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- The effect is deplorable: the German Ebola vaccine supplied to Congo is ineffective
The effect is deplorable: the German Ebola vaccine supplied to Congo is ineffective
The Ebola vaccine that WHO supplies to epidemic-stricken DR Congo is ineffective against the Bundibugio strain, which caused the current outbreak. This was found out by American scientists using a new test system. They analyzed the immune response of patients after being vaccinated with the German Ervebo vaccine and found that it forms protection against the Zaire strain, while the body's response to the Bundibugio strain remains virtually unchanged. But since there is still no specific treatment for it, WHO supplies a drug to Congo against another strain in the hope that it will form cross-immunity from the current threat. Russia also has its own vaccine against Zaire, which, according to the creators, is more effective than its German counterpart, but it is not used for political reasons.
An unexpected discovery
A group of researchers from the United States, together with colleagues from the Democratic Republic of the Congo, made an unexpected discovery that may not even have been part of their plans. The work of the scientists was devoted to testing the multiplex immunoassay system based on microparticles created by them, which is designed to detect an immune reaction after vaccination. It allows you to detect an immune response in the body against several pathogens at once.
In order to test their development, the scientists took 907 samples from patients who had been vaccinated with the German Ervebo Ebola vaccine. The analysis showed that after that they developed immunity from the Zaire strain, for which the drug was created. But the antibody levels against the Bundibugio strain currently raging in Africa were minimal.
"Although reactivity (the body's ability to respond to antigens. EBOV (Zaire strain) increased after vaccination, and reactivity to non-EBOV filovirus antigens (Sudan and Bundibugio strains, as well as Marburg virus) remained relatively constant and below the corresponding thresholds at all sampling points, indicating minimal cross-reactivity in this vaccinated group.", — the researchers wrote in the article.
On August 20, the UN officially announced that DR Congo had requested 70,000 doses of the Ervebo vaccine from the global stockpile of the International Vaccine Coordination Group. This is a WHO-recommended drug against the Zaire strain. And until now, it was not known whether this vaccine was able to protect people from the Bundibudgio strain. It was assumed that this is quite possible due to cross-immunity, when the body's defense against one virus acts on another. However, the results of the American study may cast doubt on this effect of Ervebo, although the scientists themselves note that they did not evaluate the effectiveness of the vaccine, but checked their test system.
Previously, WHO was against the use of Zaire vaccines to combat the current outbreak. However, in the absence of other means, she changed her decision, which was supported by the African Center for Disease Control and Prevention. On August 22, the first batch of vaccine was delivered to Congo — more than 16 thousand doses. Another 20,000 are planned to be sent to clinical trials of its effectiveness against an urgent threat.
The Russian vaccine is more effective
According to the latest data, 5,515 people were infected with Ebola during the outbreak in DR Congo, which began in mid-May. 2,642 of them died, and half of the deaths occurred in the last 20 days. The infection did not bypass 160 doctors — more than 40 of them died. More than 700 patients are currently in medical isolation units.
The study by American scientists was aimed at assessing the body's response to the Ebola virus glycoprotein, which serves as a target for most vaccines. However, as Andrey Prodeus, chief pediatric allergist and immunologist at the Moscow Region Ministry of Health, explained to Izvestia, any test system detects a limited set of antibodies, so Ervebo may be effective against Bundibugio due to those protective body proteins that were not recognized during this analysis.
— Their test system may simply not "catch" the antibodies that the vaccine generates. She sees only specific proteins, not all of them. Therefore, even zero values can be obtained this way. But the vaccine can still provide protection, so it needs to be tested. T-cell immunity can also form, which does not reflect this analysis," said Andrey Prodeus.
In addition to the German vaccine, there is also a domestic Zaire drug, GamEvak, registered in Russia. It can also be effective against Bundibugio. However, there is no information about his trials.
"Purely from a scientific and medical point of view, it is necessary to test and compare the effectiveness of all available vaccines, including Russian ones," the specialist said.
According to Alexander Gintsburg, scientific director of the Gamalea Center, the vaccine created in this scientific organization may have advantages over Ervebo due to repeated booster vaccination.
— Our vaccine has been produced, is in warehouses, and can be delivered to the consumer within 24 hours. And it's more effective than Ervebo because it's dual. The repeat is done on a different medium, does not interfere with the double and allows you to achieve higher titles. We have twice reported to the WHO leadership in Geneva about our drug. The only reason why it is not used is political," said Alexander Ginzburg.
According to him, the Russian drug is approved for use. About 2 thousand Africans received it. Trials of the effectiveness of the Bundibugio vaccine at the current rate of morbidity can be carried out in a month and a half.
Переведено сервисом «Яндекс Переводчик»
