The 2018 Olympic Winter Games in PyeongChang concluded on Feb. 25 with an elaborate closing ceremony. As athletes, coaches, and staff return home to their respective countries, some are still recovering from illnesses including the common cold. Along with the norovirus outbreak, the cold may have affected the final medal count by compromising the performances of affected athletes. But some day, future competitors may be spared the experience of having their hopes and dreams dashed by a runny nose, sore throat, and body aches.
Reporting from South Korea on Feb. 11, The New York Times detailed some of the unusual measures and precautions taken by athletes and their coaches to avoid getting sick. Leading up to the Games, a Finnish cross country skier pulled his two children out of school, afraid they might come down with a cold that he could contract. And a Latvian luger ate cloves of raw garlic, a move that was probably not effective unless one considers that other people—both sick and not—were likely to keep their distance.
Meanwhile, scientific and medical studies with animals have led to real progress in the search for a safe and effective way to avoid the common cold. And it wouldn’t require people to cordon themselves off from all human-to-human contact.
The goal: A vaccine that guards against rhinoviruses, the 160 different viral strains that are most often responsible for making people sick with the cold. The formulation of a successful vaccine has eluded scientists since the rhinovirus was first discovered in 1956, in tissue from monkey kidneys. And it’s easy to imagine why: It would have to guard against all or most of the 160 distinct rhinoviruses. Of these, 60 were discovered only about 10 years ago. Unlike the influenza virus—of which a dominant strain usually emerges each year (as well as a corresponding vaccine tailored to it)—rhinovirus strains co-circulate around the world.
The cold can risk more than Olympic dreams. In young children, it can cause serious asthma attacks; for people with lung diseases, it can inflame the lower respiratory tract and become life-threatening. For these populations of people who are susceptible to serious complications, an effective vaccine would be an especially welcome development.
For everyone else, inoculation against the common cold would eliminate a nuisance that will cause symptoms that can persist for as long as three weeks. Signs of infection with a rhinovirus closely mirror those associated with the flu: headache, cough, nasal congestion, sore throat, and fatigue. When these symptoms are caused by influenza, they are usually more severe, but even in healthy patients a cold can occasionally lead to more serious health problems including pneumonia and bronchitis
In other words, a vaccine for the common cold must be developed and tested in living organisms. Just as the rhinovirus was discovered in animal tissue, animal research will allow scientists to find a way to prevent it.
In 2008, English scientists surpassed a hurdle that had hampered progress for decades. Many attempts to infect mice with human rhinoviruses had failed because of differences in the human and rodent proteins that are exploited by the virus. As the researchers explained, “the virus couldn’t infect the mouse cell because the receptor—which acts like a door key—wouldn’t let the virus in.” But scientific advancement in gene editing eventually enabled them to create a mouse that could, through its nostrils, be infected with the human version of the common cold.
In 2014, researchers discovered cotton rats can also be infected with the rhinovirus—leading to symptoms and characteristics that closely mimic those in the infected mice. Together, the small animal models have allowed scientists to identify and test some promising vaccines.
“Suitable vaccine candidates can now be evaluated thoroughly before translation to humans.”—Journal of Vaccines and Immunology
Soon, researchers hope to conduct human clinical trials for a vaccine that may offer protection against as many as 100 strains of the common cold. Like the polio immunization created by Jonas Salk in 1955, this rhinovirus vaccine is comprised of multiple strains of inactive (killed) viral particles. In a single shot, the researchers successfully combined 25 inactive rhinoviruses. When administered to gene-edited laboratory mice in 2016, it proved “broadly immunogenic”—producing a robust immune response from the animals that protected them against all 25 strains.
In the same study, 25 additional rhinoviruses were added to the vaccine and tested with rhesus macaque monkeys. Because the common cold cannot be contracted by monkeys (apart from chimpanzees), the researchers couldn’t prove whether the immunization would prevent them from becoming sick with the rhinovirus. Instead, they sought to determine whether the animals would produce antibodies against each strain. If so, it would build the case for their vaccine’s potential to protect human patients.
Of the 50 total rhinoviruses included in the vaccine, the researchers measured 49 corresponding antibody responses in the monkeys. Moving forward, the researchers aim to dilute the remaining rhinovirus strains enough to include them in the vaccine. Then, more studies with animal models will help to confirm whether the immunization remains safe and effective.
One unlucky Olympian, a teammate of the Finnish cross country skier who pulled his sons out of school, became sick with a cold just before the Games began. On Feb. 11, The New York Times reported she was exiled from her team’s housing and required to stay alone in an apartment, where a team physician charted her progress. Thankfully, her condition improved enough that she competed in three events, including the Ladies’ 30km Mass Start Classic, where she placed 18th.
Her predicament is familiar to any healthy person who has prepared for something important—a job interview; a wedding; a vacation—only to have their hopes compromised by a cold. But such an outcome could be prevented one day with a rhinovirus vaccine discovered and refined by research with animals. It’s possible that Olympic athletes as well as regular people born in future generations will never experience the pain of being hindered by the common cold.