Just in time for New Year’s Eve revelry, scientists at the Oregon National Primate Research Center have added a scientific underpinning to the new-old observation about the health benefits of moderate alcohol consumption. The news is another step in the rehabilitation of alcohol, an erstwhile bad guy.

Public health experts long ago made the observation that moderate drinkers, who imbibe a glass or two a day, seemed to live longer than teetotalers and certainly longer than their heavy-drinking, liver-scarring counterparts. The irony of this inversion of grandmotherly advice has invited public display of a very satisfying nyah-nyah for at least a generation, as well as a growing distrust of medical advice about just about everything. If doctors can change their minds about drinking, what’s left?

The Oregon researchers, writing in the important medical journal Vaccine—a British publication that is the official house organ for the Edward Jenner Society, among other groups—reported the results of an interesting if rather odd study. Involved were 12 rhesus macaque monkeys, pure ethanol, and vaccination with a variant of Jenner’s age-old winner, cow-pox. A strange set of bedfellows, to be sure.

The research group has been working for years to understand the immunologic consequences of heavy drinking, focusing on the inflammatory response in sober and chronically drunk monkeys. They have made some early insights into the specific perturbations of the chemicals, called cytokines, that regulate inflammation at the microscopic level.

As part of their new work, the researchers vaccinated 12 monkeys with a variant on cow-pox, called “modified vaccinia Ankara,” a weakened version of the standard smallpox vaccine given to humans. They then examined two groups: One group of four monkeys drank sugar water while the other eight primates went out and drank as much as they wished. Oddly, some of the macaques hit the bottle pretty hard—actually a solution of 4 percent ethanol, more or less the alcoholic content of beer—while others only sipped and enjoyed.

The researchers divided the drinkers according to the blood level found from serial testing across several months. The heavy drinkers had levels that would get their driver’s license suspended in most states, while the moderate drinkers had a detectable but legal amount. The authors did not speculate about why some macaques drank heavily and others did not—perhaps, though, life in the primate colony is not without its stresses and disappointments, its highs and lows, its romantic entanglements.

After seven months of potentially dissolute living, the researchers then revaccinated the group of eight drinkers and measured immune response to the vaccine several ways. For the most part, they found that heavy drinking is bad news. Every determination of immunity was drastically compromised in the chronic alcoholic macaques, whereas the moderate drinkers resembled the abstemious primates. In one or two determinations, the immune function of the moderate drinkers appeared superior compared not only to the heavy drinkers but to the nondrinkers, as well. This finding, though somewhat subtle and of uncertain clinical significance, made the news splash by suggesting that the observed advantage of moderate drinking may derive in part from the tonic effect of alcohol on that vast complex Rube Goldberg apparatus called the human immune system.

The news is a small but real step forward for science and a smaller step for mankind. The problem, though, is that in the black or white news world, the “drinking is good for your immune system” trope is simply irresistible. Soft-core porn is, after all, not the only place with 50 shades of gray—science and medicine, too, live in an infinite mid-zone, free (God knows) of erotic potential but chock-full of perplexing findings that resist easy summary. There is little room, even in the infinitely capacious world of the Internet, to articulate that massive gray middle, to declaim that “moderate drinking may be sort of good for a thread or two of the complex immune system found in macaque monkeys held in captivity and fed pure ethanol.”

Which means, more simply, that this New Year’s Eve, as with every other night, there is no drinking loophole to be found. A little bit remains OK, and a lot simply is not. And should you spot some tipsy rhesus macaques zig-zagging their way back to the Primate Center, you need to hand over your car keys.