From adenoviruses to RNA: the pros and cons of different COVID vaccine technologies



Shutterstock

Suresh Mahalingam, Griffith University and Adam Taylor, Griffith University

The World Health Organisation lists about 180 COVID-19 vaccines being developed around the world.

Each vaccine aims to use a slightly different approach to prepare your immune system to recognise and fight SARS-CoV-2, the virus that causes COVID-19.

However, we can group these technologies into five main types. Some technology is tried and trusted. Some technology has never before been used in a commercial vaccine for humans.

As we outline in our recent paper, each technology has its pros and cons.

Each of these five technologies is designed to prepare your immune system to recognise and respond to a future infection. Author provided.




Read more:
Vaccine progress report: the projects bidding to win the race for a COVID-19 vaccine


1. DNA/RNA-based

DNA and RNA vaccines use fragments of genetic material made in the lab. These fragments code for a part of the virus (such as its spike protein). After the vaccine is injected, your body uses instructions in the DNA/RNA to make copies of this virus part (or antigen). Your body recognises these and mounts an immune response, ready to protect you the next time you encounter the virus.

Pros

  • these vaccines can be quickly designed based on genetic sequencing alone

  • they can be easily manufactured, meaning they can potentially be produced cheaply

  • the DNA/RNA fragments do not cause COVID-19.

Cons

  • there are no approved DNA/RNA vaccines for medical use in humans, hence their alternative name: next-generation vaccines. So they are likely to face considerable regulatory hurdles before being approved for use

  • as they only allow a fragment of the virus to be made, they may prompt a poor protective immune response, meaning multiple boosters may be needed

  • there’s a theoretical probability vaccine DNA can integrate into your genome.

The speed at which these vaccines can be designed, needing only the genetic sequence of the virus, is why these vaccines were among the first to enter clinical trials.

An RNA vaccine, mRNA-1273, being developed by Moderna and the US National Institute of Allergy and Infectious Diseases, advanced to clinical testing just two months after the virus was sequenced.

2. Virus vectors

These vaccines use a virus, often weakened and incapable of causing disease itself, to deliver a virus antigen into the body. The virus’ ability to infect cells, express large amount of antigen and in turn trigger a strong immune response make these vaccines promising.

Examples of viruses used as vectors include vaccinia virus (used in the first ever vaccine, against smallpox) and adenovirus (a common cold virus).

Pros

  • highly specific delivery of antigens to target cells and high expression of antigen after vaccination

  • often a single dose is enough to stimulate long-term protection.

Cons

  • people may have existing levels of immune protection to the virus vector, reducing the effectiveness of the vaccine. In other words, the body raises an immune response to the vector rather than to the antigen

  • low-scale production of some virus-vectored vaccines means they are less cost-effective.

One high-profile example is the University of Oxford/AstraZeneca vaccine AZD1222 (formerly known as ChAdOx1), one of the two vaccines the Australian government wishes to use should phase 3 clinical trials prove successful. This vaccine is based on a modified chimpanzee adenovirus.




Read more:
The Oxford deal is welcome, but remember the vaccine hasn’t been proven to work yet


Two adenovirus based COVID-19 vaccines have been approved for early or limited use internationally. These were developed by the Chinese Academy of Military Medical Sciences with CanSino Biologics and the Gamaleya Research Institute, part of Russia’s health ministry.




Read more:
Russian coronavirus vaccine results have been published – here’s what they reveal


3. Inactivated

Inactivated vaccines are a tried and trusted method of vaccination. It’s the technology used in the vaccine against poliovirus and in some types of flu vaccines. Inactivated vaccines contain viruses treated with heat, chemicals, or radiation so they cannot replicate, but can still trigger an immune response.

Pros

Cons

  • low immunogenicity, so requires multiple boosters.

The Chinese government has granted emergency approval for limited use of an inactivated COVID-19 vaccine developed by Sinovac Biotech.

4. Live-attenuated virus

Live-attenuated vaccines are among the most successful existing vaccine strategies, already used to protect against measles and polio. These contain virus weakened in the lab. The virus is still viable (live) but cannot cause disease. After vaccination, the viruses in these vaccines grow and replicate, stimulating an excellent immune response.

