As the coronavirus spreads, deaths mount and fears grow across the globe, biotech companies, universities and government agencies scramble – some together, others alone – for a vaccine to contain it.
A number of companies have announced progress. Some, using genetics-based vaccines, delivered samples to health agencies for evaluation.
However, the approval process for vaccines is much more demanding than for most medicines. Even if the samples pass clinical tests without a hitch, production of a usable coronavirus vaccine will probably take 12 to 18 months.
That's because "vaccines are given to healthy people as prevention," says Dr. David Relman, Stanford University professor of microbiology and immunology and senior fellow at the Freeman Spogli Institute for International Studies. "You don't want to make healthy people sick."
Preventive vaccines don’t treat or cure sickness – they prime your immune system to fight a potential disease. Therapeutic vaccines can boost your immune system's effectiveness.
All of this invade-and-defend combat happens on a cellular level, involving germs and cells too small to be seen with the unaided eye.
In this fight inside your body, remember: The bad guys are disease-causing germs, also known as pathogens, including viruses and bacteria.
The good guys are your white blood cells, especially the ones called lymphocytes that produce antibodies.
How vaccines help your immune system
Your immune system keeps you well by recognizing the difference between healthy and harmful cells.
A virus can't reproduce on its own. It infects a host cell, travels to the nucleus and hijacks the cell's genetic material, forcing it to make more viruses.
When harmful pathogens invade and start to reproduce, your immune system recognizes them by their shapes. The pathogens have antigens, which are special proteins that trigger an attack from your body’s immune system.
Immune systems aren't perfect. In some patients, they respond to infections with an overreaction that causes inflammation in the lungs, a condition known as acute respiratory distress syndrome. This has been seen in flu and coronavirus patients.
You get vaccinated by being injected with a safe variation of a pathogen. That mimics an infection. You don’t get sick, though some recipients may get minor symptoms like a mild fever, but your white blood cells produce antibodies to fight that pathogen like a real threat.
These antibodies attach to antigens on the pathogens and prevent pathogens from invading other cells. Antibodies signal other white blood cells, which kill and remove the pathogens.
The problem is, a specific shape of antibody is needed. The human body has billions of white blood cells, each making its own special-shaped antibody. Only a few antibody shapes will be effective against the pathogen.
It can take several days for the immune system to produce enough properly shaped antibodies to kill the invading pathogens. During that time, a fast-acting pathogen, which can replicate billions of copies of itself, is a critical health threat.
Vaccines speed up the process by making the immune system believe it’s being attacked. After a vaccine primes your immune system, a number of white blood cells called memory cells are ready to make antibodies if the real pathogens attack.
"Even years later, you're going to have these memory cells that will jump into gear," Dr. Relman says.
How vaccines are created
There are a variety of vaccines, classified by how they're made. The most common is the inactivated vaccine, which uses pathogens that have been killed or rendered unable to reproduce.
1) A virus is injected into living cells, such as a chicken embryo, which allows it to reproduce. The virus is then placed in a nutrient-rich liquid.
2) Inside the chicken cells, the virus modifies its genes to reproduce. Since chicken cells are different from human cells, the changed virus loses its ability to reproduce in humans.
3) The virus is purified by removing egg proteins and other material. An adjuvant, containing organic compounds or aluminum salts that help trigger an immune response, is added.
4) The virus is killed with heat or formaldehyde.
5) The solution is added to a liquid suitable for injection.
There's an RNA-based vaccine in your future
Other types of vaccines use the nucleic acids DNA and RNA. Used only in clinical trials so far, these vaccines are based on a bit of the pathogen's genetic code.
Researchers say RNA-based vaccines can be developed more quickly, treat a wider range of diseases and could be much easier to manufacture than conventional vaccines.
"RNA vaccines are great if a vaccine has to be built as fast as possible," says Dr. Ivan Martinez, associate professor at West Virginia University's Department of Microbiology, Immunology and Cell Biology and WVU’s Cancer Institute. "It's a technology that could potentially give us a vaccine within a year from now."
RNA is ribonucleic acid, a molecule that regulates cell activity. There are different types, but messenger RNA (mRNA) tells cells how to make proteins. Proteins perform nearly every function in the human body.
China decoded the coronavirus' genetic sequence and made it public Jan. 10. That kicked genetic research into high gear around the world, focusing on the virus' signature protein spikes that circle it like a corona.
"With the sequence of the virus, a spike protein can be made synthetically in a test tube," Dr. Bart Haynes, professor of medicine and immunology and director of the Duke Human Vaccine Institute, told USA TODAY in an email. "Or a gene can be made, either with DNA or messenger RNA."
In DNA or RNA vaccine production, "you skip the entire lab production," Dr. Relman says. "You get injected, and your cells take the RNA and know what to do. They make the antigen directly. And RNA can be synthesized in huge quantities."
In an mRNA vaccine, an antigen's genetic code is copied, and its RNA is injected into the body. The RNA instructs select cells in the body to produce the antigen.
“The RNA is going to express fragments of antigen protein,” which alerts the body's immune system to start producing antibodies, Dr. Martinez says.
Vaccine clinical tests take months
The Food and Drug Administration approves and licenses a vaccine before public use. Vaccines are developed in laboratories and tested on animals before clinical trials with human volunteers.
“Clinical tests focus on safety,” Dr. Martinez says. “Vaccines are given to healthy adults before actual patients get them.”
Tests are conducted in phases. In preclinical tests, the vaccine is tested in animals to measure toxicity, efficiency of dosage and methods to administer it, including oral, injection, intranasal and others.
"If the vaccine protects in animal models, it can be made pure enough to be tested on humans," Dr. Haynes told USA TODAY.
Testing continues with:
Adult volunteers and people with the disease or condition are injected with the trial vaccine and monitored for effectiveness and side effects for several months.
Clinical studies expand to 100 to 300 volunteers with the disease or condition who are about the same age and physical health as those for whom the vaccine is intended. Studies can take several months to two years.
The vaccine is administered to 300 to 3,000 volunteers with the disease or condition and tested for safety and effectiveness over the course of one to four years.
Continuing tests include FDA review and approval to be certain the vaccine is effective and safe for public use. The fourth phase is post-marketing surveillance, which monitors the long-term effects of the vaccine. The vaccine can be taken off the market if necessary.
International effort to create coronavirus vaccine
A number of biotech companies, government agencies, universities and other organizations have partnered across the world in an effort to find a coronavirus vaccine.
One of the largest efforts is coordinated by the Coalition for Epidemic Preparedness Innovations, a global partnership that works with companies, public organizations and philanthropic groups to speed development of vaccines. It's based in Oslo, Norway.
Here's a sample of corporations, government agencies and others teaming up for a vaccine or treatment:
SOURCE USA TODAY reporting; Stanford University; Duke University; West Virginia University; Coalition for Epidemic Preparedness Innovations; National Institute of Allergies and Infectious Diseases; World Health Organization; Centers for Disease Control and Prevention; biocentury.com; vaccinestoday.eu; Department of Health and Human Services; sciencemag.org
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