There is a phenomenal amount of work going on right now to find a vaccine for COVID-19. No fewer than 200 vaccine candidates are being looked at. Sixteen of these are already being tested in humans. This is a huge number when we consider it is not even a year into the pandemic and vaccines have previously taken up to a decade to develop! Here is a list of the sixteen that are being studied in clinical trials. This list was taken from a complete list of all 200 vaccine candidates published by the WHO.

Read “How do vaccines work?” before continuing.

COVID-19 Vaccines Already in Clinical Trials

You can look at the details of each clinical trial that is ongoing by following the links in the table. Let’s look at the various types of vaccines being tested.

1. Inactivated virus. This is a traditional method of creating a vaccine. You take a sample of the virus from sick patients, you culture it and then you find a way of inactivating it, i.e. stopping it from causing sickness, but not killing it. An example of this is explained in detail in this link. In people without a fully functioning immune system this can still cause disease. Thus people with blood cancer are not able to take these vaccines. An example of this kind of vaccine is the traditional shingles vaccine.
2. Protein Here you take a part of the virus and synthesise a protein that forms part of the structure. This protein is called an antigen and it stimulates the production of antibodies with zero risk that it can produce sickness. This type of vaccine does not pose a risk to those who have a damaged immune system, although like all vaccines it might not cause a response in those patients. An example of this is the new shingles vaccine, Shingrex, which is available in the USA, but whilst it is officially licensed in Europe it is mostly only available privately and supply is restricted.
3. DNA Here you take a part of the genetic code that is included in the virus which codes for the protein you want to create antibodies for. Often viruses actually contain RNA not DNA so you actually have to create the corresponding DNA that will then be copied by the body’s own cells to first create the RNA then that will be decoded to create the protein. Thus the body itself effectively becomes the factory for the vaccine. There have been some concerns that DNA vaccines might lead to the DNA being permanently included into the human cells genome. One other issue with a DNA virus is how do you protect the DNA when you inject it into the body, and how do you make sure that it is taken up into human cells so that it can create the protein. Whilst there has been a lot of work done on DNA vaccines none of them have yet been fully developed and released.
4. RNA Here you take a portion of the RNA code of the virus that codes for the protein that you want to form antibodies against. You then simply inject that RNA snippet directly into a human in the hope that it will be taken up by human cells and as a result the viral protein would be created. The issue with RNA vaccines is that they can be fragile, and not always be able to be taken up by the body cells. Again none of these have yet been fully developed and released.
5. Non replicating Viral Vector This is how the Oxford university vaccine plug and play vaccine platform works. You take a virus that cannot cause sickness in humans, in this case a virus that causes the common cold in chimpanzees, and then modify it to ensure it cannot grow inside human cells. You can then use that virus as an envelope to contain and protect the RNA strand you want to deliver. The virus will also deliver and insert the RNA into some human cells so they will then produce the corresponding protein antigen (lock) prompting the body to respond by creating the correct antibodies (key).

The viral vector is a very new approach and it is relatively easy to create a new vaccine candidate using it, as evidenced by the fact Oxford University were able to create their vaccine candidate as early as January 2020. This vaccine method seems to be in the lead currently and looks like it may well be the first to have results from its major clinical trials some of which have already concluded enrolment.

At this point it is not 100% clear whether people who are immune compromised will be able to use this type of vaccine or not. Whether we can or not we will benefit from the resulting herd immunity if it does work. Whilst it is technically a live vaccine if it really cannot cause any disease in humans and is not capable of growing inside the human body it would logically that perhaps it might be safe to be used by blood cancer patients, unlike traditional live vaccines. So far clinical trials have not included immune compromised individuals but this seems to be due to a concern that they might not respond to the virus rather than a safety risk.

It is interesting to note that there are several other vaccine candidates that also use a virus vector. Before COVID19 this new adenovirus platform was a novel scientific marvel waiting for an opportunity to really show its worth. Having said that it does look like this platform could turn out to be a major innovation in medicine. In news that seems to have been somewhat swallowed up by COVID19 the Oxford vaccine platform showed some activity in Prostrate cancer.

In cancer the idea is to use the virus platform to induce the body to create an antigen found on the surface of its own cancer cells. Therefore we could potentially cause the immune system to effectively turn on the cancer and hopefully destroy it. Imagine if we could be vaccinated against our own cancer?

Could this also work for blood cancer? Since we already target proteins on the surface of blood cancer cells with antibodies like rituximab it certainly will be very worthwhile exploring this possibility.

It would be rather deliciously ironic that COVID19 which has been so punishing for the blood cancer community might also accelerate the development of this plug and play vaccine platform which just might lead to multiple different blood cancer vaccines. Our bodies might eventually for example be able to effectively produce our own rituximab or an antibody with a different target on blood cancer cells. It is likely that such vaccines might still need to be used in combination with other current treatments, but nonetheless this is a very exciting possibility.

This new vaccine platform is surely a hugely significant development and if the COVID19 vaccine works and further proves the concept then I am sure we will see a lot of interest in this platform. In theory we could then make the body produce antibodies against any cell marker or infectious disease we want it to. So the crucial stage in producing any new vaccine would be choosing which are the best cell markers that identify harmful cells and allow them to be attacked without damaging other cells. The corresponding RNA could then be delivered by the virus envelope.

The Oxford platform has already been used to develop candidate vaccines for other diseases. But other new infections have rarely spread as rapidly or with such deadly effect than COVID19. The effect has been huge not just to the individuals affected but to the economy and to society itself. As such some of the other candidates have not been rushed through to final testing since the diseases became less of a burden than initially feared. The early studies in other diseases do however show that the platform itself seems very promising.

Because this is effectively a “plug and play” vaccine platform which can present to the body the code for any protein fragment we want it to. This is then creates a delivery agent for mRNA to prompt the body’s own cells to produce a protein from a virus or indeed a cancer protein, and effectively our own body becomes a vaccine factory.

It seems that the UK and USA governments believe this Oxford vaccine has a chance of working, and right now tens of millions of doses are being made “at risk” so they might be avaiable for general use in the UK and USA as soon as September depending on the results from the clinical trials. But more of all this in the next post in this series. In the meantime you can read more about the Oxford vaccine elsewhere. Do allow your hope to be stirred, as it is important that we maintain optimism about a future way out of the crisis during this difficult period of the global Coronacrunch.

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