In the course of the first year of vaccination against covid-19, between December 8, 2020 and December 8, 2021, 8.33 billion doses of vaccines were administered among 4.36 billion people worldwide.
A recent study published in the journal The Lancet Infectious Diseases estimates that vaccination against covid-19 has prevented as many as 19.8 million deaths. Many of the vaccines that have made this possible (such as Pfizer’s BT162b2 and Moderna’s mRNA-1273) have been messenger RNA vaccines.
These types of vaccines use artificially created genetic material encapsulated in nanoparticles. The mRNA they contain is a kind of instructor, designed to teach our cells how to produce a particular protein, or even just a part of a protein, that acts as an antigen and triggers an immune response within our body. That immune response, which produces antibodies, assists the body in protecting itself against the pathogen.
mRNA vaccines deliver mRNA directly into the cytoplasm of the cell, it does not enter the nucleus, and therefore cannot be incorporated into the genome. The presence of this molecule in the cell is transient as it is rapidly metabolized and eliminated. This makes it a safe and effective procedure.
In addition to being safe, they are created very quickly
Unlike conventional vaccines, these types of vaccines are more easily scalable and can be created relatively quickly because they are based on the genetic code of the pathogen. For this reason, in recent years, interest in this type of technology has grown exponentially to address multiple diseases hitherto untreated (or with ineffective treatments).
Specifically, as of today, 90 leading entities in mRNA technology have projects developing more than 130 mRNA vaccine candidates against different pathologies such as HIV, cytomegalovirus, influenza and rabies. Most are in preclinical stages, but about 25% are already in clinical development.
Without going any further, in March 2022 the company Moderna, Inc. announced its intention to begin initial clinical trials of several mRNA vaccines targeting 15 priority pathogens that pose a public health threat for which they intend to provide a solution by 2025.
From Nipah to the AIDS virus
The U.S. National Institute of Allergy and Infectious Diseases (NIAID) has just announced the launch of a Phase I clinical trial to evaluate the mRNA-1215 vaccine developed by Moderna to prevent Nipah virus infection. The case fatality rate of this virus ranges from 40% to 75%, and the average incubation period is 5 to 14 days, although in some extreme cases it is as long as 45 days. This means that for a long time an infected person can infect others without knowing it.
The experimental mRNA-1215 Nipah mRNA-1215 virus vaccine will be tested in a dose-escalation clinical trial to assess its safety, tolerability, and ability to generate an immune response in 40 healthy adults aged 18 to 60 years.
Along the same lines, the Eclipse trial evaluates the safety and immune response of another experimental mRNA vaccine developed by Moderna intended to protect against Epstein-Barr virus. Recent studies suggest that the Epstein-Barr virus is related to the development of multiple sclerosis, so a vaccine against this pathogen could prevent the disease.
Experimental vaccines could also help in coping with the AIDS virus. NIAID is sponsoring a study called HVTN 302 that examines the safety and ability to induce immune responses against HIV of three experimental mRNA vaccines.
The specific mRNA sequences contained in the vaccines have been designed and developed by researchers at the NIAID-funded Scripps Consortium for HIV/AIDS Vaccine Development (CHAVD) at The Scripps Research Institute and the Bill and Melinda Gates Foundation-funded IAVI Neutralizing Antibody Center at Scripps in collaboration with scientists at Moderna.
In addition to these programs, Moderna has reported that its experimental Zika mRNA vaccine has now reached Phase 2 clinical trial. Two others, against respiratory syncytial virus and cytomegalovirus, have entered Phase 3. Its experimental mRNA vaccine against influenza, called mRNA-1010, which encodes the hemagglutinin of the four types and subtypes of the influenza virus, is in the same phase.
Moderna is also developing several candidate combination vaccines. These include one called mRNA-1073 against influenza and SARS-CoV-2, and another, still in the preclinical phase, called mRNA-1230, designed against influenza, SARS-CoV-2 and respiratory syncytial virus.
Also, experimental mRNA vaccines against glycogenosis type 1 (GSD-I) or Von Gierke disease (mRNA-3745 vaccine), methylmalonic acidemia (mRNA-3705 vaccine), skin cancer (mRNA-4157 vaccine) and refractory solid tumor lymphomas or malignancies (mRNA-2752 vaccine) are under development.
More benefits than uncertainties
There are still important clinical questions about mRNA vaccines, such as their risk-benefit outside a pandemic setting or the durability of protective immunity.
Despite this, the potential is undoubted and the development of technologies for novel mRNA vaccines against emerging, neglected or poorly treatable infectious diseases has only just begun.
This article was originally published in The Conversation. Read the original.