>>52576, >>54345, >>54347, >>54349, >>54351, >>54345, >>52590, >>52576, >>52575 pb

COVID-19 Vaccines: Viral Vector Gene Therapy

Understanding and Explaining Viral Vector COVID-19 Vaccines

Several COVID-19 vaccine candidates entering late-stage clinical trials are what is known as viral vector vaccines. These vaccines are likely to be among the COVID-19 vaccines authorized for use in the United States. This page provides background and safety information about these vaccines for healthcare professionals and other vaccine providers, as well as tips for explaining viral vector vaccines to patients.

Key Points to Share with Your Patients

In addition to sharing the following key messages, you can refer your patients with questions to CDC’s COVID-19 viral vector vaccine webpage

Like all vaccines, viral vector vaccines for COVID-19 will be rigorously tested for safety before being authorized or approved for use in the United States.

Vaccines of this type have been well-studied in clinical trials, and viral vector vaccines have been used to respond to recent Ebola outbreaks.

Viral vector vaccines use a modified version of a different virus as a vector to deliver instructions, in the form of genetic material (a gene), to a cell. The vaccine does not cause infection with either COVID-19 or the virus that is used as the vector.

The genetic material delivered by the viral vector does not enter the cell nucleus and does not integrate into a person’s DNA.

A Vehicle for Vaccine Delivery

Many vaccines use a weakened or inactivated form of the target pathogen to trigger an immune response. Viral vector vaccines use a different virus as a vector instead, which delivers important instructions (in the form of a gene) to our cells. For COVID-19 vaccines, a modified virus delivers a gene that instructs our cells to make a SARS-CoV-2 antigen called the spike protein. This antigen triggers production of antibodies and a resulting immune response. The virus used in a viral vector vaccine poses no threat of causing illness in humans because it has been modified or, in some cases, because the type of virus used as the vector cannot cause disease in humans.

A Closer Look at How COVID-19 Viral Vector Vaccines Work

In the development of viral vector vaccines, several different viruses have been used as vectors, including influenza, vesicular stomatitis virus (VSV), measles virus, and adenovirus, which causes the common cold. Adenovirus is one of the viral vectors used in some late-stage COVID-19 vaccine trials.

In viral vector vaccines, a gene unique to the virus being targeted is added to the viral vector. For COVID-19 vaccines, this gene codes for the spike protein, which is only found on the surface of SARS-CoV-2. The viral vector is used to shuttle this gene into a human cell. Once inside a cell, the viral vector uses this gene and the cell’s machinery to produce the spike protein and display it on the cell’s surface.

Once displayed on the cell’s surface, the protein (or antigen) causes the immune system to begin producing antibodies and activating T-cells to fight off what it thinks is an infection. These antibodies are specific to the SARS-CoV-2 virus, which means the immune system is primed to protect against future infection.

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https://www.cdc.gov/vaccines/covid-19/hcp/viral-vector-vaccine-basics.html

>>54783

COVID-19 Vaccines: Viral Vector Gene Therapy

cont…

COVID-19 Viral Vector Vaccines Will Be Rigorously Evaluated for Safety

COVID-19 viral vector vaccines are being held to the same rigorous safety and effectiveness standards external icon as all other types of vaccines in the United States. The only COVID-19 vaccines the U.S. Food and Drug Administration (FDA) will make available for use in the United States (by approval or emergency use authorization) are those that meet these standards. This rigorous review includes large clinical trials and data review by a safety monitoring board.

Viral Vector Vaccines Have Been Used for Recent Disease Outbreaks

Since the 1970s when scientists began creating viral vectors, hundreds of scientific studies have been done and published around the world concerning the creation of viral vector vaccines. A number of human clinical trials have been conducted for viral vector vaccines against different infectious diseases, including Zika virus, influenza viruses, respiratory syncytial virus (RSV), HIV, and malaria. Two Ebola vaccines using viral vector technology have been used in recent Ebola outbreaks in West Africa and the Democratic Republic of the Congo.

Challenges and Benefits of Viral Vector Vaccines

Because humans develop immune responses when exposed to viruses, our bodies can potentially have pre-existing immunity to vector viruses. Since adenoviral vectors are based on natural viruses that some of us might already have been exposed to, the vaccines might not work for everyone. To overcome this challenge, scientists have used uncommon viruses or viruses only found in other species (such as chimpanzees) as viral vectors.