Pros

  • strong protection as vaccine mimics the natural infection process

  • cost effective for large-scale manufacturing with a familiar regulatory approval pathway

  • single immunisation without needing extra molecules (adjuvants) to stimulate the immune system.

Cons

  • very rare potential to revert to a disease-causing state

  • limited use in people with weakened immune systems due to potential safety concerns

  • can require cold storage, which may limit potential for distribution.

Several live-attenuated COVID-19 vaccine candidates are currently in preclinical trials.

Our group, at Griffith University, has partnered with vaccine manufacturer Indian Immunologicals Ltd to develop a live-attenuated COVID-19 vaccine.




Read more:
Could BCG, a 100-year-old vaccine for tuberculosis, protect against coronavirus?


5. Protein subunit

Subunit vaccines do not contain live components of the virus, but are made from purified pieces of the virus (protein antigens) that trigger an immune response. Again, this is an existing technology, used for instance in hepatitis B vaccines.

Pros

  • with no live components, subunit vaccines are generally thought to be safe

  • can be used in people with weakened immune systems and other vulnerable populations.

Cons

  • the protein antigens that best elicit an immune response must be investigated in detail

  • can stimulate an insufficient immune response meaning that protection is likely to require multiple boosters or for the vaccine to be given with an immune system stimulant.

The University of Queensland has developed a protein subunit vaccine for COVID-19 that is being combined with an immune stimulant made by CSL. It is another one of the vaccines Australia wishes to use, should phase 3 clinical trials prove successful.




Read more:
Putting our money on two COVID vaccines is better than one: why Australia’s latest vaccine deal makes sense


In a nutshell

Not all vaccines currently being developed to prevent COVID-19 will be successful. Safety issues or a lack of protection will halt some.

So, a broad portfolio of vaccine approaches and technologies is progressing through human trials is reassuring. We don’t want to put all our eggs in one basket.

Ultimately, it is likely we’ll need a repertoire of COVID-19 vaccines to offer widespread protection. Different vaccine formulations will ensure vaccination is safe and effective for all members of society, including infants, the elderly and people with weakened immune systems.




Read more:
5 ways our immune responses to COVID vaccines are unique


The Conversation


Suresh Mahalingam, Principal Research Leader, Emerging Viruses, Inflammation and Therapeutics Group, Menzies Health Institute Queensland, Griffith University and Adam Taylor, Early Career Research Leader, Emerging Viruses, Inflammation and Therapeutics Group, Menzies Health Institute Queensland, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

View from The Hill: Why not have an inquiry to examine the pros and cons of suppression versus elimination?


Michelle Grattan, University of Canberra

Scott Morrison on Wednesday once again ruled out any consideration of moving to an “elimination” strategy for dealing with COVID-19.

He told Triple M Melbourne: “You don’t just shut the whole country down because that is not sustainable.

“There’d be doubling unemployment, potentially, and even worse.

“The cure would be worse than what arguably wouldn’t be delivered anyway, because as we’ve seen with the outbreak in Victoria, it came from a breach of quarantine.

“So unless we’re going to, you know, not allow any freight or any medical supplies into Australia or not allow any exports or anything like this, there is always going to be a connection between Australia and the rest of the world.”

Morrison’s sentiments were backed by the business lobbies. Innes Willox, head of the Australian Industry Group, praised the prime minister for “calling out the prohibitive costs” of an elimination strategy.




Read more:
Lockdown, relax, repeat: how cities across the globe are going back to coronavirus restrictions


This would mean closing ourselves off from the rest of the world “indefinitely” and require “draconian restrictions” on citizens and businesses, Willox said.

NSW premier Gladys Berejiklian, commenting on the NSW outbreak, also eschewed an elimination strategy.

Even if they are all correct in rejecting elimination, they haven’t properly addressed the arguments, or produced enough evidence to back their assertions.

Instead the government at least – excuse the pun – has sought to suppress the debate about elimination.

Morrison said there would be a “doubling” of unemployment, or worse. Could we have the figures underpinning this please?

At present, in all states and territories apart from Victoria and NSW the virus is effectively or nearly eliminated. So what would happen to unemployment in those states? Maybe a small tick up but you wouldn’t think a lot.

Victoria is once again shut down – triggering more unemployment under the current suppression strategy.

Presumably the treasury could produce some numbers to shed light on the prime minister’s claim.

