what we know about the two most promising vaccine projects


Two vaccines tested on humans produced an encouraging immune response against Covid-19, according to the results of two clinical trials published Monday in the British medical journal “The Lancet”.

One is British, the other Chinese. Two vaccine projects against the new coronavirus with conclusive results were published on Monday July 20 by the British medical journal The Lancet. They produced an immune response in the patients tested, without any serious side effects.

Their effectiveness against Covid-19 has yet to be established before considering large-scale commercialization. Franceinfo summarizes what we know about these two projects.

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One is English, the other Chinese

The first vaccine candidate, AZD1222, was developed in the UK by the University of Oxford and the pharmaceutical group AstraZeneca. It was created from a common cold virus affecting chimpanzees, which looks rather like the Covid-19 so that the human immune system can attack it. It has been tested on 1,077 volunteers, aged 18 to 55.

The Chinese company CanSino Biologics has developed the second vaccine candidate, Ad5-nCOV, from a human cold virus. It was tested in Wuhan on 508 volunteers ranging from 18 to 83 years old, 126 of whom were given a placebo.

They generate “a strong immune response”

This is a notable advance among the dozens of Covid-19 vaccines that are being developed. People who have been vaccinated make antibodies against Covid-19.

For the vaccine candidate, out of the 543 people who received the vaccine (the other participants received a vaccine against meningitis), 90% of the participants developed antibodies. For the Chinese project, they are 85%.

Besides the immune response, it should be noted that the side effects are mild and similar to those of other vaccines: headache, fever or fatigue.

Large-scale clinical trials still need to be done

These conclusive results have so far only been observed on a few hundred people. With phase 3 of clinical trials, large-scale testing is expected to begin.

“The question now is whether these antibodies make it possible to prevent infection, or in all cases to control infection, or to prevent severe forms”, explained Tuesday, July 21 on franceinfo Odile Launay, infectious disease specialist at Cochin hospital in Paris.

“It is not yet known whether the vaccine is working, and how long it will stay so”, estimates on franceinfo Eric Caumes, head of the infectious and tropical diseases department at the Parisian hospital of Pitié-Salpêtrière: Just because there are antibodies does not mean the body is protected against the virus. We must also check if it works for everyone: the elderly can sometimes react less well to vaccines “.

Not a single vaccine

The researchers will also have to carry out studies on populations which, according to their age or their geographical origin, do not present the same degree of immunity before the injection of the vaccine. “In India, 80% of adults have antibodies against this vector, compared to 60% in South Africa and less than 30% in the United States”, say the authors of the study by Wuhan researchers.

It would then be a variable dose vaccine, depending on the patient profiles: “We are working to identify the most promising vaccines according to the different categories. There will probably not be a single vaccine for everyone”, Assures the researcher Kate Bingham to the BBC (link in English).

For the third phase of the AstraZeneca clinical study, 10,000 Britons will take part in the third phase (repeat) of the test, along with 30,000 people in the United States, 2,000 in South Africa and 5,000 in Brazil.

Generalized vaccination a priori not for tomorrow … but the vaccines are ordered

Countries do not want to be left behind once the vaccine hits the market. On June 12, the German, French, Dutch and Italian health ministers signed a contract with the AstraZeneca laboratory to secure vaccines for pre-order: “The agreement in principle reached with the AstraZeneca laboratory provides that the latter, if its project is successful, will provide up to 400 million doses of vaccine at cost price”, explains the French government in a press release.

According to the BBC (link in English) the British have already ordered 190 million doses of different vaccines, including 100 of the product offered by the University of Oxford. “This type of vaccine can be easily produced on a large scale”, commented Sarah Gilbert, a researcher at Oxford University who developed the vaccine.

Other vaccine projects are under study

More than a hundred vaccines are under study worldwide, according to the New York Times, including 26 in clinical trials.

On Wednesday July 22, another Chinese vaccine, this time from the Sinovac Biotech laboratory, entered phase 3. These tests are carried out in Brazil, the second country in the world most affected by the pandemic, where 9,000 volunteers will receive injections over three months. Called Coronavac, this vaccine could be produced at 120 million doses by early 2021, if its effects are conclusive.

While awaiting the results of the final stages of the vaccines, “do not get carried away “, advocates Eric Caumes. “We have already had enough of the rush in this epidemic. Instead, let’s do with what we have – masks, hydroalcoholic gel and social distancing “, he concludes, “rather than with what we don’t have yet “.

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