It was one of the success stories of the last days: A China-developed vaccine, the company CanSino Biologics showed in the first Tests on 108 volunteers only tolerated, but also triggered the information provided by the researchers in the journal “Lancet,” according to a measurable immune response. However, in a comment in the “New England Journal of Medicine” is now criticism of the vaccine technology, the Interpretation of the data and the decision on the vaccine for the second Phase of more people to allow.
Three groups of Subjects between the ages of 18 and 60 years had either a low, medium or high dose of the experimental vaccine. In the case of “50 to 75 percent” of the subjects, the amount of neutralizing antibodies against Sars-CoV-2-viruses rise by a multiple of Four.
Whether this is sufficient for immune protection, however, is open. “We have no idea what concentrations are necessary, so that a protection of setting,” said Hildegund Ertl, from the centre for vaccine and immune therapy at the Wistar Institute in the USA in the journal “Nature”.
Questionable means of transport for the active substance
In addition, considerable side-effects showed up in the study: 54 percent of those Vaccinated reported pain at the injection site, 46 percent developed, temporarily, a slight fever, fatigue (44 percent), and headache (39 percent).
Serious side effects only occurred in a patient who had received a high dose of the vaccine. He developed for 48 hours, a heavy fever over 38.5 degrees Celsius, severe fatigue, breathing pain, discomfort and muscle.
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The Chinese research group – as well as the Chinese authorities see it as no reason for a (now started) Phase 2 study. CanSino waived in the future, only the high dose of the vaccine candidate.
The vaccine consists of genetic material of the Sars-CoV-2 Virus, which contains the Blueprint for the “Spike”Protein of the “sting”, with which the Virus gains access to human cells.
This genetic material is translated in the cell in the Spike Protein. It will be recognized by the immune system as “foreign” and triggers an immune reaction that leads, ideally, to immunity against complete Sars-CoV-2 Virus. But the Blueprint for the Spike needs to be shoehorned Protein in human cells. As a “Taxi” is used as the Adenovirus “Ad5”.
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The choice of this transport system, Hana El Sahly, Virologist from Baylor College of Medicine in the USA, for “of concern”. In the journal “New England Journal of Medicine” do not warn you that a HIV vaccine in Ad5-based Vaccinated about ten years ago, during Tests, the US pharmaceutical company Merck protected, but perhaps more vulnerable to HIV made.
“A Major Handicap”
The slopes as well, some people had due to previous infections with the widely-used adenovirus antibodies against Ad5, Which was a “major Handicap” for Ad5-based vaccines, says Ertl, because in both China and in the United States, about half of the population has antibodies to Ad5, in Africa, even up to 90 percent.
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In addition, the vaccine produced to solve a quite strong inflammatory response but only a “fairly moderate” immune response. This criticism also shares Ertl: the fact That only half of the subjects who received the middle dose of the vaccine, patients developed anti-body, was “just good”, as well as the T-cell response, the amount of Sars-CoV-2-attack of immune cells, “was not impressive”.
“Despite these concerns,” writes Sahly, who chairs the Advisory Board for vaccine developments in the U.S. FDA, will test the vaccine in China in Phase 2. Great “profit opportunities” in the international race for a Covid-19 vaccine does not give Ertl the CanSino-vaccine but “better than nothing” is he all.