Scientists at Oxford University say their experimental coronavirus vaccine has provoked a protective immune response in hundreds of people who got the shot in the early trial.
Crucially, nobody has had any bad side effects from the vaccine and it stimulated the immune system as scientists hoped it would. Some people developed headaches, tiredness and pain in their arm after they were given the jab, but none of the side effects were severe, scientists said.
British researchers first began testing the vaccine in April in about 1,000 people, half of whom got the experimental vaccine. Such early trials are usually designed only to evaluate safety, but in this case experts were also looking to see what kind of immune response was provoked.
In research published on Monday in the journal Lancet, scientists said that they found their experimental vaccine produced a dual immune response in people aged 18 to 55.
“We saw a good immune response in almost everybody,” said Dr Adrian Hill, director of the Jenner Institute at Oxford University.
“What this vaccine does particularly well is trigger both arms of the immune system,” he said.
Hill explained that due to the vaccine neutralizing antibodies are produced — molecules which are key to blocking infection. In addition, the vaccine also causes a reaction in the body's T-cells which help to fight off the coronavirus.
He said that larger trials evaluating the vaccine's effectiveness, involving about 10,000 people in the UK as well as participants in South Africa and Brazil are still underway. Another big trial is slated to start in the US soon, covering about 30,000 people.
How quickly scientists are able to determine the vaccine's effectiveness will depend largely on how much more transmission there is, but Hill estimated they might have sufficient data by the end of the year to decide if the vaccine should be adopted for mass campaigns.
He said the vaccine seemed to produce a comparable level of antibodies to those produced by people who recovered from a COVID-19 infection and hoped that the T-cell response would provide extra protection.
“There is increasing evidence that having a T-cell response as well as antibodies could be very important in controlling COVID-19,” Hill said. He suggested the immune response might be boosted after a second dose; their trial tested two doses administered about four weeks apart.
Hill said Oxford's vaccine is designed to reduce disease and transmission. It uses a harmless virus — a chimpanzee cold virus, engineered so it can't spread — to carry the coronavirus' spike protein into the body, which should trigger an immune system response.
Hill said Oxford has partnered with drug maker AstraZeneca to produce their vaccine globally, and that the company has already committed to making 2 billion doses.
“Even 2 billion doses may not be enough,” he said, underlining the importance of having multiple shots to combat the coronavirus.
“There was a hope that if we had a vaccine quickly enough, we could put out the pandemic,” Hill said, noting the continuing surge of infections globally. “I think it is going to be very difficult to control this pandemic without a vaccine.”
Numerous countries, including Germany, France, the Netherlands, Italy, US and the UK have all signed deals to receive hundreds of millions of doses of the vaccine — which has not yet been licensed — with the first deliveries scheduled for the fall. British politicians have promised that if the shot proves effective, Britons will be the first to get it.
About a dozen different experimental vaccines are in early stages of human testing or poised to start, mostly in China, the U.S. and Europe, with dozens more in earlier stages of development.
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