In April I wrote a piece entitled “The Search for a Vaccine” which detailed the science behind vaccine development. At that time there were 47 ongoing COVID-19 vaccine trials worldwide, there are now 133. (1a)
Of these, two trials in particular are rapidly progressing, one in Oxford in the UK and the other in the USA.
(For a further explanation of types of vaccines and the different trial phases please click here for my previous piece.)
The Oxford University Vaccine Study.
The Jenner Institute (University of Oxford) and the Oxford Vaccine Group are developing a vaccine that targets the club-shaped spikes seen on the surface of the virus.
Researchers have isolated the genetic code of these surface spikes and have been able to attach that code to a known harmless virus which then starts to make the spikes itself. This forms the basis of the vaccine and once injected into the body the immune system believes it is the genuine coronavirus and attacks it.
The vaccine has passed the initial Phase I safety trial and recruitment for a combined Phase II and III trial has begun. However, researchers are struggling to find enough volunteers for their human trials. Ironically, as the number of cases of COVID-19 has declined in the UK it has become harder to recruit the 10,000 people needed for the trials. This is because as transmission of the virus reduces, more participants will be needed.
The premise of any vaccine trial is that volunteers are split into two groups, one which receives the vaccine and one that does not. Both groups are exposed to the illness in their day to day lives and are monitored to see who develops the disease. The two groups can then be compared with each other.
(Contrary to popular belief, trial participants are not deliberately infected with COVID-19. Although this approach, known as Challenge Trials, is sometimes used it is only done so when there is a wealth of knowledge about the illness and well established treatments that will successfully treat any subsequent illness. Neither of these two parameters apply to COVID-19.)
It can take many months for enough people to be exposed to the illness for any results to be reliable. As the infection rate falls, fewer of the volunteers are likely to be exposed to the virus as there is simply less of it around. One solution to try and mitigate this is to recruit a greater number of volunteers to increase the chance that enough of them are exposed to the virus. One option may be to extend the study into places that still have high infection rates such as South America. (1b)
Professor Adrian Hill of Oxford University explains, “It’s a race against the virus disappearing, and against time. We said earlier in the year that there was an 80% chance of developing an effective vaccine by September. But at the moment, there’s a 50% chance that we get no result at all.” (2) (3)
Initial animal studies on the vaccine showed that it did not stop monkeys contracting the virus, but did appear to prevent them from becoming ill and in particular from developing pneumonia, a major cause of death in COVID-19 patients. If humans react in the same way it is possible that the vaccine will not stop people from catching COVID-19 but will ensure that if they do it will be in a milder form. (4)
The British-Swedish pharmaceutical company AstraZeneca has signed an agreement with Oxford University and will be responsible for the development and worldwide manufacturing and distribution of the vaccine. Despite recognising that the vaccine may fail in the current trials, the company has committed to manufacturing an initial 1 billion doses if the human trials are successful. (5) (6) (7)
The US Vaccine Study.
The vaccine being developed by the US company Moderna has passed its initial human safety trials. Preliminary studies showed that 8 out of 45 people who received the vaccine developed antibody levels similar to those found in patients who had recovered from COVID-19. However this means 37 people did not develop antibodies and the data so far released does not make clear if the antibodies produced by the vaccine would be protective against infection.
If successful, the Moderna vaccine will be the first mRNA vaccine licenced for use in humans. Previous attempts to make mRNA vaccines have failed to elicit immunity in humans despite working across a diverse range of animals from fish and birds to horses. (8)
Moderna is now recruiting for its Phase II trial for which it wants 600 participants from across at least 10 different states. It will follow these volunteers for 15 months. (9)
Experts are expressing concern about the limited amount of data Moderna has so far released. Anna Durbin, a vaccine researcher at Johns Hopkins University, explained that it was not possible to interpret the sparse data saying, “I do think it’s a bit of a concern that they haven’t published the results of any of their ongoing trials that they mention in their press release. They have not published any of that.”
And John Rose, another vaccine researcher from Yale University said the company needed to publish its information commenting that, “When a company like Moderna with such incredibly vast resources says they have generated SARS-2 neutralizing antibodies in a human trial, I would really like to see numbers from whatever assay they are using.” (10)
Moderna has also made clear that it will be working closely with the US government in deciding who receives the vaccine.
Stephan Bancel, the CEO of Moderna, said that the company will “collaborate with the U.S. government to determine who receives the first dose.” (11)
In Conclusion.
It is possible that the first COVID-19 vaccine may not necessarily prevent infection but mitigates against the severity of infection which would still be a significant benefit. It is possible that booster doses of this vaccine will confer immunity in the long run or that another vaccine candidate will eventually come along and replace it but it is simply too soon to know.
