Influenza D virus—a flu virus primarily found in cattle and pigs—may have greater human infection potential than previously thought, according to new research.
A recent study found that multiple strains of Influenza D virus were able to efficiently infect and replicate in human airway cells and lung tissue models. In some experiments, the virus replicated at levels comparable to human seasonal influenza viruses. Researchers say this suggests the virus has a real potential to cross the animal-human barrier.
What is Influenza D virus?
Unlike the more familiar influenza A and B viruses that commonly infect humans, Influenza D virus was first identified in 2011 and is mainly associated with livestock—especially cattle, which are considered its primary reservoir.
Over the years, scientists have found evidence that the virus can infect several animal species, but human infection has remained uncertain.
Why are scientists concerned now?
The new research suggests that the concern is not simply about the virus entering human cells—but also how it behaves once inside them. Scientists observed that Influenza D virus not only replicated efficiently in human respiratory tissues, but also triggered a relatively weak early immune response. In simple terms, the virus appeared capable of multiplying while initially evading some of the body’s frontline antiviral defenses. That combination is important because it may increase the risk of zoonotic spillover—when a virus jumps from animals to humans.
Have humans already been infected?
So far, there have been no confirmed widespread human infections caused by Influenza D virus. However, previous studies have detected antibodies against the virus in some cattle workers and agricultural workers. This suggests that exposure may already be happening, although it remains unclear whether such exposure causes illness.
Does this mean a new flu outbreak is coming?
Not necessarily. Researchers are not saying that Influenza D is currently spreading among humans. What the study shows is that the virus has biological features that make scientists take its spillover potential more seriously.
At present, the key concern is surveillance—especially at the animal-human interface, where livestock workers may have greater exposure.
Why this matters for public health
Emerging respiratory viruses often begin with isolated animal-to-human transmission events before adapting further.
That is why scientists say Influenza D virus deserves closer monitoring. Understanding how the virus behaves now may help public health systems detect early warning signs before broader transmission becomes possible.
A new study suggests that Influenza D virus can efficiently infect human airway cells, raising fresh concerns about its human infection potential. There is no evidence yet of sustained human-to-human spread, but researchers say the findings highlight the need for stronger surveillance and closer monitoring of flu viruses circulating in livestock.
Leave a comment