I don’t think the text says that miracles never occurred with the other apostles’ shadows. But Luke, the author of Acts, may have preserved that as emphasis on Peter’s primacy, as he did elsewhere in his own gospel account and elsewhere in Acts.
As well, here is the Haydock Commentary on the verse:Ver. 15. On … couches, meaner beds for the poorer sort. — That Peter’s shadow, &c. Thus was partly fulfilled what Christ had foretold, (John xiv. 12.) that his disciples should do even greater miracles than he had done. (Witham) — St. Ambrose compares with these miracles wrought by St. Peter’s shadow, those which the linen cloths, that had touched the relics of the holy martyrs, also wrought. (Epis. liv.) Si inanis quædam species vacuæ imaginis habere potuit in se vim salutis, quanto plus de corpore meruerunt attrahere salubritatis sacris impressa membris vincula passionis? If the empty appearance of an unsubstantial shadow possessed the power of giving health, how much more efficacy must the chains of the martyrs have drawn from the holy members, which they bound? — In appendice operum. (St. Augustine, serm. cciii.) — St Augustine, speaking of the miracle performed by the saints now reigning in heaven, says: “If the shadow of Peter’s body could afford help, how much more now the fulness of his power? And if then a certain little wind of him, passing by, did profit them that humbly asked, how much more the grace of him, now being permanent and remaining?” (Serm. xxxix. de sanctis.)
. It is clear from the NT that all of the apostles possessed the gift of healing, but as St. Peter was the obvious “chief” of the community, he is the one the masses thought of when seeking these graces…
