E visa validity periods do vary from one country to the next based on the reciprocity schedule the U.S. has in place for each country. While 15 months is not the shortest validity period, nationals of most countries that participate in the E visa programs are eligible for visas of at least 24 months and often 60 months.
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This change is unfortunate, as it runs counter to the intention of the E visa classification generally, which is to foster foreign investment and entrepreneurial endeavors in the U.S. Requiring French E visa holders to reapply for E visas so frequently, with all the attendant uncertainty that comes with each renewal, could certainly discourage investment in the U.S. market.