The next chief executive and his cabinet has to come up with better long-term welfare policies to stem a growing exodus of social workers, a union says.

The call was made on Wednesday by the Hong Kong Social Workers' General Union as it released the findings of a survey of 553 current and former social workers.

The union found that some 28 percent of the respondents had left their jobs in the past year, citing factors such as better career opportunities elsewhere and emigration.

Of those who stayed in their current jobs, around 45 percent had considered quitting.

The union also spoke to administrators of six non-governmental organisations which normally see an annual turnover rate of 10 to 12 percent, and was told that they had lost up to one-fifth of staff in the past year, including many at middle management level.

Zeno Leung, the union's internal vice-president, said the "alarming" staff turnover and the resulting shortage of manpower will hit organisations hard as the Covid-19 pandemic eases and face-to-face services resume.

He said social service organisations can only do so much to improve the situation, adding that the sector hopes the incoming chief executive and his government will review current policies such as the subvention system, and tackle deep-seated issues.

"We should re-activate the long-term welfare planning for society. It has been suspended for more than 20 years. Today, we do not have that kind of vision or roadmap on what we are going to achieve," he said.

"Whether there's a need for a drastic change, I won't use the term 'drastic', but it's more like [getting things] back to the right track. It may not be that drastic at all, and it need not be achieved in a very short period of time."