British drugmaker AstraZeneca on November 23 said its COVID-19 vaccine candidate being developed by the University of Oxford has shown an average efficacy of 70 percent.
The potential vaccine against the novel coronavirus maybe around 90 percent effective, the company said citing interim analysis of results from late-stage clinical trials.
"No serious safety events related to the vaccine have been confirmed," AstraZeneca said in a statement.
"This vaccine's efficacy and safety confirm that it will be highly effective against COVID-19 and will have an immediate impact on this public health emergency," Pascal Soriot, AstraZeneca's chief executive, said.
"Phase 3 interim analysis including 131 COVID-19 cases indicates that the vaccine is 70.4 percent effective when combining data from two dosing regimens," Oxford University said in a statement.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Oxford University also said there were no hospitalised or severe cases in anyone who received the vaccine.
One dosing regimen showed 62 percent efficacy when administered as two full doses at least one month apart, AstraZeneca said. Another dosing regimen was 90 percent effective in preventing COVID-19 when given as as a half dose followed by a full dose at least one month apart.
The announcement comes shortly Pfizer-BioNTech and Moderna said their experimental vaccines against COVID-19 had shown around 95 percent efficacy.
In India, Serum Institute of India (SII) is conducting clinical trials of the Oxford-AstraZeneca vaccine against the virus.
SII CEO Adar Poonawalla in a tweet said more information on the vaccine will be provided soon.
"I am delighted to hear that, Covishield, a low-cost, logistically manageable and soon to be widely available, COVID19 vaccine, will offer protection up to 90 percent in one type of dosage regime and 62 percent in the other dosage regime. Further details on this, will be provided this evening," Poonawala said.
AstraZeneca added that it will seek an Emergency Use Listing from the World Health Organisation (WHO).US drugmaker Pfizer and its German partner BioNTech have applied to the the Food and Drug Administration (FDA) for emergency use authorisation.