A The Covid-19 vaccine developed by the University of Oxford and the pharmaceutical giant AstraZeneca sparked an immune response in a study of approximately 1,000 patients, according to provisional results published Monday.
The data, published in the medical journal The Lancet, also shows that the vaccine caused side effects, such as fever, headaches, muscle aches, and injection site reactions, in about 60% of patients. All side effects were considered mild or moderate, and all resolved within the course of the study.
While the Oxford-AstraZeneca vaccine, known as AZD1222, has moved more quickly to large-scale studies of any major contender, and AstraZeneca has said billions of doses could be made, the new data represents the first insight that Researchers have achieved its effectiveness. . They show a relatively safe vaccine, although the side effects were greater than for a meningitis vaccine, with which it was compared, which involves the immune system to fight the virus.
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The Lancet also released the results of another vaccine, from Chinese biotech CanSino, which had been previously released. The Phase 2 results showed that, as seen in the Phase 1 data, the vaccine induced neutralizing antibody responses, which could be vital in preventing dangerous symptoms of the disease, in most subjects. But additional studies continue to show that this vaccine works better in some people than others. And among those that didn’t work as well were people 55 and older, a key target for the Covid-19 vaccine.
“The results of both studies bode well for phase 3 trials, where vaccines must be tested in much larger populations of participants to assess their efficacy and safety,” wrote two vaccine researchers at Johns Hopkins University, Naor Bar. -Zeev and William Moss, in an accompanying editorial.
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Data on the Oxford-AstraZeneca vaccine do not provide enough information to predict whether it will be more effective than other vaccines that are also entering clinical trials.
AZD1222 is one of 23 possible Covid-19 vaccines They are being tested in clinical trials, according to the World Health Organization. Studies in which thousands of volunteers receive a vaccine or a placebo are necessary to know for sure whether any vaccine prevents SARS-Cov-2 infection and how well that vaccine works. Such studies have not been completed.
All the volunteers who received the vaccine developed neutralizing antibodies against Covid-19. However, participants who received a single injection of the vaccine did not produce significantly more antibodies than those who had recovered from Covid-19.
The vaccine also produced a response in T cells, a type of white blood cell that attacks virus-infected cells, according to the document. In a statement, Andrew Pollard of Oxford University, the study’s lead author, said the vaccine is intended to induce both types of responses. “We hope this means that the immune system will remember the virus, so that our vaccine will protect people for a long time, “he said.
In the Oxford trial, participants were between the ages of 18-55 and roughly divided between 50-50 between men and women. Ninety-one percent of the volunteers were white, while approximately 5% were Asian and less than 1% were black.
The vaccine has already entered large-scale tests, known as phase 3 trials, aimed at demonstrating its efficacy. It will also be part of the major tests taking place in the United States as part of the government-run program known as Operation Warp Speed.
Two other potential vaccines, which use a technology called messenger RNA that harnesses the body’s genetic message system to provoke an immune response, released preliminary results earlier this month. The vaccines, developed by Moderna, a Massachusetts biotech firm, and the team at German firm BioNTech and the pharmaceutical giant Pfizer, increased neutralizing antibody levels in patients. Both also caused side effects, including fevers, in many patients. Both are set to begin late-stage efficacy studies later this month. In a document also released Monday, BioNTech and Pfizer said their vaccine also induced T-cell responses.
AZD1222, which was developed by researchers at the Jenner Institute in Oxford, works differently, using a genetically modified virus called adenovirus, which was taken from chimpanzees and modified so as not to replicate and make people sick. It carries a gene for one of the proteins in SARS-Cov-2 and inserts it into the recipient’s cells. The virus causes the patient’s cells to produce that protein, which the immune system then recognizes as foreign. This results in an immune response.
The platform has not been used in an approved vaccine. But it has been used in experimental vaccines against viruses that cause other outbreaks, including the Ebola virus and the virus that causes Middle East respiratory syndrome (MERS). That work left the Oxford group ready when SARS-CoV-2, a related virus, became a threat.
In a statement, Sarah Gilbert, a professor at Oxford University who has been a key figure in the development of the platform, known as ChAdOx1, said the data, while early, looked promising.
“If our vaccine is effective, it is a promising option since this type of vaccine can be manufactured on a large scale,” said Gilbert.
Researchers from the National Institutes of Health. discovered that the AstraZeneca / Oxford vaccine protected monkeys against SARS-CoV-2, although protection did not completely prevent detection of the virus living in the airways of animals. Those results led to the start of the clinical trial on April 23 in people to be published on Monday.
AstraZeneca and Oxford announced their partnership on the vaccine on April 30. A study of 10,000 patients testing the vaccine is being run in the UK, and a separate test of 5,000 patients started in Brazil in June.
CanSino, meanwhile, is now planning a Phase 3 trial. Its Vaccine is what is known as a viral vector vaccine; it uses a live but weakened human cold virus, adenovirus 5, known as Ad5 for short, as a delivery system that teaches the immune system to recognize the SARS-CoV-2 coronavirus.
Many people have had previous adenovirus 5 infections, raising concerns that the immune system focuses on the Ad5 parts of the vaccine rather than the SARS-Cov-2 material fused to it. Many research groups working on viral vector vaccines stopped using Ad5 due to concerns about pre-existing immunity, which may reach 70% or more in some populations.
Data released Monday showed that subjects in the Phase 2 trial who did not have pre-existing low-level or Ad5 immunity developed neutralizing antibodies against SARS-CoV-2 at about twice the rate of people who had pre-existing immunity from high level. High-level pre-existing immunity was more common in people in the study age 55 and older. The researchers said the vaccine response in older adults will be studied in a phase 2b trial.
They suggested that the damping of the immune response due to pre-existing immunity to the Ad5 vector could be overridden by using a booster dose sometime three to six months after the original dose, a potentially uncomfortable dosing regimen that would not provide quick protection in people who are at the highest risk for Covid-19, older adults.
