Why It Could Take Years to Beat COVID-19
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Transcript
The race is on to find a vaccine for COVID-19. As of May 2020, 169 potential vaccines are in different stages of development and billions of dollars are being thrown at the problem.
But even if a new vaccine for COVID-19 becomes available tomorrow, it won’t be enough to save us. Here’s why.
Vaccines are like an intense boot camp for our immune system – they work by training the body’s immune cells to recognize and destroy a virus, before they need to fight it in real life.
The principle behind vaccines is simple enough, but developing one is much more complicated.
First, building a vaccine can be easier said than done.
Take the Hepatitis B and C viruses for example – both infect liver cells and cause liver damage.
We have a remarkably effective vaccine for Hepatitis B, but for many reasons we haven’t been able to make a vaccine for Hepatitis C, despite 25 years of research.
But let’s assume that we are able to build a vaccine for COVID-19. The next challenge is to make sure that it is safe.
In 2016, the Philippines launched a campaign for a brand new vaccine against the Dengue virus, called Dengvaxia. By late 2017, it was found that while most people benefited from the dengue vaccine, there were a group of people that had a higher risk of suffering from severe dengue after receiving the vaccine.
It is thought that vaccine behaves differently in people who have been exposed to dengue in the past compared to people who have never been exposed to dengue.
But because of safety concerns, the Dengue vaccine campaign had to be stopped. And this is why vaccines need to go through rigorous testing before they are approved – we need to make sure that they won’t cause harm.
But’s let’s assume that we are able to build a COVID-19 vaccine, and it is found to be extremely safe. The next hurdle is to see whether it is effective.
Some viruses are easy to build vaccines for, some are more difficult. For example, measles is an easy target because it is a stable virus. So 2 doses of a measles vaccine is 99% effective. On the other hand, the influenza virus keeps mutating and behaves like a moving target, so it is much more difficult to vaccinate against. The current flu vaccine is somewhere between 50 to 70% effective, depending on the flu season.
But let’s assume that we are able to build a COVID-19 vaccine, it is safe and 100% effective. The Achilles heel of all vaccines is ultimately whether enough people end up getting it and how long it takes for that to happen. This is where we could see some problems.
Each virus has a different level of contagiousness – and the more contagious the virus, the more people need to be vaccinated to prevent outbreaks.
Take measles for example. It is the most contagious virus on the planet. In a population with no immunity, one person with measles spreads it to 17 other people. Those 17 will then go on to spread to another 17. Within just 5 transmissions, almost one and a half million people would become infected.
This transmission rate is also known as the reproduction number, also represented as R zero. To successfully control measles, we need to vaccinate enough people so that the virus would have nowhere to spread. We can use the reproduction number to calculate this critical vaccination level - for measles, more than 94% of the population would need be immunised to prevent outbreaks.
To really get on top of COVID-19, we would need to find a vaccine and reach this threshold quickly. The best estimate for the reproduction rate of COVID is 3. So the critical vaccination level is 66%. But remember this assumes that we have a 100% effective vaccine. Because no vaccine is a 100% effective, the critical vaccination level is likely to be higher than 66%.
In Australia, we have a population of around 25 million. This would mean more than 16 million vaccines would need to be given out as quickly as possible.
Large numbers of people would need to turn up for a vaccine completely voluntarily. And when they do turn up, we would need efficient vaccine production and distribution systems to give out thousands of vaccines every day.
But we wouldn’t just need high vaccination in Australia – this would need to be achieved globally.
This virus knows no borders. What happens in another country has a domino effect on its neighbours. Travel and export are incredibly important to many economies, including Australia. But these activities also risk spread of COVID from one country to another.
Even if Australia has a very high vaccination rate, it won’t very mean much if our neighbours and trade partners struggle to get the vaccine out to their people. We would need at least two thirds of the entire world’s population to receive the vaccine for us to successfully beat this virus.
Now Australia is arguably a wealthy country with a strong health system. We could probably achieve a minimum vaccination rate of 66%. But what about places in the world that don’t have the luxury of a robust health system. How will these people get access to the vaccine if we ever get one?
We already know that voluntary vaccination rates vary dramatically across the globe. For example, in Australia 73% of people older than 65 got the flu shot in 2018. But in Thailand, that number was only 12%.
We can also expect that in the early stages of vaccine rollout, demand will far outstrip supply. This may cause countries to compete against one another for access, which could slow down efforts to vaccinate people in less wealthy countries.
Even countries that do get hold of the vaccine won’t be able to get it out to the entire population all at once. It is likely that we will see a staged rollout, with first priority for people at high risk of serious illness, like older people, frontline workers and possibly children, before extending the net to people at lower risk.
All of this will lead to the consumption of one very important resource: time. Every week that we stay in lock down means more jobs lost, more businesses that go under and more people that are unable to pay their obligations like rent and mortgages.
So the way I see it, vaccine development is just one part of the equation. The roll out of a safe and effective vaccine could take months.
Now I have no idea what’s going to happen in the future. But I think we could all learn two things:
We need to assume that the world we are living in now is the new normal. A vaccine will not suddenly snap the world back to pre-COVID. We need to expect that even if a vaccine is found, it could take a long time to roll out. So as governments re-open economies around the world, we need to have sustainable measures that allow businesses to operate while still protecting their employees and their customers from exposure to COVID. That could mean avoiding unnecessary face-to-face contact, good hand hygiene and people staying at home if they’re sick.
The second point is that we need start preparing now for a global effort to manufacture and distribute the vaccine if one ever becomes available. That would mean agreements drawn up in advance on how countries will work together, rather than against each other, to get the vaccine out to their people. Governments would need to work in partnership with private companies to figure out how to ramp up production, distribution and delivery so that the vaccine can be rolled out as fast as possible.
COVID has shown us that ultimately we are all in this together. What happens in China or Japan or the US has flow on effects on the rest of the world.
The big question in my mind is whether countries are in a place to work collaboratively on this health crisis. Adversity can bring out the best in us, but can also bring out the worst. Cracks in global relationships were already in play before this pandemic. Will COVID help us overcome these rifts, or will it make them run even deeper?
I’m interested to hear what you think. Do you think we’ll get a COVID-19 vaccine? And do you think the world is ready to work together? Let’s talk about it in the comments.
Thanks for watching and I’ll catch you in the next one
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Video credits
Stock footage, music, sound effects from Envato Elements (affiliate link - helps support the channel): https://1.envato.market/DG60q
Certain vector illustration adapted from https://www.freepik.com/
Everything else by Ankit.
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References and Further Reading
https://academic.oup.com/cid/article/52/7/911/299077
https://www1.racgp.org.au/ajgp/2020/may/mathematics-for-medical-practitioners
https://vac-lshtm.shinyapps.io/ncov_vaccine_landscape/
https://academic.oup.com/jtm/article/27/2/taaa021/5735319
https://www.mayoclinic.org/diseases-conditions/hepatitis-c/expert-answers/hepatitis-c-vaccine/faq-20110002
https://wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/dengue
https://www.who.int/immunization/diseases/dengue/q_and_a_dengue_vaccine_dengvaxia_use/en/
https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/influenza-flu
https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/measles
https://www.sciencedirect.com/science/article/pii/B9780123694089000305
https://www.statista.com/chart/16575/global-flu-immunization-rates-vary/