The University of Oxford and AstraZeneca Plc.’s experimental vaccine is the first to enter the final stages of clinical trials to assess how well it works in protecting people from becoming infected by the virus that causes the coronavirus disease (Covid-19), which has infected 9.4 million and killed 480,000 globally since late December.
The ChAdOx1 nCoV-19 vaccine, which has been licenced to AstraZeneca, will be given to 10,260 adults and children in the next stage in the UK. The vaccine is also being trialled in South Africa and Brazil, with Serum Institute of India (SII) investing $100 million to mass-produce one billion doses for India and other low-and-middle-income countries.
The vaccine is made from the ChAdOx1 virus, which is a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees; it has been genetically changed so it can’t cause infection in humans.
“The clinical studies are progressing very well and we are now initiating studies to evaluate how well the vaccine induces immune responses in older adults, and to test whether it can provide protection in the wider population,” said Professor Andrew Pollard, head of the Oxford Vaccine Group, in a statement on Wednesday.
If the trial is successful, the Oxford Vaccine Group expects to launch the Covid-19 vaccine by the end of this year, which will make it the fastest vaccine to progress from lab to getting regulatory approval for use.
The Oxford Vaccine Group is not the only group to move to a vaccine at warp speed. The pace of vaccine development is accelerating with each passing week with companies from around the word racing to be the first to develop an effective vaccine to stop or at least slow the spread of Covid-19.
There were 13 experimental vaccines in clinical trials and another 129 in the preclinical evaluation stage on June 22, according to the World Health Organisation’s draft landscape of Covid-19 vaccines. On June 12, there were 10 in advanced clinical trials and 115 in preclinical evaluation stages.
Vaccine development, on average, takes 10.71 years from the preclinical phase, and has a success rate of 6%, according to a study in the science journal, PLOS One. Some remain elusive for decades despite massive investments, like for vaccines against HIV, the virus that causes AIDS.
Vaccines from US-based Moderna Inc. and China’s Sinovac Biotech a will enter the final stage of trials next month, and Beijing-based China National Biotec Group Co. is the latest to receive regulatory approval to conduct phase 3 trials of its Covid-19 vaccines in the United Arab Emirates on Tuesday.
Four vaccine candidates Indian companies are partnering to develop are in the preclinical trial stages to test their pharmacological effect and toxicity, with five companies in the fray. Delhi-based Panacea Biotec is partnering with Refana Inc. in the US to develop an inactivated whole virus vaccine, Hyderabad-based Bharat Biotech is working on three vaccine candidates using two different platforms in the works, including one that uses an existing nasal flu vaccine, and SII has three partnerships with Oxford-AstraZeneca, US-biotech firm Codagenix, and Austria’s Themis Bioscience. Zydus Cadila in Ahmedabad and India Immunologicals in Hyderabad have also formed partnerships to develop Covid-19 vaccines.
While a fast-tracked vaccine development process could have a vaccine for emergency use ready by early 2021, safety must not be compromised in the rush to reach the finish line, experts cautioned.
“The dengue vaccine (Dengvaxia) controversy in the Philippines should be a grim reminder of the dangers of rushing ahead without safety checks in place. Philippines suspended its school-based dengue vaccination programme using Sanofi Pasteur’s Dengvaxia vaccine following reports of vaccination-related deaths. The company then cautioned that the vaccine carried higher risk for people without prior dengue infection,” said Dr N K Ganguly, former director general, Indian Council of Medical Research.
Vaccination of healthy people carries a risk of subsequent Sars-CoV2 infection becoming more severe, as has happened before with vaccines including a coronavirus-unrelated respiratory virus in children, according to a paper published in Science on May 29.
Vaccine development includes at least three human trials to test their safety, dosage and the strength and duration of the protection they offer, followed by production, licensing, deployment and plans for post-marketing surveillance. Many of these trials have been collapsed and merged in the case of Covid-19 to have a vaccine ready for use by early 2021.
“With promising preliminary preclinical and phase 1 data available, meticulously planned trials are needed to separate the contenders from pretenders. Post-marketing data on adverse reactions is vital to measure the benefits in a large population, 60% of whom may develop some amount of herd or community immunity over the next two years that would help reduce transmission,” said Dr Ganguly.
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