The University of Oxford and the AstraZeneca laboratory announced, on Monday (26), that the vaccine they are developing against Covid-19 induced “a strong immune response” in the elderly during phase 2 tests in the UK. Preliminary test results will be published “in the coming weeks” in a scientific journal, according to Oxford.
The Oxford vaccine is one of four that undergo phase 3 testing in Brazil – the last step before it can be released for general use.
Oxford vaccine induced strong immune response in elderly volunteers in phase two
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In the UK, it was tested on people aged 56 to 69 and in a second group, with elderly people aged 70 and over. Preliminary test results were discussed by researcher Andrew Pollard, one of the study’s coordinators at the university, at a conference.
In July, the university had already reported results on younger volunteers, aged 18 to 55 years old.
Phase 2 of testing a vaccine verifies its safety and ability to generate a defense system response. It is usually done with hundreds of volunteers. Phase 1 is performed on dozens of people, and phase 3 on thousands (see details further down in this report).
AstraZeneca said the result was “encouraging”.
“It is encouraging to see that immunogenicity responses were similar between older and younger adults and that to reatogenicity [geração de efeitos adversos] was lower in older adults, in which Covid-19 is more serious, “said a laboratory spokesman.
Oxford researcher analyzes the vaccine developed for the coronavirus on June 25 – Photo: John Cairns, University of Oxford via AP
Vaccines in tests against Covid-19 have sought to stimulate two responses of the defense system: one is the generation of antibodies that neutralize the new coronavirus (Sars-CoV-2), and the other is the response of the cellular immune system, which involves T cells.
The immune response was seen “in both parts of the immune system“, according to Oxford.
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According to Oxford, trials that are still going on will provide more data about the vaccine, but the initial result “represents an important milestone and assures us that the vaccine is safe for use and induces strong immune responses in both parts of the immune system. in all groups of adults “.
Last week, a Brazilian volunteer who participated in the vaccine tests died of Covid-19. The volunteer, however, did not receive the vaccine being tested, but a placebo (an inactive substance).
In tests randomized (random), as are the ones for the Oxford immunization, part of the volunteers receives the vaccine and the other part, a placebo. Determining who will receive what is done at random (as the name says). Usually, both groups have the same number of participants (or very close numbers).
In addition to being randomized, the tests are also done with “double-blind” – in which neither the researchers nor the volunteers know who received the vaccine or not.
The group that no gets immunization is called “group control“, and serves to allow scientists to compare the results seen in the other volunteers, who actually got the vaccine.
How the 3 phases work
In testing a vaccine – usually divided into phases 1, 2, and 3 – scientists try to identify serious adverse effects and whether the immunization was able to induce an immune response, that is, a response of the body’s defense system.
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Phase 1 tests usually involve dozens of volunteers; those in phase 2, hundreds; and phase 3, thousands. These phases are usually conducted separately, but because of the urgency to find a Covid-19 immunization, several companies have performed more than one step at the same time.
Before testing on humans, vaccines are tested on animals – usually on mice and then on monkeys.