An interesting suggestion may provide an explanation for why the flu and Covid-19 did not strike the United States at the same time, preventing the so-called twindemic that many public health experts had expected.
While masks, social distance, and other pandemic restrictions were effective in keeping flu and other respiratory diseases at bay during the coronavirus outbreak, the assumption is that they were also responsible for the virus’s resurgence after the outbreak was over.
Instead, exposure to one respiratory virus may cause the body’s immune systems to go into overdrive, preventing additional invaders from gaining admission into the airways and causing complications. This biological phenomena, known as viral interference, has the potential to limit the number of respiratory viruses that may be found in a specific place at any one moment.
In terms of an individual level, she said that it is possible for some individuals to get infected with two or even three viruses at the same time. However, according to this idea, at the population level, one virus tends to supplant the others.
In spite of this, she issued a warning, noting that “the health-care system may become overcrowded far before the top limit of circulation is reached, as the Omicron wave has shown.”
Interference with viral replication may be useful in explaining the patterns of infection found in large populations, such as those that may emerge if the coronavirus becomes endemic. However, the study is still in its early stages, and experts are still trying to figure out exactly how it works.
It used to be that influenza was one of the most prevalent severe respiratory diseases each year, before the coronavirus became a worldwide menace. Flu-related medical visits, hospitalizations, and fatalities totaled 13 million in the 2018-2019 season, according to the Centers for Disease Control and Prevention.
The 2019-2020 flu season was winding down when the coronavirus started wreaking havoc throughout the globe, making it difficult to determine if the two viruses were interfering with one another or not. Many specialists predicted that the viruses would clash the next year, resulting in a twindemic that would overwhelm hospitals.
It turned out that their fears were unfounded. Although there was a lacklustre attempt to increase flu vaccines, the number of cases remained remarkably low during the 2020-2021 flu season, since the coronavirus was still in circulation, according to the Centers for Disease Control and Prevention.
Only 0.2 percent of samples tested positive for influenza from September to May, compared to around 30 percent in prior seasons, and influenza-related hospitalizations were at their lowest level on record since the CDC started collecting this data in 2005, according to the agency.
Many specialists credited the flu-free season to the use of masks, social distance, and restrictions on mobility, particularly among small children and elderly individuals, who are at the greatest risk of developing severe flu symptoms themselves. However, the flu numbers did begin to rise again a year later, during the 2021-2022 season, when several jurisdictions had lifted their restrictions, although they remained far lower than the pre-pandemic norm.
So far this year, the flu has claimed the lives of almost five million people, resulting in two million medical visits and less than 65,000 hospitalizations and 5,800 fatalities.
As a result, the coronavirus has continued to dominate the winter months, becoming far more prevalent than the flu, respiratory syncytial virus, rhinovirus, and common cold viruses combined.
However, the pandemic has skewed the seasonal rhythm of the respiratory syncytial virus, which typically appears in September and peaks in late December to early February, according to the Centers for Disease Control and Prevention (CDC). During the whole year 2020, it was at its lowest point, and it peaked in the summer of 2021, when the coronavirus had plunged to its lowest levels since the pandemic’s inception.
While viral infection triggers a complicated chain of immune responses, the very first line of defence comes from a group of nonspecific defenders known as interferons. The researchers discovered that children who already had high levels of interferon had much lower amounts of influenza virus in their systems than children who had lower levels of interferon.
Previous viral infections seemed to have prepared the children’s immune systems to combat the flu virus, according to the research. The study’s lead author, Dr. Thushan de Silva, an infectious disease expert at the University of Sheffield in England, claimed that rhinoviruses were responsible for the majority of the viruses found in the children before they received the vaccination.
This dynamic may account for part of the reason why children, who tend to have more respiratory illnesses than adults, seem to be less prone to get infected with the coronavirus than adults. According to Dr. Guy Boivin, a virologist and infectious disease expert at Laval University in Canada, the flu may also help to prevent coronavirus infections in adults.
In recent research, it has been shown that co-infections with the flu and the coronavirus are very uncommon, and those who had an active influenza infection were about 60% less likely to test positive for the coronavirus, according to Dr. Koenig.
As a result of technological advancements over the last decade, it is now possible to determine the biological basis of this interference. Using a model of human airway tissue, Dr. Foxman’s research team demonstrated that rhinovirus infection increases interferons, which are subsequently able to ward off the coronavirus infection.
Researchers studying common-cold coronaviruses have projected that SARS-CoV-2 would emerge as a seasonal winter illness that will likely overlap with the flu. The pandemic coronavirus, on the other hand, has already shown that it is distinct from its relatives.
When it comes to co-infections, for example, it is seldom observed, but one of the four common-cold coronaviruses is regularly found as a co-infection with the other three.