The research, by the school’s Dr Igor Koralnik, was based on a survey of 19 Tysabri users in the US.
Around 56,000 people use the drug on a global basis.
Although the test patients didn’t have PML, the rare brain disease that is a noted side effect of Tysabri usage, the trials claimed instances of the JC Virus (which lies dormant in 90% of humans) shot up in those using the drug.
An Elan spokesperson said the company would openly welcome any detailed scientific learnings which may provide insights into the links between Tysabri and PML. The spokesperson said the Harvard study was inaccurate in its approach.
The spokesperson said: “Research conducted by other independent investigators has shown that the JC Virus in either blood or urine [as tested in this latest study] is not indicative of the risk of developing PML.”
The Dublin and Athlone-based pharma’s share price was down by 2c at €5.29 yesterday.