Morrison’s statement that an elimination strategy would not allow any freight or medical supplies into Australia nor “allow any exports” smacks of exaggeration (at the least). Maximum care would be needed but border issues regarding crews are being managed now.

Willox says elimination would mean closing ourselves off to the rest of the world “indefinitely”.

The first point to be made is that, in terms of the movement of people, we are already closed internationally, apart from those coming home or foreigners leaving. This closure has no end date.

Secondly, after elimination presumably the border could eventually be open to a greater or lesser extent, with a very strict quarantine system.

Morrison’s claim that pursuing elimination would mean shutting down the whole country seems hyperbolic, when we already have extensive elimination. Apart from that, where shutdowns may be needed there can be a trade off – you can have a less severe shutdown but keep some restrictions for longer.

Admittedly, if elimination were successful there would be the danger of complacency, but we’ve seen this under suppression.

Elimination doesn’t mean there will never be cases. It means they are few enough for potential community transmission to be quickly dealt with.

Health experts are divided over whether elimination would be worth pursuing. Victoria’s chief health officer Brett Sutton said on Wednesday: “I’d love elimination. We’re not at a point where it’s the right time to make a detailed consideration of its feasibility, but … it’s worthy of consideration. There’s no question that it’s got its own challenges, but it’s got its benefits as well.”




Read more:
More deaths in Victoria, as NSW COVID cluster triggers reactions in Queensland and South Australia


Nick Talley, editor-in-chief of the Medical Journal of Australia, a physician and an epidemiologist, believes elimination would be the best strategy for both the society and the economy.

“We eliminated the virus – almost by accident – in large parts of the country during the last lockdown. I suspect this was in part because most of the cases were from international travellers who could be traced and isolated – there was limited community transmission.

“This is very different from the current outbreak in Victoria, and possibly NSW, because there is extensive community transmission,” Talley says.

“I’m not convinced the suppression strategy is going to work. If we don’t eliminate the virus the economy won’t be able to fire up across the country.”

The multiple federal medical officers have backed suppression. Aware of the government’s firm view, they do not freelance.

Both Morrison and Berejiklian have condemned in principle having a stop-start situation. But neither is saying Victoria should have stayed open through its current second wave.

While Morrison and business point to the potential costs of elimination, are they talking short term or long term costs?

For example, New Zealand’s elimination policy is projected to impose a greater economic hit than expected in Australia. But the difference might be somewhat lessened by the second Victorian shutdown, and narrowed further if there are future stop-starts.

It may be that elimination is not the way to go. But why not, say, have a short sharp inquiry, to gather evidence on the health and economic implications, so we know more about the options?

Actually we know why not. The government does not want its course seriously contested.The Conversation

Michelle Grattan, Professorial Fellow, University of Canberra

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When a virus goes viral: pros and cons to the coronavirus spread on social media



Tim Gouw/Unsplash, CC BY

Axel Bruns, Queensland University of Technology; Daniel Angus, Queensland University of Technology; Timothy Graham, Queensland University of Technology, and Tobias R. Keller, Queensland University of Technology

News and views about coronavirus has spread via social media in a way that no health emergency has done before.

Platforms like Twitter, Facebook, Tik Tok and Instagram have played critical roles in sharing news and information, but also in disseminating rumours and misinformation.

Getting the Message Out

Early on, snippets of information circulated on Chinese social media platforms such as Weibo and WeChat, before state censors banned discussions. These posts already painted a grim picture, and Chinese users continue to play cat and mouse with the Internet police in order to share unfiltered information.

As the virus spread, so did the social media conversation. On Facebook and Twitter, discussions have often taken place ahead of official announcements: calls to cancel the Australian Formula One Grand Prix were trending on Twitter days before the official decision.

Similarly, user-generated public health explainers have circulated while official government agencies in many countries discuss campaign briefs with advertising agencies.

Many will have come across (and, hopefully, adopted) hand-washing advice set to the lyrics of someone’s favourite song:

Widespread circulation of graphs has also explained the importance of “flattening the curve” and social distancing.

