British researchers began testing the vaccine in April on about 1,000 people, half of whom received the experimental vaccine. Such initial trials are generally designed only to assess safety, but in this case, experts were also looking to see what type of immune response was triggered.
In research published Monday in the Lancet journal, scientists said they found that their experimental COVID-19 vaccine produced a dual immune response in people ages 18 to 55.
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“We are seeing a good immune response in almost everyone,” said Dr. Adrian Hill, director of the Jenner Institute at the University of Oxford. “What this vaccine does particularly well is to trigger both arms of the immune system,” she said.
Hill said neutralizing antibodies are produced, molecules that are key to blocking the infection. In addition, the vaccine also causes a reaction in the body’s T cells that help fight the coronavirus.
He said that larger trials evaluating the vaccine’s effectiveness are still underway, involving about 10,000 people in the UK, as well as participants in South Africa and Brazil. Another major test is slated to begin soon in the United States, with the goal of enrolling some 30,000 people.
How quickly scientists can determine the vaccine’s effectiveness will largely depend on how much transmission there is, but Hill estimated they might have enough data by the end of the year to decide whether the vaccine should be adopted for mass vaccination campaigns.
He said the vaccine appeared to produce a comparable level of antibody to that produced by people who recovered from a COVID-19 infection and hoped that the T cell response would provide additional protection.
“There is increasing evidence that having a T cell and antibody response could be very important in controlling COVID-19,” Hill said. She suggested that the immune response could increase after a second dose; His trial tested two doses administered approximately four weeks apart.
Hill said the Oxford vaccine is designed to reduce disease and transmission. It uses a harmless virus, a chimpanzee cold virus, designed to keep it from spreading, to transport the coronavirus spike protein to the body, which should trigger a response from the immune system.
Hill said that Oxford has partnered with drug maker AstraZeneca to produce its vaccine worldwide, and that the company has already committed to producing 2 billion doses.
“Even 2 billion doses may not be enough,” he said, stressing the importance of having multiple injections to fight the coronavirus.
“There was hope that if we had a vaccine fast enough, we could turn off the pandemic,” Hill said, noting the continued increase in infections worldwide. “I think it will be very difficult to control this pandemic without a vaccine.”
Numerous countries, including Germany, France, the Netherlands, Italy, the United States and the United Kingdom, have signed agreements to receive hundreds of millions of doses of the vaccine, which has not yet been authorized, with the first deliveries scheduled for fall. British politicians have promised that if the shot turns out to be effective, the British will be the first to get it.
Last week, US researchers announced that the first COVID-19 vaccine tested there strengthened people’s immune systems just as scientists had hoped, and the injections will now enter the final phase of testing. That vaccine, developed by the National Institutes of Health and Moderna, produced the key molecules to block the infection in volunteers who contracted it, at levels comparable to those who survived a COVID-19 infection.
About a dozen different experimental vaccines are in the early stages of human testing or are about to start, primarily in China, the US, and Europe, with dozens more in the early stages of development.
British officials said on Monday they had also signed an agreement to buy 90 million doses of experimental COVID-19 vaccines developed by pharmaceutical giant Pfizer and others.
In a statement, the British government said it had secured access to a candidate vaccine developed by Pfizer and BioNTech, in addition to another experimental vaccine investigated by Valneva.
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