It’s still too early to celebrate the success of the coronavirus vaccine story.
While the results of the initial phases of human trials of COVID-19 vaccine, developed by the Oxford University, are promising, it is still a long way to go before it is considered safe to be given to the public.
The initial findings of the randomised trials, involving 1,077 people, showed that the injection had produced antibodies and T-cells, a type of white blood cells which coordinate the immune system. Also, there were no major side-effects, according to the findings published in the medical journal, The Lancet.
While this is hugely promising, the key question remains whether the vaccine, developed by Oxford University’s Jenner Institute and licensed to AstraZeneca, a multinational pharmaceutical company, can either prevent people from becoming ill or even lessen their symptoms of COVID-19. It is not clear whether the level of antibodies and T-cells produced was enough to prevent the disease.
“This is an early-stage clinical trial. One cannot comment on the long-term efficacy because they have not followed up patients long enough,” Dr Trivadi Ganesan, a senior clinical researcher, told The Federal.
However, the trials have elicited an encouraging initial response in terms of increase in antibodies and T-cells that will help fight the virus and prevent it from multiplying, said Dr Ganesan, who was a consultant Medical Oncologist at the Churchill Hospital at Oxford.
“We have to wait for long term efficacy because we don’t have enough data. The third phase trials need to demonstrate this and it is going to take time,” the scientist said.
Larger study needed
The Phase III trials, involving a large sample across multiple countries, will help establish the safety and efficacy of the vaccine, developed by researchers using a genetically engineered virus that causes the common cold in chimpanzees.
The next trial will involve more than 30,000 people in the United States, 10,000 in the UK, 2,000 in South Africa and 5,000 in Brazil. The objective of this crucial phase of the trial is to see if the immune response seen in the early stages protects against COVID-19.
It will also help researchers assess how the vaccine works in a large number of people over the age of 18, and how well the vaccine works to prevent people from becoming infected. It will also confirm their findings in different groups of people, those with other health conditions and in ethnically and geographically diverse populations.
“There is still much work to be done before we can confirm if our vaccine will help manage the COVID-19 pandemic. We still do not know how strong an immune response we need to provoke to effectively protect against Sars-Cov-2 infection,” Prof Sarah Gilbert from the University of Oxford said.
Another member of the research group, Prof Andrew Pollard, said, “We’re really pleased with the results published today as we’re seeing both neutralising antibodies and T-cells.”
“They’re extremely promising and we believe the type of response that may be associated with protection. But, the key question everyone wants to know is does the vaccine work, does it offer protection… and we are in a waiting game.”
The Lancet report said the study showed 90 per cent of people developed neutralising antibodies after one dose. Only ten people were given two doses and all of them produced neutralising antibodies.
How does the vaccine work?
The vaccine – called ChAdOx1 nCoV-19 – is made from a genetically engineered virus which was modified to mimic coronavirus in its appearance. The researchers did this by transferring the genetic instructions for the coronavirus’s “spike protein” — the crucial tool it uses to invade human cells — to the vaccine they were developing.
This means the vaccine resembles the coronavirus and the immune system can learn how to attack it.
The vaccine developed by the Oxford researchers, tries to build the body’s immunity against a spike protein. The spikes on the surface of coronavirus is the reason why the virus easily spreads in the body. The intention is to create antibodies to fight this spiked surface so that the virus does not get a chance to penetrate the cells.
A weakened common cold virus called adenovirus was used to make the spiked protein. When the vaccine is injected, the body starts building antibodies against this protein, which will help fight coronavirus.
The World Health Organization (WHO) has described the Oxford vaccine as the leading candidate in the global fight to halt the coronavirus pandemic. AstraZeneca has signed agreements with governments around the world to supply the vaccine, once it is proved effective and gets regulatory approval.
The pharma giant also entered a deal with Pune-based Serum Institute of India to supply one billion doses for low-and-middle-Income countries, with the first 400 million doses before the end of 2020.
It takes years, if not decades, to develop a vaccine. However, researchers across the world are now virtually racing against time to achieve the goal in only a few months. Most experts think a vaccine is likely to become widely available by mid-2021, about 12-18 months after the new virus, known officially as Sars-CoV-2, first emerged.
There are nearly 140 vaccine candidates that are in the pre-clinical stage while ten candidates have reached Phase II which involves expanded safety trials.
Along with the Oxford vaccine, two more research groups in the US and China reported similar encouraging results after initial trials. American biotech company Moderna was the first to initiate human trials to test its vaccine.
A COVID-19 vaccine developed by CanSino Biologics Inc and China’s military research unit has shown to be safe and induced immune response in most of the recipients. The CanSino candidate, named Ad5-nCOV, is one of a handful of vaccines that have shown some promise in human testing and are gearing up for late-stage trials.
While CanSino’s vaccine has yet to start late-stage large-scale clinical trials to assess how well it works to prevent people from becoming infected, it has received the green light to be used in China’s military.
US companies BioNtech and Pfizer have also reported positive results using their RNA vaccine.