Debunking myths

Social media have been instrumental in responding to COVID-19 myths and misinformation. Journalists, public health experts, and users have combined to provide corrections to dangerous misinformation shared in US President Donald Trump’s press conferences:

Other posts have highlighted potentially deadly assumptions in the UK government’s herd immunity approach to the crisis:

Users have also pointed out inconsistencies in the Australian cabinet’s response to Home Affairs Minister Peter Dutton’s coronavirus diagnosis.

The circulation of such content through social media is so effective because we tend to pay more attention to information we receive through our networks of social contacts.

Similarly, professional health communicators like Dr Norman Swan have been playing an important role in answering questions and amplifying public health messages, while others have set up resources to keep the public informed on confirmed cases:

Even just seeing our leaders’ poor hygienic practices ridiculed might lead us to take better care ourselves:

Some politicians, like Australian Prime Minister Scott Morrison, blandly dismiss social media channels as a crucial source of crisis information, despite more than a decade’s research showing their importance.

This is deeply unhelpful: they should be embracing social media channels as they seek to disseminate urgent public health advice.

Stoking fear

The downside of all that user-driven sharing is that it can lead to mass panics and irrational behaviour – as we have seen with the panic-buying of toiletpaper and other essentials.

The panic spiral spins even faster when social media trends are amplified by mainstream media reporting, and vice versa: even only a handful of widely shared images of empty shelves in supermarkets might lead consumers to buy what’s left, if media reporting makes the problem appear much larger than it really is.

News stories and tweets showing empty shelves are much more news- and share-worthy than fully stocked shelves: they’re exceptional. But a focus on these pictures distorts our perception of what is actually happening.

The promotion of such biased content by the news media then creates a higher “viral” potential, and such content gains much more public attention than it otherwise would.

Levels of fear and panic are already higher during times of crisis, of course. As a result, some of us – including journalists and media outlets – might also be willing to believe new information we would otherwise treat with more scepticism. This skews the public’s risk perception and makes us much more susceptible to misinformation.

A widely shared Twitter post showed how panic buying in (famously carnivorous) Glasgow had skipped the vegan food section:

Closer inspection revealed the photo originated from Houston during Hurricane Harvey in 2017 (the dollar signs on the food prices are a giveaway).

This case also illustrates the ability of social media discussion to self-correct, though this can take time, and corrections may not travel as far as initial falsehoods. The potential for social media to stoke fears is measured by the difference in reach between the two.

The spread of true and false information is also directly affected by the platform architecture: the more public the conversations, the more likely it is that someone might encounter a falsehood and correct it.

In largely closed, private spaces like WhatsApp, or in closed groups or private profile discussions on Facebook, we might see falsehoods linger for considerably longer. A user’s willingness to correct misinformation can also be affected by their need to maintain good relationships within their community. People will often ignore misinformation shared by friends and family.

And unfortunately, the platforms’ own actions can also make things worse: this week, Facebook’s efforts to control “fake news” posts appeared to affect legitimate stories by mistake.

Rallying cries

Their ability to sustain communities is one of the great strengths of social media, especially as we are practising social distancing and even self-isolation. The internet still has a sense of humour which can help ease the ongoing tension and fear in our communities:

Younger generations are turning to newer social media platforms such as TikTok to share their experiences and craft pandemic memes. A key feature of TikTok is the uploading and repurposing of short music clips by platform users – music clip It’s Corona Time has been used in over 700,000 posts.

We have seen substantial self help efforts conducted via social media: school and university teachers who have been told to transition all of their teaching to online modes at very short notice, for example, have begun to share best-practice examples via the #AcademicTwitter hashtag.

The same is true for communities affected by event shutdowns and broader economic downturns, from freelancers to performing artists. Faced with bans on mass gatherings, some artists are finding ways to continue their work: providing access to 600 live concerts via digital concert halls or streaming concerts live on Twitter.

Such patterns are not new: we encountered them in our research as early as 2011, when social media users rallied together during natural disasters such as the Brisbane floods, Christchurch earthquakes, and Sendai tsunami to combat misinformation, amplify the messages of official emergency services organisations, and coordinate community activities.

Especially during crises, most people just want themselves and their community to be safe.The Conversation

Axel Bruns, Professor, Creative Industries, Queensland University of Technology; Daniel Angus, Associate Professor in Digital Communication, Queensland University of Technology; Timothy Graham, Senior Lecturer, Queensland University of Technology, and Tobias R. Keller, Visiting Postdoc, Queensland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.