Covid-19: Contamination rebounds cast doubt on the effectiveness of Chinese vaccines

This is one of the epistemological puzzles of the moment. Chile, Bahrain, Mongolia and the Seychelles are among the very good students of vaccination with more than 50% of their population having already received two doses. It’s much better than in the United States, France or Germany. And yet, their efforts are not rewarded, since these countries are experiencing significant outbreaks of new cases of Covid-19 contamination, sometimes even in individuals who have been 100% vaccinated.

These four nations have another trait in common: they belong to the large family of countries that have staked everything, or almost, on Chinese vaccines. For some, we should not look much further to explain the apparent Chilean, Mongolian or even Seychelles paradox. “If the vaccines were good enough, you shouldn’t see this kind of phenomenon,” said Jin Dongyan, a Hong Kong virologist, interviewed by The New York Times, which published a long survey on Chinese vaccines, Tuesday, June 23.

Hard reality check

This is far from the first time that Sinopharm and Sinovac, the two main Chinese laboratories engaged in the vaccine race, have been the subject of criticism. They have been criticized for not being sufficiently transparent in the publication of the scientific results of their vaccines, and for not having carried out phase III trials – where thousands of volunteers are vaccinated – before obtaining the authorization. placed on the market by the Chinese authorities.

Unlike Pfizer, Moderna or AstraZeneca, Sinopharm and Sinovac have not carried out a large-scale study either after they began to market their vaccines to reassess their effectiveness, recalls the site specializing in health issues Health Policy Watch.

The misadventures of Chile, Bahrain or Mongolia provide new ammunition to detractors of Chinese vaccines. They would prove that in real conditions “Chinese vaccines are not very effective in slowing the spread of the virus,” writes The New York Times.

Indonesia provided one of the most prominent examples. More than 350 healthcare professionals who received the two doses of Sinovac were contaminated with the Sars-CoV-2 virus in mid-June, says Health Policy Watch. In Seychelles, a third of new cases of Covid-19 recorded in early May concerned individuals who had had their two doses of the Sinopharm molecule, underlines the British channel BBC.

A harsh reality check for the more than 80 countries that have succumbed to the sirens of Chinese vaccine diplomacy, notes the New York Times. “They risk, with China, to find themselves in the group of countries whose population has been fully vaccinated, but which is only partially protected,” said the North American daily.

This is a particularly thorny problem for the countries of Latin America which, after having experienced a particularly trying start to the year 2021 on the front of the epidemic, hoped to get their heads out of the water thanks to Sinovac and Sinopharm. Chile, but also Mexico and Brazil, are among the largest buyers in the world of more than 750 million doses of Chinese vaccines sold worldwide, notes the site Health Policy Watch.

Chinese vaccines, too obvious scapegoat ?

But shooting the Chinese ambulance like this might seem a bit easy. First, because the cases of reinfection after vaccination are not that surprising. “Chinese vaccines are based on traditional technology for developing vaccines, such as those, for example, against polio which are now known to be less effective than those which use the more innovative messenger RNA technology,” like the solutions of Pfizer or Moderna “, underlines Pierre Saliou, associate professor of Val-de-Grâce and specialist in vaccination issues, contacted by France 24.

Tests carried out, both in the laboratory and on human subjects, showed that the molecules of Sinopharm or Sinovac had an efficiency of between 50% and 70%. That’s a far cry from the impressive percentages of Pfizer, Moderna or AstraZeneca (over 90%), but similar to flu shots, for example.

No wonder, therefore, that there are more people infected despite two injections in countries that primarily use Chinese vaccines.

The emergence of variants has also changed the situation. Messenger RNA seems to “produce more antibodies capable of better fighting its mutations than the conventional technology used by Chinese laboratories”, underlines the French virologist.

It is also a bit hasty to blame it all on vaccines. In Chile, for example, “it is clear that there has been a sense of success after only part of the population received an injection which is not sufficient to provide adequate protection. This has created a fake feeling of security and the relaxation of precautions favored a mixture between the vaccinated people and those who were not which was at the origin of a resurgence of contaminations “, analyzes Ian Jones, virologist at the University of Reading, joined by France 24.

Mongolia has even officially exonerated Chinese vaccines from all liability. “We can say that we celebrated too early. My advice to all is to wait until everyone is vaccinated before partying,” said Batbayar Ochirbat, head of the scientific council set up by the Mongolian ministry of Health.

In addition, there is not yet sufficient data to get a precise idea of ​​the reasons for the epidemic resumption in these countries, judge Bernd Salzberger, director of the infectious disease department at the university clinic in Regensburg (Germany), contacted by France 24. “The central question remains, for me, to know what happened with the health system of these countries”, affirms this expert. Have the vaccines been stored in good conditions? Have the deadlines between injections been respected? There are a number of other factors that come into play and can derail a vaccination campaign.

For Pierre Aliou, countries like Chile, Mongolia or the Seychelles “were right to use Chinese vaccines”. The molecules from Moderna and Pfizer may be more effective, but they are also more expensive. For countries with limited financial means, the effectiveness of about 60% of Sinopharm or Sinovac vaccines “is much preferable to nothing at all”. Especially since they still fulfilled their main role: to drastically reduce the number of serious cases and hospitalizations of patients suffering from Covid-19.