Pursuing MD/MS in India after completing your MBBS is called Residency and for the exact same thing, the exam in the US is USMLE. In order to get into John Hopkins after an MBBS,
On average, JHU takes 1-2 international students every session for Residency from all over the globe. There is no fixed procedure for exceptional cases. Most AIIMS students working in JHU complete their residency in the US and worked extraordinarily hard to join elite institutes like JHU as doctors.