After Australia's clean sweep of the One Day International portion of the multi-format Ashes, Healy reported soreness in the same foot that she injured during last year's Twenty20 World Cup.
She will miss Monday night's first T20I against England at the SCG, where the hosts can retain the urn with a victory.
Cricket Australia is still assessing whether she will return for the final two T20Is or one-off Test match of the Ashes series.
"Alyssa has developed mid-foot soreness on the same side as her previous plantar fascia injury following the ODI series," said a Cricket Australia statement.
"She is currently being managed in a boot and will not be available for this evening's game. Cricket Australia's medical team is consulting with specialists to develop an appropriate management plan over the coming days.Â
"Her availability for the remainder of the series will be assessed as more information becomes available."
Healy's absence comes after she was sidelined from the recent ODI series against India with a knee injury.
Beth Mooney looks set to keep wicket in the first Ashes T20I, having done so in recent series against India and New Zealand.
Vice-captain Tahlia McGrath is expected to captain the side against England at the SCG on Monday night.
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