Visually impaired skier Gallagher will train alongside coach Ross Green in the hope they can race together in Canada.
Evans collided with Gallagher in training last month.
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"We don't want to rush her back and risk complications," British performance director Duncan Freshwater said.
The IPC Alpine Skiing World Championships take place from 28 February to 10 March in Panorama.
Gallagher  - who won Britain's first-ever Winter Paralympic gold medal in Sochi last year with Evans - revealed details of January's crash in Austria earlier this month.
Evans - a former British ski racer - is said to be showing signs of improvement but not to an extent where she can consider returning to the slopes.
"We have been advised that she needs a little longer to recover," Freshwater told BBC Sport.
"Charlotte is one of the best guides in the world and it is a huge loss to the team, but the most important thing is for her to recover 100%."
Gallagher and coach Green - who finished 15th in the combined event for Team GB at the 2002 Winter Olympics - qualified to compete in Canada by racing together in Italy last week.
They won a Europa Cup race, albeit in a weakened field of just two pairs of athletes.
The duo are likely to enter all five disciplines in Panorama.
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However, Freshwater says it is a "huge" ask for Gallagher to build up enough confidence to race with Green at a major event.
"Kelly has to have full faith in her guide because they can be travelling at speeds up to 100km/h," he said.
"It is difficult to build up that relationship quickly, but the decision will be left fully down to Kelly and we will support whatever she decides."
One option may be to focus on 'slower' technical events, such as giant slalom, super-G and slalom races, which theoretically carry a lower risk of injury than the speed disciplines of downhill and super-combined.
Paralympic champion Kelly Gallagher's guide Charlotte Evans will miss the 2015 Para-alpine World Championships because of concussion.