Days after pausing a study on one of the much-watched vaccines against the novel coronavirus (Covid-19), Oxford University has announced that it will be resuming the tests.
The trial on the vaccine developed by Oxford University and British-Swedish multinational pharmaceutical AstraZeneca was paused last week Wednesday after a participant had a suspected adverse reaction in the United Kingdom.
According to a statement from the company, only the trial in the UK has resumed. Trials of the vaccine will, however, remain on hold in the United States pending a US investigation, Reuters reported on Monday.
The company is also conducting trials in the US, Brazil, and South Africa. Kenya also announced it has applied to participate in the Oxford study.
According to a statement by AstraZeneca, an independent investigation into the event was concluded and it advised the UK’s medical regulator the Medicines and Healthcare products Regulatory Agency (MHRA) that it was safe to resume the trial. The MHRA concurred and gave the green light for the trial to restart.
The illness that triggered the international pause, which occurred in a woman who was in the vaccine arm of the UK trial, has not been officially disclosed, though AstraZeneca CEO Pascal Soriot told a group of investors on Wednesday that her symptoms were consistent with transverse myelitis, a serious condition involving inflammation of the spinal cord that can cause muscle weakness, paralysis, pain and bladder problems, American health-oriented news website Stat News reported.
Oxford and AstraZeneca, however, declined to disclose any medical information “for reasons of participant confidentiality”.
“All trial investigators and participants will be updated with the relevant information and this will be disclosed on global clinical registries, according to the clinical trial and regulatory standards,” said AstraZeneca in a statement.
About 18,000 individuals have so far received the vaccine known as AZD1222 in the trial taking place in the UK, US, South Africa, and Brazil.
“In large trials such as this, it is expected that some participants will become unwell and every case must be carefully evaluated to ensure careful assessment of safety,” Oxford said in a statement.
The size and pace of development of the Covid-19 vaccine product pipeline is unprecedented, expanding to more than 200 candidates in less than a year since the discovery of the pathogen in humans in December last year.
As of September 9, results from eight investigational vaccines have been shared through either a peer-reviewed publication (six) or in the form of an advanced manuscript (two). Three vaccines are in Phase II, three in Phase I/II, and the remaining two are in Phase I, and the depth of the data shared ranges from complete to a preliminary analysis.
During Phase I, small groups of people receive the trial vaccine. In Phase II, the clinical study is expanded and vaccines are given to people who have characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In Phase III, the vaccine is given to thousands of people and tested for efficacy and safety.
Five out of eight vaccines that have moved into pivotal Phase III trials.
Apart from the Oxford vaccine, two other vaccines that are currently undergoing large testings in the US include one by Moderna Inc and the other by Pfizer and Germany’s BioNTech. About two-thirds of the needed participants have already been recruited for the studies. The two companies Saturday announced that they were going to enlarge the Phase III trial of their Covid-19 vaccine by 50 per cent, to allow them to collect more safety and efficacy data and to increase the diversity of the study’s participants.
In a press release, Pfizer and BioNTech said that they would increase the size of the study in their US Phase III from 30,000 to 44,000 participants.
“The companies continue to expect that a conclusive readout on efficacy is likely by the end of October,” the press release said.
The vaccine will lower enrolment age to 16 years and include patients with hepatitis C or hepatitis B. The companies also intend to test their vaccine in people living with HIV but are stable.
Meanwhile, Moderna, said that it is working to increase the diversity of trial participants in its study, “even if those efforts impact the speed of enrollment.” The company started its trial on the same day as Pfizer, said on September 4.
Both vaccines require a second shot; Pfizer/BioNTech’s is given after three weeks, while Moderna’s is given after four.
The Pfizer trial also starts to count cases of Covid-19 sooner after participants receive their shots than the Moderna study. It however is likely to be one of the most difficult of the experimental vaccines to distribute, should they prove effective as the vaccine must be kept at a temperature of -70 degrees Celsius.