Public Health England changed its advice on Friday to allow the reuse of gowns if stocks run low.
NHS England’s medical director Prof Stephen Powis said the previous guidance remained the “best” – but required adequate kit supply.
The communities secretary said 400,000 gowns were arriving on Sunday.
But Robert Jenrick did not dispute the suggestion from a reporter that this would only last NHS England around three days.
And he acknowledged that the “short supply” in areas such as masks and aprons was causing an “extremely anxious time for people on the front line”.
It comes as the UK recorded another 888 coronavirus deaths, taking the total number of hospital deaths to 15,464.
Speaking at the daily coronavirus briefing at No 10, Prof Powis said the government was “working incredibly hard” to supply protective gear to front-line healthcare workers.
PHE guidance previously said healthcare staff treating Covid-19 patients should wear long-sleeved disposable fluid-repellent gowns.
But this was changed on Friday, with PHE outlining three options if gowns were not available as it said “some compromise” was needed “in times of extreme shortages”.
Prof Powis said the former guidance remained “the best possible guidance for the state of the epidemic we’ve reached”.
“In order to ensure that that guidance can be followed, it’s absolutely critical above everything else that we have the supplies of PPE going out to the front line,” he said, adding that the safety of NHS staff was an an issue of “personal” importance.
“I’m a doctor, I’ve worked for many years on the front line and I can absolutely assure you for me and my clinical colleagues, this is very personal,” he said.
“These are my friends, colleagues, extended family.”