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Vaccines against Covid-19: gray areas around serums produced in China

2021-04-13T08:29:04.350Z

The serums developed in China would ultimately not be very effective, as officially recognized by a senior official in the country. A



They are probably not about to arrive in Europe.

In any case, the vaccines against Covid-19 developed in China "do not have a very high rate of protection".

It was the director of the Chinese Center for Disease Control and Prevention (CCCPM), Gao Fu, who admitted it at a press conference on Saturday, April 10.

This speech, unusual on the part of a senior Chinese official, brings the spotlight back to the various serums produced in China and already administered to the populations of dozens of countries around the world.

The three main vaccines developed in China are CoronaVac, from the Sinovac laboratory, and two Sinopharm products, developed by the eponymous group.

These are virus inactivated vaccines, that is, the virus carrying the disease has been inactivated or killed "using chemicals, heat or radiation", as defined by World Health Organization.

“Vaccines of this type are older, easy to generate and produce quickly, but their effectiveness is very variable due to the virus inactivation process which denatures viral proteins, often making them poorly immunogenic.

So their success in a new pandemic is quite random and variable, ”emphasizes immuno-oncology researcher Eric Billy.

No phase 3 trial results

The problem is that we do not have the results of the phase 3 clinical trials, since no Chinese laboratory has published them.

Under these conditions, it is difficult to comment on their real effectiveness.

The only data available are interim communications from manufacturers, and they vary widely.

Thus, CoronaVac would be 50% effective in Brazil against all forms of the disease (with or without symptoms), and it would protect 91.25% in Turkey against symptomatic forms.

“But also 56% in Chile, Hong Kong, 65.3% in Indonesia ... In all, we have five different results for this vaccine.

But they were not obtained on the same sample size and under the same conditions, for which it is very complicated to give a precise figure ”, points out Stéphane Korsia-Meffre, medical editor for Vidal and keen observer of the anti-Covid vaccination around the world.

Even more troubling: in Chile, where the strategy is overwhelmingly based on this product, vaccination would be 56.5% effective against infections two weeks after the second dose, but ... only 3% after a single injection.

Something to intrigue many scientists.

“More and more data have emerged in recent weeks showing a low efficacy rate of SinoVac and Sinopharm vaccines

,

notes in Le Monde Jin Dongyan, professor of oncology and virology at the Faculty of Medicine of the Hong Kong University.

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The Sinopharm vaccine produced at the Beijing Institute of Biologics is said to be 80% effective.

Based on phase 3 trials carried out on their soil, the United Arab Emirates had even achieved an efficiency of 86% by the end of 2019.

Except that in March, residents were given a third dose because the first two had not produced a sufficiently strong immune response.

In addition, no Chinese dossier has yet been filed with the European Medicines Agency (EMA) or with its American equivalent, the Food and Drug administration (FDA).

"This is not necessarily an obligation but, if you want to have a marketing authorization in France or in the United States, you must submit a complete file so that the data is analyzed", observes Carine Milcent, CNRS researcher and specialist in the Chinese health system.

“They claim in the various communications to have a good level of effectiveness, but I have never seen a submission report to the EMA or the FDA.

So I remain cautious, ”echoed Eric Billy.

No Chinese vaccine is also under continuous review by the EMA.

A timely study

One question remains: Why is this shattering statement by the director of the China Center for Disease Control and Prevention intervening now?

"Xi Jinping [the Chinese president] is today rather in a position of strength, so I find it hard to think that it is completely by chance that another high-level official is speaking," said Carine Milcent, who rather imagine a motivation with an external goal.

In China, recalls the expert, "the vaccine is not the main weapon to fight against the virus, it is rather the containment measures and the hospitals that are emerging from the ground".

“They never boasted but they had never officially said that their vaccines were ineffective,” observes Stéphane Korsia-Meffre for his part.

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It's the timing that questions. At the end of March, a study was published suggesting that the “prime-boost” strategy - administering different types of vaccines to the same person - would be the most beneficial. And this is precisely one of the avenues put forward by Gao Fu to remedy the lack of efficacy of Chinese vaccines. "The authors of this paper are more in line with the party", slips Stéphane Korsia-Meffre. China would not necessarily be the loser. The CanSino vaccine, adenovirus (like those of Janssen and AstraZeneca), could for example serve as a booster after a first injection of Sinopharm or CoronaVac.

Source: leparis

All news articles on 2021-04-13

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