The phrase "a contagion effect" is correct and usable in written English.
It can be used to describe a situation where an effect spreads from one entity to another, often in contexts like economics, social behavior, or health.
Example: "The financial crisis had a contagion effect, impacting markets around the world."
Alternatives: "spillover effect" or "ripple effect".
It was a contagion effect.
"There is a contagion effect," he said.
Researchers who have studied American mass shootings have found evidence of a "contagion effect".
The study also looked at those Facebook users' friends and found a contagion effect — but only among close friends.
Stressed teachers impact students' stress levels through a contagion effect, and since student stress impacts learning, this can hurt the quality of education in the classroom.
You know, when we look at energy policy at a state or for that matter any level, we ask, is there a contagion effect?
Stocks were languishing around lunchtime in New York amid concerns about a possible contagion effect from Brazil's economic woes and a sharp downturn by International Business Machines following the release of Big Blue's earnings report for the fourth quarter.
But, he added, it is hard to "argue convincingly of a possible contagion effect" of any new charges.
Analysts said that even if Europe can agree on the details of a rescue package for Greece, worries will persist about political stability in the country as well as a possible contagion effect on Ireland, Italy, Spain and Portugal.
Still, Mr. Draghi of the E.C.B. is taking an optimistic view, declaring earlier this month that the euro zone economy would recover later in 2013 and that there was now a "positive contagion" effect in play.
Friends exert a "social contagion effect" and I think LGBT people need that effect to counter the negative impact of stigma and discrimination on our health.