Adenoviruses are often used for viral vector vaccines because they can induce a robust immune response. The adenovirus genome has been well studied by scientists. Adenovirus vector vaccines are easy to design and produce on a mass scale, making them well suited for pandemic response. VSV has been used effectively as a vector for Ebola vaccines, and numerous other viral vectors have shown promise in early clinical trials.

https://www.cdc.gov/vaccines/covid-19/hcp/viral-vector-vaccine-basics.html

>>54783, >>54784

>>52576 pb

Reminder

Published: 09 February 2005

Gene therapy put on hold as third child develops cancer

Small but important: researchers hope that changes to a gene vector will reduce risks to patients.

Scientists have halted clinical trials of gene therapy to treat a rare immune disorder — less than a year after the trials were relaunched following an earlier stoppage.

The trials use gene therapy to treat different forms of severe combined immunodeficiency disease (SCID). The first trial to be stopped was halted in October 2002, and other trials were halted three months later, after two children in the trials developed cancer. But authorities allowed them to resume during the past year because the treatment had cured many children who lack reliable alternative treatments.

Researchers have now halted the trials again, after a third patient was found to have developed cancer. The suspension is a significant setback for the nascent field of gene therapy, because SCID treatment has been its most promising application to date.

The child with cancer was a patient of Alain Fischer of the Necker Hospital in Paris. He has been using gene therapy to treat the X-linked form of SCID, which is otherwise only treatable with bone-marrow transplant and is still often fatal. Fischer's trial restarted last May, and his team has treated one child since then.

But on 24 January, the French medical regulatory authority AFSSPS announced that a child who was treated by Fischer in April 2002 now has cancer.

As a result, Fischer's trial and similar ones in the United States have been halted again. The agency also said that one of the original two patients who had been diagnosed with cancer — both of whom were in Fischer's trial — died last October.

Fischer is now investigating why the third child, who was treated at a later age than the previous two children, developed cancer. The child's cells did not seem to have the same genetic glitch that caused the first two cancers, he says, but he cautions that the analysis is still under way.

Fischer adds that he still believes in gene therapy as a treatment for X-linked SCID, because 15 children treated in this way are still alive, and 14 are doing well four years later. But his group will not treat any more children using its current gene-therapy system, he says. He adds that he plans to change a key step in the treatment by changing the vector — the modified virus that delivers the therapeutic gene to the patients.

“The efficacy is there, but we have to improve on the safety,” Fischer says, adding that this is “not an uncommon situation” in medical research.

https://www.nature.com/articles/433561a>>54783

>>54783

>>52576, >>54345, >>54347, >>54349, >>54351, >>54345, >>52590, >>52576, >>52575 pb

Belmont Principals

Ethical Principles & Guidelines for Research Involving Human Subjects

Scientific research has produced substantial social benefits. It has also posed some troubling ethical questions. Public attention was drawn to these questions by reported abuses of human subjects in biomedical experiments, especially during the Second World War. During the Nuremberg War Crime Trials, the Nuremberg code was drafted as a set of standards for judging physicians and scientists who had conducted biomedical experiments on concentration camp prisoners. This code became the prototype of many later codes[1] intended to assure that research involving human subjects would be carried out in an ethical manner.

The codes consist of rules, some general, others specific, that guide the investigators or the reviewers of research in their work. Such rules often are inadequate to cover complex situations; at times they come into conflict, and they are frequently difficult to interpret or apply. Broader ethical principles will provide a basis on which specific rules may be formulated, criticized and interpreted.

Three principles, or general prescriptive judgments, that are relevant to research involving human subjects are identified in this statement. Other principles may also be relevant. These three are comprehensive, however, and are stated at a level of generalization that should assist scientists, subjects, reviewers and interested citizens to understand the ethical issues inherent in research involving human subjects. These principles cannot always be applied so as to resolve beyond dispute particular ethical problems. The objective is to provide an analytical framework that will guide the resolution of ethical problems arising from research involving human subjects.

This statement consists of a distinction between research and practice, a discussion of the three basic ethical principles, and remarks about the application of these principles.

https://www.hhs.gov/ohrp/regulations-and-policy/belmont-report/read-the-belmont-report/index.html#xethical

https://www.fda.gov/vaccines-blood-biologics/vaccines/emergency-use-authorization-vaccines-explained

Just go ahead and wear the whole box

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