Isn’t that good news? This is a result of the new phase three results of the three-year REFLEXION clinical trial trial for Interferon beta-1a:
This is to prevent , or slow down the progression to full blown unequivocal Multiple Sclerosis diagnostic. The patients involved , as reported by “mscare” , followed this profile
Non definite MS meant one MS like attack experiencing a first clinical episode suggestive of a demyelinating event, such as tingling, numbness, muscle weakness or problems with balance. This with in addition at least two clinically silent brain lesions detected by a brain MRI scan.
While clinically definite meant two attacks. For a classic work on MS diagnosis see the McDonald report 
This is a not exactly your US Avonex or Rebif, but a human serum albumin-free formulation of interferon beta-1a. Such version is only available currently in European Union countries, Australia, Canada and Switzerland, as well as a number of countries in Asia, Latin America, Africa
The risk is that the Interferon is not without possible side effects, see drugs.com . Certainly tingling, numbness, muscle weakness or problems with balance can have other diagnosis than MS.
Then, what about the people “at risk” of MS without clinical MRI tell tale, Should they take it too?
Be sure to discuss the the MS likelihood, risks , as well as the benefits with your doctor.