made within cells.

Those spike genes can be carried on rings of DNA called ‘plasmids’, which are easy to manufacture by growing them in bacteria. DNA provokes a relatively weak immune response, however, and can’t simply be injected inside the body — the vaccine must be administered using a special device to force DNA into cells. Four DNA-based candidates are in Phase I or II trials.

The two most famous nucleic-acid vaccines are the drugs being developed by pharmaceutical giant Pfizer, partnered with BioNTech, and Moderna. Pfizer’s ‘BNT162b2’ and Moderna’s ‘mRNA-1273’ both use ‘messenger RNA’ — mRNA — to carry the spike genes and are delivered into cells via a lipid nanoparticle (LNP). The two mRNA vaccines have completed Phase III trials and preliminary results suggests they’re over 90% effective at preventing Covid-19.

As the above examples show, not only there are many potential vaccines but also various approaches. And while some technologies have already provided promising results, it remains to be seen which will actually be able to defeat the virus.

Full coverage and live updates on the CoronavirusFollow me on Twitter or LinkedIn. Check out my website or some of my other work here

JV Chamary

JV Chamary

I’m a science communicator specialising in public engagement and outreach through entertainment, focusing on popular culture. I have a PhD in evolutionary biology and…

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TODAY

Dr. Ashish Jha, dean of Brown University’s School of Public Health, joins the 3rd hour of TODAY to break down the differences between Moderna’s and Pfizer’s coronavirus vaccine candidates. He also comments on speculation of another national shutdown and whether families should still get together over Thanksgiving. » Subscribe to TODAY: http://on.today.com/SubscribeToTODAY » Watch the latest from TODAY: http://bit.ly/LatestTODAY About: TODAY brings you the latest headlines and expert tips on money, health and parenting. We wake up every morning to give you and your family all you need to start your day. If it matters to you, it matters to us. We are in the people business. Subscribe to our channel for exclusive TODAY archival footage & our original web series. Connect with TODAY Online! Visit TODAY’s Website: http://on.today.com/ReadTODAY Find TODAY on Facebook: http://on.today.com/LikeTODAY Follow TODAY on Twitter: http://on.today.com/FollowTODAY Follow TODAY on Instagram: http://on.today.com/InstaTODAY Follow TODAY on Pinterest: http://on.today.com/PinTODAY#COVID19Vaccines#AshishJha#TodayShow

Vaccine To Have Marginal Impact On Winter Pressures As Rollout Work Continues

The UK’s chief medical officers have warned the coronavirus vaccine will only have a “marginal impact” on hospital numbers over the winter as each of the four nations prepares to start administering the first doses next week.

Festive gatherings are likely to put additional pressure on healthcare services, with a tough few months still ahead, experts said.

It comes as preparations are continuing to roll out the Pfizer/BioNTech vaccine from as early as Tuesday in what has been described as “one of the greatest challenges the NHS has ever faced”.

GP surgeries in England have also been told to be ready to start staffing Covid-19 vaccination centres by December 14.

In a letter to colleagues, the four chief medical officers said this winter would be “especially hard” for the health service due to coronavirus.

“Although the very welcome news about vaccines means that we can look forward to 2021 with greater optimism, vaccine deployment will have only a marginal impact in reducing numbers coming into the health service with Covid over the next three months,” they said.

“The actions and self-discipline of the whole population during lockdowns and other restrictions have helped reduce the peak and in most parts of the four nations hospital numbers are likely to fall over the next few weeks, but not everywhere.

“The social mixing which occurs around Christmas may well put additional pressure on hospitals and general practice in the New Year and we need to be ready for that.”

The letter, signed by chief medical officer of England, Professor Chris Whitty; of Scotland, Dr Gregor Smith; of Wales, Dr Frank Atherton; and of Northern Ireland, Dr Michael McBride, said they did not expect the virus to “disappear” even once full vaccination had occurred.

The first jabs will be administered in each of the UK nations on Tuesday. In Northern Ireland it will be administered at a mass vaccination centre at the Royal Victoria Hospital in Belfast, while in Wales frontline NHS and social care staff will receive the country’s first coronavirus vaccine.

