COVID-19 Vaccines May Offer Strong Long-Term Protection, Oxford University Study Finds

Globally, 8 COVID-19 vaccines are already authorized for emergency use in the general community. These vaccines have been shown to be effective and safe in reducing the risk of complications and death if people are exposed to the coronavirus infection that caused the pandemic. In the scientific community, how long the protection conferred by each vaccine can last is now under investigation. There are dozens of studies underway to find the answer: the protection time could vary depending on the type of vaccine and the particular characteristics of people.

Scientists from the Universities of Oxford, UK, and Cantonal Hospital in St. Gallen, Switzerland, published yesterday a study in the journal Natural immunology which provided key information on viral vector vaccines against the virus. These types of vaccines contain a modified version of another virus (called a “vector”) to give important instructions to cells in the human body.

The advantage of viral vector vaccines, like all vaccines, is that people who receive them are protected without risking serious consequences if they become infected with COVID-19.

The team of researchers from the United Kingdom and Switzerland claim that vectors for adenovirus vaccines, such as the one developed by the University of Oxford and AstraZeneca, they can generate strong long-term immune system responses.

In the work, the authors that this type of vaccines are distinguished by their ability to generate strong and sustained populations of a group of T cells of the immune system, which are cytotoxic lymphocytes. In an animal model, they observed that adenoviruses are able to enter long-lived tissue cells, called fibroblast reticular cells. At the same time, they have formed small, well-organized groups, acting as “training grounds” for these T cells. This mechanism seems to explain why these vaccines can maintain robust immune responses.

One of the authors of the work was Paul Klenerman, Sidney Truelove Professor of Gastroenterology in the Nuffield Department of Medicine at the University of Oxford. The scientist recalled that “millions of people have already received vaccines against adenovirus in the world, not only the Oxford-AstraZeneca, but also the Janssen and the Chinese and Russian versions”.

In the latter cases, Klenerman referred to the Sputnik V vaccines from the Gamaleya Institute of Russia, which are also already produced in Argentina. Argentina’s health ministry is also seeking an agreement to fully produce the AstraZeneca vaccine in the country.

The ultimate goal of vaccination is to induce long-term protection of the immune system through both antibodies and memory T cells. “This research helps us better understand the vaccination process and why the effects on T cells, cytotoxic lymphocytes, are so long lasting,” he said.

Researchers demonstrated that adenoviral vectors can target specific cells – known as stromal cells in tissues such as the lung – generating antigen “deposits” in these long-lived cells. At first, these stromal cells were thought to provide only an inert scaffolding for tissues, but now they appear to be very dynamic cells with an important role in controlling the immune system.

The long-lived nature of cells means that the antigen can “show itself” to the immune system multiple times. This influences the efficient enhancement of the immune response, a critical element in the generation of protective T cells.

Scientists were also able to study other mechanisms that may explain the particular effectiveness of adenoviral vectors, including the key chemical messenger involved in T cell signaling. This is a factor called IL-33. It’s like an “alarm” that goes off when stromal cells receive danger signals.

Factor IL-33 strongly stimulates the metabolism of cytotoxic lymphocytes, resulting in effectively more energetic cells and a highly protective immune response.

Another of the book’s authors, Burkhard Ludewig, professor at the University of Zurich and director of the Center for Medical Research at Cantonal Hospital in St. Gallen, Switzerland, said that “Adenoviruses have co-evolved with humans for a long time and have learned a lot about the human immune system. Viruses are always the best teachers and in this case they have taught us an important lesson about how best to improve T cell responses. “

They consider that the research results could be used for the development of other vaccines for different diseases. “The T cells that come out of these cell training fields appear to have a very high level of ‘fitness.’ Hopefully we can put it to good use to design new vaccines that we still desperately need against diseases like tuberculosis, HIV, hepatitis C and cancers. “

To accelerate in this direction, the researchers reported that will continue to study these particular routes of immunization against emerging pathogens, both in preclinical models and in clinical studies.

Another discovery was published on Wednesday: it was discovered that the COVID-19 vaccine developed by the company Johnson & Johnson and which only requires a single dose can provide protection for at least 8 months. Argentinian researchers say this result could indicate that booster doses might not be needed for a year after receiving the full immunization schedule, as reported. Infobae.

The research was conducted by researchers at Beth Israel Deaconess Medical Center at Harvard University in the United States with colleagues from the Johnson & Johnson Research Center in the Netherlands. The vaccine, whose technical name is Ad26.COV2.S, is manufactured based on a viral vector platform. Twenty people who received the vaccine dose and 5 participants who received a placebo participated. The book was published in the magazine New England Journal of Medicine .

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