  We present results on multifrequency Very Long Baseline Array (VLBA)
monitoring observations of the double-image gravitationally lensed blazar JVAS
B0218+357. Multi-epoch observations started less than one month after the
gamma-ray flare detected in 2012 by the Large Area Telescope on board Fermi,
and spanned a 2-month interval. The radio light curves did not reveal any
significant flux density variability, suggesting that no clear correlation
between the high energy and low-energy emission is present. This behaviour was
confirmed also by the long-term Owens Valley Radio Observatory monitoring data
at 15 GHz. The milliarcsecond-scale resolution provided by the VLBA
observations allowed us to resolve the two images of the lensed blazar, which
have a core-jet structure. No significant morphological variation is found by
the analysis of the multi-epoch data, suggesting that the region responsible
for the gamma-ray variability is located in the core of the AGN, which is
opaque up to the highest observing frequency of 22 GHz.