The first vaccinations will also take place in Scotland next week, while jabs will be administered at hospital hubs in England.

Meanwhile, in a letter sent out across England’s primary care networks, NHS England and NHS Improvement said GP-led vaccination centres would start administering doses from December 14.

The letter said centres would be set up with the necessary IT equipment and a fridge, while staff would be given training to ensure they are ready to administer 975 doses of the vaccine to priority patients within three-and-a-half days of delivery.

The first to receive the vaccine in these centres will be those aged 80 and over, as long as other risk factors, “clinical or otherwise”, have been taken into account.

There remain issues around how to ensure elderly residents in care homes, who have been recommended as the top priority, get access to a jab due to difficulties in storing and transporting the Pfizer/BioNTech version as its cold temperature – minus 70C – limits how often it can be moved.

HEALTH Coronavirus Oxford
(PA Graphics) Credit: PA Graphics

NHS England has not yet committed to a date to roll the vaccine out in English care homes, but Dr June Raine, chief executive of the Medicines and Healthcare products Regulatory Agency, told the BBC on Friday that she estimated the vaccine would begin to be delivered to care homes “within the next two weeks”.

In total, some 40 million doses of Pfizer’s inoculation are on order – enough to administer it to 20 million people, with two jabs required 21 days apart.


By: https://www.itv.com

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Healthy Lifestyle

Vaccines will only have ‘marginal impact’ on NHS winter pressures, chief medical officers warn COVID-19 will keep hospitals under continued strain in the coming months as new vaccines will only have a “marginal impact” on patient numbers over winter, the UK’s chief medical officers have warned. In a letter written to healthcare colleagues, the group – which includes England’s Professor Chris … Home remedies refer to “practical cure or treatment that cures, heals or relieves” using certain common substances such as spices, vegetables, fruit, herbs and modern materials. Click Here: https://remediesnew.com

CanSino’s COVID-19 Vaccine Candidate Approved For Military Use In China

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FILE PHOTO: Small bottles labeled with a “Vaccine COVID-19” sticker and a medical syringe are seen in this illustration taken taken April 10, 2020. REUTERS/Dado Ruvic/File Photo

BEIJING (Reuters) – China’s military has received the greenlight to use a COVID-19 vaccine candidate developed by its research unit and CanSino Biologics (6185.HK) after clinical trials proved it was safe and showed some efficacy, the company said on Monday.

The Ad5-nCoV is one of China’s eight vaccine candidates approved for human trials at home and abroad for the respiratory disease caused by the new coronavirus. The shot also won approval for human testing in Canada.

China’s Central Military Commission approved the use of the vaccine by the military on June 25 for a period of one year, CanSino said in a filing. The vaccine candidate was developed jointly by CanSino and a research institute at the Academy of Military Science (AMS).

“The Ad5-nCoV is currently limited to military use only and its use cannot be expanded to a broader vaccination range without the approval of the Logistics Support Department,” CanSino said, referring to the Central Military Commission department which approved the military use of the vaccine.

CanSino declined to disclose whether the innoculation of the vaccine candidate is mandatory or optional, citing commercial secrets, in an email to Reuters.

The military approval follows China’s decision earlier this month to offer two other vaccine candidates to employees at state-owned firms travelling overseas.

The Phase 1 and 2 clinical trials of the CanSino’s vaccine candidate showed it has the potential to prevent diseases caused by the coronavirus, which has killed half a million people globally, but its commercial success cannot be guaranteed, the company said.

Separately, AMS received an approval earlier this month to test its second experimental coronavirus vaccine in humans.

No vaccine has yet been approved for commercial use against the illness caused by the new coronavirus, but over a dozen vaccines from more than 100 candidates globally are being tested in humans.

Reporting by Roxanne Liu and Ryan Woo; Editing by Miyoung Kim and Ana Nicolaci da Costa

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CanSino Biologics, a Chinese company developing a COVID-19 vaccine with the help of some Canadian scientists, saw some early success in the first phase of clinical trials. Welcome to The National, the flagship nightly newscast of CBC News. »»» Subscribe to The National to watch more videos here: https://www.youtube.com/user/CBCTheNa… Voice your opinion and connect with us online: