It gives a nice glow to send or receive a UNICEF holiday greeting card: you are doing your bit for the world's children. Just how much you are doing, and how little, you can discover from "The State of the World's Children, 1982- 1983," the annual report of the United Nations Children's Fund put out by its executive director, James P. Grant.

Grant, well known in Washington for his work at AID and the Overseas Development Council, is a great packager and promoter of the do-able. In his new report, he offers something eye-popping: how to cut in half, from 40,000 to 20,000, by the year 2000 the number of children who die from malnutrition and infection every day, and how to do this for a mere $1 billion a year, with existing technology and infrastructure, and without further political changes or risks for the Third World nations where the kids now die.

UNICEF's four aces:

1) Oral rehydration therapy (ORT), a new technique developed in Bangladesh using cheap, easy-to-use materials to stop the diarrhea-caused dehydration that is the single biggest killer of children in the world.

2) Universal child immunization, made feasible by scientific advances (more heat-stable vaccines) and by the delivery system of community organizations and paraprofessionals now increasingly in place in the Third World.

3) Promotion of breast feeding, which has declined steeply in recent decades in poor countries, to reduce "the most unnecessary malnutrition of all."

4) Mass use of home child-growth charts to make mothers the more knowing and participatory helpers of their children's health.

These four "low-cost, low-risk, low-resistance people's health actions," as Grant describes them, "do not depend on the economic and political changes which are necessary in the longer term if poverty itself is to be eradicated. They are available now"--given, as always, the political will.

Nor will such a children's "survival revolution" merely run up population growth rates, Grant argues. As parents become more confident that their children will survive, they tend historically to have fewer births.

I heard a roomful of development professionals dissect the UNICEF program for an evening. Basically, no one could lay a finger on it.

But so much for the hopeful side. The sobering side starts from an awareness that economic distress has halted the postwar improvement in global child health. The numbers of children living and growing in ill health are set to increase.

UNICEF's new program centers on improving the use of available food. But as many as a third of the families in need lack the requisite land, job or income. For them, UNICEF supports, with the rhetoric that is its sole recourse in this realm, "political and economic change to allow the poor to both participate in, and benefit from, the increases in production which can most certainly be achieved."

Meanwhile, UNICEF isolates the world's poorest families, finding them caught in a cycle of ill health, low energy and poverty--from which they still could be released by consumer food subsidies targeted on undernourished pregnant women and young children.

Is this getting a little too radical-sounding for you? Is there a bit too much of the proclivity for broad-scale social justice and social engineering that often seems to be mixed with the water up there at the United Nations?

If so, then perhaps you will accept an obligation to spell out your alternative. The unfortunate fact is that the simplest way to remain a moderate and to be regarded as "sound" in the face of great deprivation is to avert your gaze from the conditions that incline many of those who observe them closely to more far-reaching solutions.

In any event, UNICEF finesses that choice in the short run by offering a program within the ideological reach of just about everybody. Think of it: for a lousy billion dollars a year and no revolution, millions of kids can live.