two vaccine projects produce “immune response”

The race for the Covid-19 vaccine is progressing, with the results of clinical trials still preliminary but encouraging on two projects – one British, the other Chinese. Published Monday July 20 in the British medical journal The Lancet, these vaccine projects generate “A strong immune response” and are well tolerated by patients.

  • The first, developed by the University of Oxford in partnership with the pharmaceutical group AstraZeneca, has generated the production of antibodies and T lymphocytes, two types of immune responses, in a clinical trial on more than 1,000 patients.
  • The second project, carried out in Wuhan (China) by researchers from several organizations, including the Military School of Medical Sciences, and funded by the Hong Kong-listed biotechnology group CanSino Biologics, also led to this dual immune response against the coronavirus in most participants, according to a separate trial involving approximately 500 people.
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These clinical trials are still in a preliminary phase (phase 1/2 and phase 2), which tests the tolerance and the appearance of an immune response after the injection of the vaccine, compared to a placebo. Their effectiveness will still have to be established in a phase 3 trial, on a larger number of participants, before considering their large-scale commercialization.

“It is not yet known whether these levels of immunity can protect against infection. (…) nor if this vaccine can protect the most fragile of the serious forms of Covid-19 “commented Jonathan Ball, professor of molecular virology at the University of Nottingham (UK), who was not involved in the study.

Race against time

However, these results were eagerly awaited: many researchers and laboratories around the world are racing against the clock to find a safe and effective vaccine against Covid-19. Nearly 200 candidate vaccines are being developed, including 23 in the clinical phase (i.e. tested in humans).

Prime Minister Boris Johnson hailed on Twitter “An important step in the right direction”, while stressing that“Other tests [étaient] still needed “.

“This is a positive result, but there is still a long way to go”said Michael Ryan, director of health emergencies at the World Health Organization (WHO), while its director general, Tedros Adhanom Ghebreyesus, called for “Do more with the tools at our disposal”while waiting for a vaccine search to bear fruit.

“If our vaccine works, this is a promising option, because this type of vaccine can be easily produced on a large scale”said Sarah Gilbert, a researcher at the University of Oxford.

Both the Oxford vaccine and CanSino’s vaccine are based on an adenovirus (the first chimpanzee, the second human), a family of very common viruses that cause colds in particular. They have been genetically engineered to produce the SARS-CoV-2 spike protein, the idea being that the patient’s immune system can later “recognize” him if he is actually infected. The modified virus does not replicate in the body, which makes it safer, especially for fragile patients.

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No serious side effect

Neither trial had any serious side effects. Headache, fever, fatigue and pain at the injection site were the most common side effects observed. Twenty-eight days after the injection of the candidate vaccine, more than 90% of participants in the UK trial had neutralizing antibodies in their blood, about 85% in the Chinese trial.

Only the Chinese trial included patients over 55 years of age; in the latter, the antibody levels observed were lower. “It is possible that an additional dose [de vaccin] is necessary to induce a stronger immune response in the elderly population “, said one of the authors, Wei Chen, of the Beijing Biotechnology Institute.

The two vaccine projects also resulted in 100% and more than 90% of participants, respectively, in the production of T lymphocytes, white blood cells whose role is to eliminate organisms identified as dangerous and to remember the characteristics of the disease. aggressor in the event of a new infection.

Among other vaccine projects at an advanced stage, the American biotech Moderna announced last week that it would begin phase 3 of its candidate vaccine against Covid-19 on July 27, to test its effectiveness on 30,000 people in the United States: half of them will receive a dose of 100 micrograms, the others a placebo.

Only the Chinese laboratory Sinovac is as advanced: it announced on July 6 that the third and last phase of development of its vaccine would begin ” this month “, in collaboration with the Brazilian Butantan. She “Will include around 9,000 health professionals” in this country hit hard by the Covid-19 epidemic.

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The World with AFP