Updated: November 24, 2020 7:37:08 am
The AstraZeneca-Oxford vaccine is called AZ1222; its Indian version, Covishield, is currently in late-stage testing. (Reuters photo)
The Swedish-British company AstraZeneca and the University of Oxford information published on Monday on the effectiveness of his vaccine, AZD1222. In India, a version of this vaccine (Covishield) is being tested:
What are the findings?
The efficacy of AZD1222 (its ability to reduce the onset of symptoms in vaccinated individuals) varies depending on the combination of doses administered during ongoing trials in the UK and Brazil. Based on interim analysis, AZD1222 was found to reduce the number of symptomatic Covid-19 cases by 90% in those who received a combination of a half dose of the vaccine followed by a full dose one month apart. But the efficacy appeared to drop to 62% when the vaccine was given in two full doses at least a month apart.
It is significant that a combination of a lower dose and a higher dose was found to actually produce greater efficacy. This means that more people can be effectively vaccinated using the same limited supply, which could make the candidate attractive to governments targeting a larger population.
What explains the lower efficacy with two full doses?
This is still unclear. While experts speculate on the possible reasons, they wait for more data to issue an informed opinion.
“I would say that it is possible that an exposure to a lower dose initially primes the system much better, and that the second dose raises the body’s immune response to a much higher level, but this is speculative,” said Dr. K Srinath Reddy, President of Public Health Foundation of India. “It is likely that if the first dose itself is so high that it depletes the body’s immune response, the next dose will not elicit the nature of the intensified response required. It can be like shifting gears too fast when driving a car – it can warm up the engine, but it doesn’t necessarily mean speed. That is a possibility here, but it must be explored.
What does this mean for Covishield?
Covishield, developed by the Serum Institute of India (SII) using the “master seed” from AZD1222, is undergoing late-stage human trials in India with 1,600 participants. The trial aims to study the safety and immunogenicity (ability to elicit an immune response) of Covishield compared to the vaccine developed by Oxford and AstraZeneca.
According to experts, this is a bridge study that can help SII launch Covishield in India by using additional information from global AZD1222 trials to support its applications to India’s drug regulator. If the study shows that the two candidates are similar, the efficacy results for IBS may also be similar.
There is one caveat: it is unclear if the Covishield trials have been testing participants with different dosing regimens the way the AZD1222 trials are being conducted.
“If they are using only the full dose regimen, Covishield is likely to get a similar efficacy reading of around 60%. This would still be enough for them (SII) to apply for approvals from the Indian drug regulator, because their guidelines suggest that a vaccine must meet an efficacy of around 30-50% for a Covid-19 vaccine to receive approval. “He said. Massachusetts-based vaccine expert Dr. Davinder Gill.” Right now, a lower efficacy of 60-70% may not be a big problem, because India doesn’t have a Covid-19 vaccine yet. But, a year from now, when several vaccines have been approved, then a 15-20% difference in efficacy will matter, ”he said.
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How does this vaccine compare to other candidates in terms of efficacy and cost?
Other vaccines that have announced efficacy information include those for Pfizer-BioNTech, Modern with the U.S. National Institute of Allergy and Infectious Diseases (NIAID) and Gamaleya Research Institute of Epidemiology and Microbiology of Russia. None of the announcements, including the one for AstraZeneca, has been published in a scientific journal and peer reviewed, which means that no further information about their data has been seen yet.
Pfizer says its BioNTech vaccine, which it uses mRNA technology, has an effectiveness rate of about 95%. However, the candidate requires near-cryogenic levels of cold storage, making large-scale delivery a challenge in countries like India. Its price, yet to be announced, is estimated at more than $ 19 (more than Rs 1,400) per dose.
The Moderna and NIAID vaccine, which also uses mRNA technology, is around 94.5% effective. While it requires freezers of around –20 ° C, it can also be stored in refrigerated temperatures of around 2 ° C to 8 ° C for up to a month. This vaccine is expensive, around $ 25 to $ 37 per dose for different governments, making it prohibitive for countries like India, according to experts.
The Russian Sputnik V vaccine uses technology similar to AZD1222 and Covishield, a viral vector that does not replicate. The Russian Direct Investment Fund (RDIF) said it was around 92% efficient. This vaccine is stored at -18 ° C in its liquid form and around 2 ° C to 8 ° C in its lyophilized form, which could facilitate its transport across large geographies. RDIF has said its cost will be “much lower” than the Pfizer and Moderna vaccines.
In India, SII CEO Adar Poonawalla has said that Covishield, which can also be stored at temperatures between 2 ° C and 8 ° C, will be priced at around $ 3 per dose to the government and almost $ 7-8 for the “general public”. . 📣 Express Explained is now on Telegram
What questions remain unanswered?
Experts say the biggest question about any Covid-19 vaccine is the uncertainty around how long immune response it generates will last.
“We do not yet know the duration of the protection. We have reasonable information on efficacy, but it is not complete and is not discussed by regulators. We also have partial information on safety, because some of the delayed effects of the vaccine are still unknown, ”said Dr. Srinath Reddy.
How soon can India get this vaccine? Will everyone understand?
While IBS has already started to store doses of Covishield, announced this month that it had already manufactured around 40 million doses for India; The company has also clarified that the vaccine will be limited to priority groups such as frontline workers and the elderly to begin with. It would likely be available to the general population in April, according to Poonawalla.
Last week, he said the firm would apply to the Comptroller General of Drugs in India for emergency use authorization, probably in December, if AZD1222 receives such approval in the UK and Europe after positive results.
While their goal is to increase monthly production from 50-60 million doses to 100 million by February, experts like Dr. Reddy caution that access will also depend on things like whether there are enough trained staff to administer the vaccine to a larger population. big.
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