AstraZeneca may conduct fresh trials for the Oxford COVID-19 vaccine after it was revealed that the dose regimen that showed 90% efficacy was not a part of the original approved trial protocol. After sharing that the vaccine candidate is showing 62-90% efficacy by two different dosages, several academicians and scientists raised questions about why the two different dosages were not shared with public.
The pharmaceutical also shared an average result of 70% efficacy which raised several red flags as the trials were of different dosages as well as were conducted in different areas. While in the UK trial over 2,741 assessed participants received a half shot of (~2.5 x1010 viral particles) followed by a full dose (~5x1010 viral particles), the 8,895 participants assessed in Brazil received two full doses of the vaccine. A Reuters report later revealed that this trial in the UK was different due to a dosage error.
The company wants the new test to confirm the 90% efficacy rate that the shot showed in a portion of an existing trial, Chief Executive Officer Pascal Soriot said. "Now that we've found what looks like a better efficacy we have to validate this, so we need to do an additional study," Soriot said in his first interview since the data were released. It will probably be another "international study, but this one could be faster because we know the efficacy is high so we need a smaller number of patients."
According to Soriot, this will not affect the existing regulatory approvals for the vaccine in UK and the European Union. As the US Food And Drug Authorization does not approve vaccines on results from elsewhere, the approval in US will only be after the results from the US trials will be shared. UK on November 27 announced that it has asked its medicine regulator to assess if the vaccine can be given temporary authorization,
However, several scientists took to Twitter to express their displeasure with AstraZeneca not being transparent through the process. Natalie Dean, professor of biostatistics at University of Florida was one of the first ones to raise all the red flags in relation to the transparency of the study. She raised questions on how different protocols were being followed in different countries and even questioned whether combining two sets of results to reach an average efficacy followed scientific norms.
When Sarah Gilbert, the professor who assisted the Jenner Institute to create the AZD1222 vaccine heard about the questions being raised on the dosage of the vaccine, she decided to take it in a positive stride instead. "As academicians, we always want to keep learning. We will try to understand why these discrepancies in these dosages arose in the efficacy." The new clinical trials are being conducted to validate this finding.
It is still unclear as to why a lower dosage showed a higher efficacy. Indian scientist Dr. Gagandeep Kang who is consulting the Indian government for vaccine development explained that the plausible cause could be that the lower dosage is not immune to the vector while the higher dosage may act against the chimpanzee adenoviral vector itself.
Even Dr. Soumya Swaminathan, World Health Organization's Chief Scientist cautioned in a Tuesday interview with Bloomberg Television that more complete data is needed to understand potential discrepancies between the doses. "We really need to wait for larger numbers, longer follow-up, to see whether these differences actually continue in the future," she said.
As for India, its hopes are on the Oxford vaccine as it has not revealed any plans to sign the dotted line for procuring the Moderna and Pfizer vaccines which are more effective and transparent. The cold storage requirements for both the vaccine may prove to be an hindrance for India as they do not match its existing capacity.
Adar Poonawalla, CEO of Serum Institute which is producing the vaccines for India and is following the two full doses regimen said in a statement that the vaccine works with a 60-70% efficacy. The World Health Organisation as well as the Indian Ministry of Health and Family Welfare had set a benchmark of a COVID-19 vaccine candidate having at least 50% efficacy would be sustainable for use.