A severe bout of flu can increase the risk of heart attack by six times within a week, according to a 2018 study in the New England Journal of Medicine.
This finding, highlighted in recent research reviewed by German outlet Welt, underscores how acute infections like influenza and Covid-19 can trigger serious cardiovascular events in vulnerable individuals, even after the initial illness resolves.
The danger lies not just in the fever or fatigue but in the body’s prolonged inflammatory response, which can destabilize arterial plaques and promote clotting — processes that directly threaten heart function.
How flu and Covid elevate heart risks beyond the infection period
Researchers analyzing data from nearly 76 million adults found that a severe case of Covid-19 requiring hospitalization was linked to a 1.24 times higher risk of lung cancer, with similar patterns observed after serious flu infections.
These effects are attributed to chronic inflammation in lung tissue, creating an environment where malignant cells may more easily take hold over time.
For more on this story, see Erythritol and xylitol increase stroke and heart failure risks.
Meanwhile, emerging evidence suggests the shingles vaccine may reduce dementia risk in women by preventing nerve cell damage from the varicella-zoster virus, though this connection remains less definitively proven than the flu-heart link.
Why the cardiovascular impact is easier to detect than cancer or dementia outcomes
According to infectious disease specialist Mathias Pletz at Jena University Hospital, heart-related complications from infections show up quickly because the latency period is short — unlike cancer or dementia, which develop over years or decades.
This immediacy allows researchers to establish clearer causal links between respiratory viruses and acute events like heart attacks and strokes, making the cardiovascular system a sensitive early warning system for infection-related harm.
Who is most at risk for heart complications after flu or Covid?
Older adults and those with pre-existing heart conditions face the greatest danger, as their cardiovascular systems are less resilient to the stress of systemic inflammation.
Can vaccination reduce these long-term risks?
The source does not specify whether flu or Covid vaccines lower the risk of post-infection heart events, though preventing severe illness through vaccination would logically reduce the likelihood of triggering the inflammatory cascades described.
