As confirmed cases of COVID-19 continue to rise, the world is trying to ready itself for a second wave of the pandemic. After emerging from several months of lockdown, many countries are once again facing the possibility of their healthcare systems being overwhelmed.
Although some countries have been able to flatten the infectious curve through mass testing, targeted quarantines, and contact tracing, it is seemingly only a temporary reprieve. Vaccines will still be the best solution to develop widespread herd immunity.
Is There A Vaccine For Coronavirus?
As of writing this article, there are more than 160 vaccines being developed by scientists around the world. Even still, no vaccine is available for coronavirus at this moment. With companies racing to find a solution, it is estimated that vaccines will be available in the global market by June 2021 at the earliest. Here are the latest updates:
- 140+ vaccines are in the preclinical trial stage
- 18 vaccines are in Phase I: testing for safety and dosage
- 12 vaccines are in Phase II, a.k.a. expanded safety trials
- Six vaccines are in Phase III, a.k.a. large-scale efficacy tests
- One vaccine alone has been approved for limited use
Under normal circumstances, vaccines take many years to develop before being approved for mass distribution. The slow process is not only because of scientific bottlenecks, but also largely because of government safety regulations.
In spite of this, the urgent need for a coronavirus vaccine to fight the pandemic is motivating pharmaceutical companies to develop SARS-CoV-2 vaccines in a fraction of the normal time. Governments are also relaxing their regulations to facilitate the development and approval of vaccines.
China is the first country to approve a vaccine for coronavirus – but for limited use only. Developed by CanSino Biologics, a Chinese pharmaceutical corporation, the vaccine was based on an adenovirus known as Ad5. Partnering with the Institute of Biology in China’s Academy of Military Medical Sciences, the vaccine was approved on 25th June 2020 by the Chinese military for a limited use of one year, by soldiers only.
How Will A Vaccine For COVID-19 Be Made?
All vaccines are made according to the basic principles of immunity. During this process, either a less potent or inactive version of a virus is injected into the body and used to coax the immune system to produce antibodies. This happens because the body recognises the virus as a foreign substance, i.e. an antigen, and produces antibodies to fight against it.
Immunity occurs when the long-term memory of the immune system is activated. This means that the next time the same virus invades the body, the immune system will be able to identify and kill it before the virus hijacks the cells and multiplies.
Researchers have identified several ways to produce vaccines against coronavirus. The main objective, and also obstacle, is to ensure the virus isn’t harmful to the body, whilst still making it capable of triggering an immune response.
Weakening The Virus
Many vaccines are actually just weakened versions of an original virus. The idea behind this strategy is to allow the virus to reproduce inside the body at a very slow rate. In this way, your immune system should have sufficient time to react without the body becoming overwhelmed by the virus. Mild symptoms such as fever may occur after vaccination, but this is normal.
This strategy is the common method used for creating vaccines for a wide range of contagious diseases such as measles, mumps, polio, chickenpox, and influenza. Typically, viruses replicate several thousand times inside the cells. However, the weakened viruses in vaccines can only reproduce around 20 times. This is slow enough for the memory B cells of the immune system to establish long-term immunity against the virus.
Life-long immunity can be induced by using weakened viruses in vaccines, and it may only take one or two doses to get the full effect. On the other hand, this strategy is not good for people with compromised immune systems, such as those who are suffering from cancer or have AIDS. Since COVID-19 is particularly lethal to those with preexisting health conditions, it means that this may not be the best route for creating a coronavirus vaccine for the masses.
Inactivating The Virus
Another method researchers are trying is to ‘inactivate’ samples of the coronavirus in order to make vaccines. Chemicals like formaldehyde are used during viral inactivation, whereby a virus is killed either by dry heat or chemical alteration. This method was used to produce vaccines for diseases like Hepatitis A and rabies.
The structure of COVID-19, namely the spikes, necessitates inactivation:
- The viral spikes are proteins that are capable of binding with cellular receptors
- This mediates the fusion of the viral membrane with the cell membranes
- When this happens, the virus injects its genetic material into the host cells
- It can then hijack the resources of the cells in order to create copies of the virus
- This process repeats millions of times, causing the destruction of the host cells
While an inactivated version of coronavirus will still have these spikes, and may still be able to bind with the cell receptors, the genetic materials of the virus will have been rendered impotent through inactivation. This means that the virus will be unable to hijack the resources of the cells. Meanwhile, the immune system will still be able to respond to the viral spikes and create long-term memory.
The main advantage of this approach is that the vaccine can be administered to those who have compromised immune systems. The vaccine also doesn’t cause any mild symptoms of the disease. The main disadvantage of this approach is the need for several doses to achieve immunity.
Using Part Of The Virus
A modified version of inactivating the virus is to use only a part of it in the vaccines. Some vaccines, such as for hepatitis B and human papillomavirus, are produced in this manner. It works when part of the protein covering of the virus is used to stimulate immune response. This process follows the same logic as weakening the virus so that it is less potent, but still effective at triggering our antibodies.
This method could be effective not only because of how it works, but also because it will be safe for those with a weakened immune system, and only two doses would be needed for full immunity.
Other Approaches To Developing A Coronavirus Vaccine
Interestingly, one alternative approach to making a coronavirus vaccine is not creating a specific vaccine for SARS-CoV-2. Instead, researchers are testing whether existing vaccines are able to trigger a general immune response that will simultaneously fight off the coronavirus.
Another approach is to genetically modify certain immune cells to target the virus. Some researchers are also looking into DNA vaccines. This process introduces the body’s tissue to a plasmid, i.e. a DNA molecule that contains the antigen’s DNA sequence, thus triggering an immune response. While this is one of the less popular methods being researched for coronavirus vaccines, DNA vaccines are beneficial because they do not rely on any infectious agent of the virus, they tend to be more stable, and they are also cost-effective and relatively easy to manufacture at scale.
How Long Is The Wait For A Coronavirus Vaccine?
Vaccine development usually takes several years before the final product becomes available on the market. Depending on some factors, like the type of pathogen, demand, funding, and government regulations, the process may either be slowed down or, in the case of COVID-19, expedited.
It may take at least a year from now before coronavirus vaccines become available to the general public. While each phase of vaccine development takes time, some are now being combined in order to speed up the process. The phases are as follows:
- Preclinical Testing: At this stage, the vaccine is administered to animals, such as mice, to see if there is an immune response.
- Phase 1 – Safety Trials: A small number of human volunteers are given the vaccine to test safety and dosage. The immune response of the volunteers is also tested.
- Phase 2 – Expanded Trials: The vaccine is administered to hundreds of people across varying demographics in terms of age, gender, and health conditions, to see if the vaccine affects them differently.
- Phase 3 – Efficacy Trials: The vaccine is administered to thousands of individuals. The researchers then have to wait to determine how many of the vaccinated become infected by the virus. Meanwhile, some volunteers receive a placebo for comparison purposes.
- Approval: The public health regulating agencies of each country review the trial results and then decide whether to approve the vaccine or not. However, considering the urgency of the current pandemic, many countries are likely to give Emergency Use Authorisation for the coronavirus vaccine before formal approval has been given.
Will Everyone Need A Coronavirus Vaccine?
It might be that not everyone needs to be vaccinated against COVID-19. Aside from practicality issues of vaccinating the entire human population, it could be unnecessary. This is because herd immunity could be achieved with just 40%-80% of a population being vaccinated.
Herd immunity protects the weakest in a population, including elderly people, infants, pregnant women, and those who have compromised immune systems. This works because the virus loses new hosts for effective transmissions in a community. Over time, this will decrease the spreading of the virus until it is no longer in circulation.
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