CoronaVac, China’s live attenuated vaccine, demonstrates its immunogenic capabilities

China is also working hard to create a vaccine against the coronavirus from this spring. While Pfizer, Russia is Modern announced in the press the effectiveness of their foal, the candidate vaccine from the Chinese laboratory Sinovac, which already markets three vaccines againsthepatitis To the’Hepatitis B and the influence, also advances. The results of phases I and II of clinical tests of his CoronaVac have just been published in The Lancet Infectious Disease.

Obviously, Sinovac did not wait for the publication of these results to continue his journey. Phase III began last September, particularly in Turkey and Brazil. Furthermore, the trials had to be stopped following a serious unexpected event that occurred in October among the participants of the Butantan Institute in Brazil. On November 11, Brazilian health authorities announced authorized the resumption of tests.

The CoronaVac vaccine is based on the same principle as the first vaccines in history, live attenuated vaccines which consist of injecting a weakened version of SARS-CoV-2 to stimulate the immune system. Pasteur used this method to design his vaccine against anger. The BGC vaccine, which protects against bacterium from tuberculosis (the bacillus of Calmette and Guérin), it is also a live vaccine attenuated. These vaccines are highly immunogenic and provide long lasting protection. duration, so much so that they are sometimes not recommended in immunocompromised patients, such as those with Page. But this remains to be confirmed in the specific case of CoronaVac.

A randomized, double-blind clinical trial

The results published in The Lancet Infecitous Disease cover both phase I and phase II clinical trials. The tests are the same, except that phase II is performed on a larger number of people. Here, twenty for phase I in each group, against a hundred for phase II. This is a total of 743 people, aged between 18 and 59, who have never been infected with SARS-CoV-2. Scientists are therefore interested in seroconversion induced by vaccination, namely the appearance ofantibody specific for SARS-CoV-2 in these once naïve individuals.

Two vaccine doses were tested: 3 and 6 μg of virus weakened in 0,5 ml of hydroxidealuminum. A first group received a dose on day 0 and day 14 and a second group on day 0 and day 28. Each person is assigned to a random group (randomization) and neither doctors nor patients know the contents of the syringe ( double blind). Finally, the results obtained are compared with a group placebo.

At the end of this protocol of vaccination, the scientists studied for each group and for each dose the tolerance, or the occurrence of side effects following the injection, in addition to seroconversion.

A tolerated and immunogenic vaccine

Overall, vaccination was well tolerated. The most common side effects are ache 20 to 25% of participants, followed by discomfort around the injection site for 25-30% of participants, regardless of the dose injected.

Regarding the appearance of antibodies, the scientists followed two parameters: neutralizing antibodies and antibodies specific to RBD from protein S of SARS-CoV-2 14 and 28 days after the second dose. For the 100 people enrolled in phase 2, vaccination produced neutralizing antibodies in over 90% of them.

Performing one injection on D0, then a second one on D28 with the concentrated vaccine at 6 μg is the most effective formula for stimulating the production of antibodies: neutralizing antibodies and IgG anti-RBD group were observed in 100% of people.

These clinical trials were not concerned with the cellular immune response (activation of lymphocytes T), but this will be studied in phase III. In this phase, it is impossible to estimate the effectiveness of CoronaVac, it will be necessary to await the first conclusions of the third phase of clinical trials.

Covid-19: the vaccine tested on the monkey confirms the hopes of a preventive treatment for humans

Article published on May 22, 2020 by Futura with AFP-Relaxnews

Research on a vaccine tested on monkeys continues. New studies appear to confirm the first tests and are promising because they are the first to show that the monkey develops a immunity protective against Sars-CoV-2. They are also encouraging because they show that a vaccine would then be possible for humans.

Monkeys vaccinated or infected with the new coronavirus have developed antibodies that allow them to be protected against a new infection, according to two “promising” studies despite large differences between macaques and humans, published Wednesday in the journal. Science. ” Our results increase the optimism that it will be possible to develop vaccines against the COVID-19Dan H. Barouch, the researcher who conducted the two studies at the Beth Israel Deaconess Medical Center (BIDMC), in Boston.

” Further research will be needed to answer important questions about the duration of protection In addition to the specificities of the vaccines against Sars-CoV-2 developed for humans, explains, while the pandemic it has already claimed more than 325,000 lives worldwide since it emerged in China in December.

These studies ” among the first to prove it primates non-humans can develop immunity protective against SARS-CoV-2, are promising He greeted the scientific magazine Science.

Beware despite these encouraging results

In the first study, nine adult macaques were infected with a virus SARS-CoV-2. After recovery, they underwent a second infection 35 days later. Everything then proved that ” few or no symptoms “.

“These data indicate that a Sars-CoV-2 infection caused a immunity protective “in macaques, its authors conclude by emphasizing the” important differences In the coronavirus infection in macaques and humans. In the second study, the researchers gave vaccines experiments on 35 adult macaques.

When these monkeys were nasally infected with Sars-CoV-2 six weeks later, ” they presented the levels antibody in the blood enough to neutralize the virus within two weeks “, highlighted Science.

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The immune responses would also be very different

These levels were similar to those found when recovering humans after being infected with the novel coronavirus, the researchers said. ” These are very encouraging studies Responded Lawrence Young, a researcher at the University of Warwick who did not participate in the work.

But infections with the new coronavirus ” it would be different in humans, including the virus’s ability to infect many other tissues and cells in humans. The immune responses would also be very different », He warns.

Coronavirus: an effective vaccine tested on monkeys

Futura article with AFP-Relaxnews, published on 25 April 2020

A powerful Chinese laboratory is testing a vaccine in monkeys, claiming it is effective. These are, for some scientists, serious preclinical data, but the long-term efficacy of this vaccine remains to be questioned.

An experimental vaccine has, for the first time, ” widely protected “Monkeys against the new coronavirus, says a Chinese laboratory behind the research. The vaccine, which uses agents pathogens of the virus that causes Covid-19 disease, eight were given macaques rhesus, which were then artificially contaminated three weeks later, according to research published by pharmaceutical giant Sinovac Biotech.

No detectable traces of the virus

” Fourth macaques who received the high-dose vaccine had no detectable traces of the virus in the lungs seven days after their contamination », Assures the laboratory that published these results on April 19 on the site bioRxiv. Four more monkeys, to whom the vaccine was given at a lower dose, had an increase in theirs viral load in the body but still managed to resist the disease. These results still need to be peer-reviewed before validation by the scientific community.

Sinovac, a Nasdaq-listed company, has started clinical trials of the same vaccine in humans since April 16. Asked by AFP, the lab declined to comment on this topic. ” This is the first serious preclinical data I see on an experimental vaccine “, Commented on Twitter the virologist Florian Krammer, of the Icahn School of Medicine in New York. ” The question is whether this protection lasts long », Observes the immunologists Lucy Walker, de l ‘University college in London.

Two more experimental Chinese vaccines in progress

In addition to the Sinovac project, Beijing has approved two other experimental vaccines launched on the one hand by the Military School of Medical Sciences and the group of biotechnology CanSino, listed in Hong Kong, and on the other hand, by the Institute of Biology and the Institute of Virology in Wuhan, the city where the coronavirus first emerged late last year. The American Modern laboratory simultaneously announced in mid-March that it would also conduct clinical trials for an experimental vaccine with United States.

Pharmaceutical groups and research laboratories around the world have entered a race against time to develop treatments and vaccines against the COVID-19. L ‘epidemic it killed more than 190,000 people with nearly 2.7 million infected, using a variety of new technologies. The estimated time for a vaccine is 12-18 months minimum.