Promising results for the two vaccines tested

Photo: John Cairns University of Oxford via Associated Press
Adrian Hill, director of the Institute Jenner, directs research to find a vaccine against the COVID-19 at the University of Oxford.

The world is moving closer to a vaccine against the COVID-19 ? Two applicants, one chinese and the other british, have offered encouraging results after being tested on patients. But in both cases, the crucial phase of clinical trials remains to be done before considering a large-scale marketing.

These results, very expected within the scientific community, were published in rapid succession in the prestigious scientific journal The Lanceton Monday.

The vaccine developed in the United Kingdom is the fruit of a partnership between the University of Oxford and the pharmaceutical AstraZeneca. At the end of a clinical study conducted on more than 1000 patients, it has resulted in two immune responses distinct antibodies, but also t lymphocytes. these are white blood cells that fight organizations aggressors — such as SARS-CoV-2 — and remember their features in the case of a new infection.

This dual immune response has also been observed in the vast majority of patients who received the vaccine in chinese, which is currently being developed in Wuhan and funded by the biotechnology giant CanSino. About 500 people have participated in the clinical trial.

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The two vaccines are based on an adenovirus, chimpanzee in the case of Oxford and human CanSino. This family of viruses, a very common cause of respiratory diseases such as seasonal influenza. However, they have been genetically modified to produce the viral protein of the novel coronavirus, and avoid a replication in the body.

Nearly a month after the injection (28 days), more than 90% of the participants of the trial british had neutralizing antibodies in the blood, and about 85 % in the essay chinese. Other good news : no serious side effects have been reported after the tests. The effects of the vaccination are mainly limited to headache, fever, fatigue, or pain at the injection site.

“This is a positive outcome, but there is still a long way to go,” commented the director of emergencies at the health of the world health Organization, Michael Ryan. It is ” a step in the right direction “, but ” further testing is still needed “, for its part, has responded to the british prime minister, Boris Johnson.

Alain Lamarre, a professor in immunology and virology at the national Institute of scientific research (INRS), is of the same opinion. The two vaccines, non-hazardous, have triggered “an immune response similar to the one developed naturally in infected people,” he said in an interview. But clinical trials remain preliminary.

This is a positive outcome, but there is still a long way to go

— Michael Ryan

“There is talk of a few hundred people tested. It is relatively small to extrapolate to the general population “, explains the specialist. Not to mention that the patients involved are ” volunteers age adult in good health “.

The ultimate phase

Only the test of chinese as a group of patients with more than 55 years. The latter, moreover, had lower rates of antibodies. “It is possible that an additional dose [of the vaccine] is necessary to cause a stronger immune response in the elderly population “, has been judged one of the authors of the study, Wei Chen, Institute of biotechnology, Beijing.

To clarify this grey area, among others, two vaccines candidates have yet to cross the third and ultimate phase of their development, resumes Alain Lamarre, INRS.

During this stage, ” crucial “, it evaluates the effectiveness of the vaccine to protect against infectious disease by administering it to thousands of people. Of the elderly or of children, for example, or the citizens who suffer from chronic diseases, therefore more at risk of complications.

Also, this phase takes place in the context of the “natural” of the disease, require persons infected in a real life context. “It is a little at the mercy of chance and of the evolution of the pandemic at the local level,” says Mr. Lamarre.

Can we still hope for a vaccine by the end of the year ? With a caution about the scientist, the professor believes the timeline plausible, but leans rather to the beginning of 2021. “But that may change quickly “, lance-t-il. It is not uncommon for vaccine projects fail at the third phase, due to lack of patients.

In other words, the race between researchers and laboratories around the world — including Canada — is not nearly complete. Nearly 200 projects of vaccines are on the ranks, and 23 are currently being tested on humans.

With Agence France-Presse