Hunting for a vaccine
Oxford boffins lead the pack
● Nearly two centuries ago, Edward Jenner inoculated an eight-year-old boy with pus from cowpox blisters taken from a milkmaid. The boy miraculously developed protection from smallpox, thus pioneering the field of vaccinology. Today, the Jenner Institute, based at Oxford University, lives up to its namesake.
Scientists here have made the fastest strides in developing a vaccine for Covid-19. This was partly spurred by the laboratory’s experience with vaccine development, including one developed last year against the Middle East respiratory syndrome (Mers) coronavirus that was shown to be safe in humans.
About a third of the world is under lockdown as a public health measure to curb viral transmission, though the balance between further disease spread and socioeconomic costs is highly debated. The approach of governments to easing the lockdown rests on ramping up the World Health Organisation’s policy of isolation, testing and tracing, returning to work based on specific risk factors, new or repurposed treatment and, lastly, vaccination.
For society to return to “normal” any time soon, our best shot is an effective vaccine. This could also be accomplished by a miracle treatment with at least
95% efficacy that stops the virus, but this is unlikely within a short timeframe, given the complexity of the process and highly adaptive ability of the virus. Drug candidates such as Remdesivir, the first authorised drug treatment for Covid-19 in the US, may be able to save many lives, but it will clearly be insufficient to halt the spread of the pandemic.
Oxford’s experimental vaccine, “ChAdOx1 nCoV19”, is in phase I/II of clinical trials, in which testing since the end of April has begun on more than 1,000 healthy volunteers. The study aims to assess whether the vaccine can protect healthy participants from Covid-19. It will also provide us with valuable safety information and generate data, letting us know if the body is able to produce a good immune response against the virus.
The experimental vaccine is made from a virus named “ChAdOx1”, which is a weakened version of the common cold virus, an adenovirus that infects chimpanzees that has been genetically modified so that it is impossible to grow in humans. Genetic material taken from the Covid-19 virus used to make proteins called Spike glycoproteins is added to the “ChAdOx1” virus, which results in the vaccine candidate “ChAdOx1 nCoV-19”. These Spike proteins are generally found along the surface of the Covid-19 virus and create an image on the electron microscope that resembles a “solar corona”, from which the name coronavirus derives.
These Spike proteins — by binding to receptors called ACE2 on human cells — play an important role in the virus gaining entry and causing infection. The vaccine allows the body to recognise and develop an immune response to the Spike proteins, thereby blocking the virus from entering the human cell, preventing an infection. Thus far, vaccines made from ChAdOx1 have been shown to be safe and well tolerated, with only minor symptoms such as fever, headache or sore arm.
It is necessary for a small number of participants to develop Covid-19 in this study, which depends on the level of viral transmission in the community. If viral transmission remains high, evidence of the efficacy of the vaccine will be available by June.
In an independent study conducted in Montana in the US, six rhesus monkeys were given the same experimental coronavirus vaccine from Oxford and did not catch Covid-19 after heavy exposure, raising hopes for the human vaccine.
However, some experts caution that we may not find an effective and safe Covid-19 vaccine, as in the case of HIV and malaria, where years of research have been invested without substantive reward.
And designing an effective and safe vaccine is only part of the challenge. Vaccine manufacture and distribution is no easy task, especially in the midst of a raging pandemic. To do this so that a vaccine reaches you and me before the natural cessation of a pandemic is a feat that has never been accomplished in history. Researchers and health authorities around the globe are finding innovative ways to compress a 10-year process into 10 months, and some are rightfully worried about balancing this with patient safety.
At least 60% of the world’s population would need to have protective immunity against this virus to achieve herd immunity, the concept of protection from an infectious disease that occurs when a large percentage of the population becomes immune to the disease. This translates to at least 5-billion doses of the vaccine, to be distributed to every corner of the world, a mammoth task at the very least.
Currently there are more than 100 candidate vaccines in the pipeline at various stages of development, of which at least six are being tested in human trials. Production has already started for vaccines at the forefront of the race. The financial risk of not producing vaccines now far outweighs the risk of producing vaccines proven to be ineffective later.
If early vaccine efficacy is shown, Oxford, in partnership with pharmaceutical giants AstraZeneca and the Serum Institute of India, will produce, respectively, at least 1-million, and between 20million and 40-million doses, by September. Other pharmaceutical companies may soon follow suit.
Professor Adrian Hill, the director of the Jenner Institute, has made it clear that should this vaccine work, no-one should reap extra profit from this and everyone around the globe should have equitable access, leaving no developing country behind. But the reality is that it would be extremely difficult for any vaccine made in one’s own country to be exported without first ensuring its own citizens are protected.
Africa has about 17% of the world’s population, but 0.1% of the world’s vaccine production. The Coalition for Epidemic Preparedness Innovations says there are, alas, no laws forcing countries to share vaccines fairly.
The Bill and Melinda Gates Foundation has recently pledged an additional $50m in funding for the Global Alliance for Vaccines and Immunisation towards efforts to distribute future Covid-19 vaccines to lowincome countries. However, further local efforts and home-grown innovative solutions are required.
Moreover, there is a need for increased vaccination trials with the utmost safety to be conducted in Africa on Africans to understand how our bodies respond to these vaccines, which may differ from populations tested elsewhere due to genetic variances.
The world has never been in a better position, at least scientifically, to deal with a pandemic of such a nature. As the wealthy isolate in their holiday homes and the middle class balance work and taking care of restless kids from home, the poorest still have to show up for work in essential jobs and worry about their daily income.
If there is a vaccine, we need to ensure the most vulnerable in society receive it first.