Health Secretary Robert F. Kennedy Jr. repeatedly questioned the safety of mRNA vaccines against Covid-19. Scientists who receive funding from the National Institutes of Health are advised to scrub their grants for any reference to mRNA. Across the country, state legislatures are considering bills that ban or restrict such vaccines, one of which describes it as a weapon of mass destruction.
Although mRNA or Messenger RNA has received widespread attention in recent years, scientists first discovered it in 1961. They have been studying it and exploring its promise to prevent infectious diseases, treat cancer and rare diseases.
What is mRNA?
The macromolecules found in all our cells, mRNA is used to enable our DNA to guide every protein that the body builds. It does this by carrying information about DNA in the nucleus into the protein-making mechanism of the cells. Single mRNA molecule can be used to make copies of many proteins, but is eventually programmed to die, says Jeff Coller, a professor of RNA biology and therapy at Johns Hopkins University and co-founder of RNA Therapeutics Company.
How does the mRNA vaccine work?
Currently, among the elderly, there are three FDA-approved vaccines that can use mRNA, two for COVID-19 and one for RSV or respiratory synthesis virus. These vaccines are composed of mRNA strands targeting specific viral proteins.
Suppose you have obtained a Covid-19 vaccine. Package the strands of mRNA into tiny fat particles that enter your muscles and immune cells, says ROBERT ALEXANDER WESSELHOEFT, director of Gene and Cell Therapy Institute RNA Therapeutics at Mass Brigham. The protein plants in the cells then take instructions from the mRNA and produce proteins like they found on the surface of the Covid-19 virus. Your body recognizes that the protein is a foreign body and has an immune response.
Dr. Coller said most mRNA will disappear within a few days, but the body retains its “memory” in the form of antibodies. Like other types of vaccines, immunity gradually fades over time and as the virus develops.
Why are mRNA vaccines now?
In the mid-2000s, University of Pennsylvania scientists figured out how to get foreign body mRNA into human cells without first degrading. This allows researchers to develop it for vaccines.
Currently, the main purpose of such vaccines is to prevent infectious diseases such as Covid-19 and RSV, he said, founding a company that develops RNA therapy. An mRNA vaccine can be performed very quickly, as all components except the RNA sequence remain unchanged in different vaccines.
This feature may help develop the annual flu vaccine, said Florian Krammer, a virologist at the Icahn School of Medicine at Mount Sinai. Typically, scientists decide in February or March where influenza virus strains are included in the vaccine launched in the United States in September. But by then, different pressures may dominate. Dr. Krammer said that since MRNA vaccines are produced faster than current flu vaccines, scientists can wait until May or June to see which strains are circulating.
Are these vaccines at risk?
A common question for patients is whether mRNA vaccines affect their DNA, Dr. Boucher said. The answer is no. Our cells cannot convert mRNA into DNA, which means it cannot be incorporated into our genome.
Dr. Krammer said Covid-19 vaccines may cause symptoms of muscle soreness and heat, but these are usually side effects of the vaccine.
Dr. Adam Ratner, a pediatric infectious disease expert in New York, said it has been more than four years since the COVID-19-19 vaccine was first introduced “without long-term safety signals.” Many parents care about myocarditis, an inflammation of the myocardium, reported as a possible side effect of the vaccine. But, Dr. Ratner said the risk of developing this inflammation in an actual COVID-19 infection or a long-term or multi-system inflammation syndrome in children is much greater.
What other mRNA can be used?
Vaccines using mRNA are currently being studied, including cancer, cardiovascular disease, autoimmune diseases such as type 1 diabetes and rare diseases such as cystic fibrosis, which can lead to excessive, excessive mucus that can block the pneumatic and lungs.
In cancer, the idea is that the mRNA code is a tumor protein recognized by the immune system as a foreign body, telling the body to attack the tumor. In genetic diseases such as cystic fibrosis, it codes as a functional version of insufficient proteins to replace defective proteins and restore mucus to a healthy state.
Earlier this year, a paper in Nature showed that experimental mRNA vaccines for pancreatic cancer caused an immune response in some patients after cancer surgery. Patients who have experienced this immune response live longer without cancer.
Another recent paper suggests that in monkeys, inhaled mRNA therapy may produce cilia-forming proteins, which are cilia proteins, the irlike structures that our airways and move mucus out. These proteins malfunction in a debilitating respiratory disease called primary ciliary dyskinesia.
The study is still in its early stages: the Pancreatic Cancer Study, a Phase I trial, which included only 16 patients, and there may be other differences between the two groups that account for different survival times. Dr. Steven Rosenberg, director of surgery at the National Cancer Institute and cancer immunotherapy expert, explained that the study has a long history, suggesting that interventions may lead to an immune response without actually changing the patient’s outcomes.
Richard Boucher, a pulmonologist at the University of North Carolina at Chapel Hill, noted that for lung disease, it is difficult to safely get particles carrying mRNA into the right cells exactly.
Generally, mRNA vaccines are exciting because they offer hope for disease treatments where previous technologies fail, Dr. Ratner said. But mRNA therapy is still a drug technology like anyone else: in some diseases, he said, “may not in other cases.”
