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Three years into the pandemic, COVID-19 is still gaining momentum, triggering wave after wave as cases spike, subside, and then rise again. But this fall, we’ve seen something new, or rather an old one: the resurgence of the flu. In addition, respiratory syncytial virus (RSV), a virus that is usually barely talked about, has surged, causing a ‘triple infection’.
The surge in these old foes was especially noticeable as influenza and RSV all but disappeared during the first two winters of the pandemic. Even more surprisingly, certain versions of the flu may have died out during his early COVID pandemic. The World Health Organization surveillance program has not positively detected a B/Yamagata influenza strain since March 2020. Jude Children’s Research Hospital in Memphis. But “I hope it’s squeezed out,” he adds. Webby says such an extinction would be a very rare event.
But then, the last few years have been a very unusual time for the human-virus relationship, and lockdowns and masks have gone a long way in keeping the flu and RSV from entering the human nostrils. suspect another factor kept them at bay while COVID was raging. This is called virus interference and means that the presence of one virus can block another virus.
Viral interference can occur in individual cells in a laboratory, and in individual animals and people exposed to multiple viruses, but enough people are infected with one virus to pass other viruses. It can occur in whole populations if it prevents large-scale prosperity of the virus. “Looking back over the past few years, I am confident that COVID can definitely block the flu and his RSV,” he says.
This isn’t the first time scientists have observed such patterns. For example, in 2009, the feared virus was swine flu, which passed from pigs to humans in the spring of that year. It seemed to pick up steam in the fall, but suddenly it stalled in some parts of Europe. Rhinovirus, the cause of the common cold and likely spread by children returning to school, played a central role in the series of weeks before swine flu regained control. Influenza strains delayed the typical fall rise in RSV by two and a half months.
running interference
There are many ways interference can occur within the body. One is when two viruses use the same molecule to enter the host cell. If Virus A gets there first and grabs all those molecular doorknobs, Virus B is out of luck.
Another kind of interference can occur when two viruses compete for the same resources in the cell. For example, the machinery for making new viral proteins or the means of escaping the cell and infecting other viruses. “Think of it as a race between two viruses,” he says Webby.
However, the best-understood method of interference involves defense molecules called interferons that are made by the cells of all animals with backbones (and perhaps some invertebrates as well). In fact, the reason interferon got its name in the first place is viral interference. When the cells sense the virus, they start making interferon. And that activates a number of protective genes. Some of the products of these genes function within or at the cell’s borders, preventing additional viruses from entering and blocking already existing viruses from replicating or exiting the cell.
Cells secrete interferon into their surroundings, warning other cells to be vigilant. The result of all this: If a second virus occurs, the cells have already activated their defenses and may be able to shut them down.
