John Miller and Ludwig Burger
Zurich (Reuters)-Vaccines from AstraZeneca, Russia’s Gamalian Institute and Johnson & Johnson’s vaccines fight against the coronavirus with another virus, making scientists worry that if they must be vaccinated every year to fight against new variants, this This injection may lose its effectiveness.
Several Chinese COVID-19 vaccine developers have also used so-called viral vector injections, using harmless modified viruses as a vector or carrier to carry genetic information that helps the body strengthen immunity against future infections.
However, there is a risk that the body will also develop immunity to the carrier itself, recognize it as an intruder and try to destroy it.
Most vector vaccine developers choose to use a harmless common cold virus adenovirus. Director of the Institute of Virology, University Teaching Hospital of Mainz.
He added: “Other types of vectors may have the same problem. Only̵
This may make vector vaccines detrimental to the mRNA vaccines produced by Pfizer and Moderna, and also detrimental to the use of inactivated coronavirus (such as Sinovac’s or the surface spike protein of coronavirus) vaccines, which is the method that Novavax pursues.
Vector immunization is not a new issue, but because companies including Johnson & Johnson anticipate that they may need to receive regular COVID-19 vaccines (such as annual flu vaccines) to combat new variants of the coronavirus, they have been under new scrutiny.
Moderna, Pfizer and its partner BioNTech said in separate statements issued this week that they are studying long-term supplemental injections for new products.
Even if the virus does not have any evolution, it is not clear whether the immune memory induced by the vaccine will eventually be weakened, which requires booster injections.
Scientists who spoke with Reuters admitted that it was impossible to draw a clear conclusion about the ultimate impact of carrier immunity.
Although it turns out to be surmountable, health policymakers will still have to face the question of which vaccines to deploy before possible repeated vaccination and in what order.
A major verification of the vector technology is that Merck & Co approved the Ervebo vaccination against Ebola virus in 2019 and used it during previous African outbreaks-and similar experimental vaccines.
But the carrier’s immunity is related to past failures, including the 2004 Merck AIDS vaccine trial that failed in men who had previously been exposed to the adenovirus used in the vaccine.
AstraZeneca declined to comment. Johnson & Johnson and the Russian Direct Investment Fund (RDIF), which is responsible for overseas sales of artificial satellite vaccines produced by the Gamaleya Institute, did not respond to requests for comment.
One method might be to combine different shots, which is called “mix and match.”
AstraZeneca and its partner Oxford University are experimenting with Russian Sputnik V vaccines, and British scientists are using AstraZeneca’s vaccines to test Pfizer’s mRNA vaccines in a study funded by the British government.
The main motivation of the UK joint trial is to provide flexibility to healthcare providers in limited circumstances, but Oxford vaccinologist Matthew Snape, who is in charge of the project, said that the issue of vector immunization “is very interesting for this study. one of the reasons”.
He added that there are plans to test any anti-vector response by observing how the viral vector performs as a third dose of vaccine compared to alternative vaccines.
Plachter of the University of Mainz believes that in the long run, it may be more practical to switch to a type of vaccine that does not rely on a carrier.
He said: “If after a while, you follow the standard immunization regimen like the flu, then I think you will use other carriers.” AstraZeneca and Gamaleya Institute have sought to overcome the standard COVID-19 two-injection regimen. The challenge of vector immunity. The Russian laboratory uses two different viral vectors to prevent the efficacy from dropping from the initial dose to booster injections, while AstraZeneca and Oxford University use chimpanzee virus vectors, which humans have never been exposed to before.
However, the issue of the third or subsequent shooting remains unresolved.
Ian Jones, a professor of virology at the University of Reading, said: “One of (AstraZeneca’s) biggest selling points is that there is no existing immunity.” “Once there is a COVID vaccine in the world, this will not be the case.”
Since the vectors in the lead vaccine have lost the ability to replicate, the antibodies and T cell responses they produce may not be as strong.
In addition, the COVID-19 vaccine requires only a small vector volume, while gene therapy requires the use of viral vectors as gene repair kits for diseased cells, and because a large number of vaccines need to be injected, it is necessary to closely monitor the immunity of the vector.
Luk Vandenberghe, a gene therapy expert at Harvard Medical School, said: “The injection dose is so low that the induction of immunity to the capsid or virus shell is still low.”
(By Ludwig Burger in Frankfurt, John Miller in Zurich, Kate Kelland and Alistair Smout in London) Reporting with Michael Erman in New York; editing by Josephine Mason and Kirsten Donovan)