But she said overall alcohol intake rose in the previous lockdown, probably because existing heavy drinkers drank much more than before, lifting the overall average.
Nuanced rules about booze availability in lockdown were probably influencing current drinking patterns, Jackson said.
Wine and beer, available at supermarkets, was generally more accessible during level 4 than spirits.
"Last time, of these exclusive spirits drinkers, a proportion moved to beer and wine and a proportion were able to stop drinking," Jackson said.
Spirits could be purchased in licensing trust areas under strict physical distancing or "one-in, one out" rules, or delivered elsewhere.
Jackson said liquor stores had now greatly enhanced their online and delivery abilities since the first national lockdown almost 18 months ago.
Wine, which can cost lest than a dollar per standard drink, is the most widely-consumed beverage among New Zealand's dependent drinkers, Alcohol Healthwatch says. Photo / 123RF
Some businesses guaranteed delivery by early afternoon, enabling people to get drunk before nightfall.
"Those who are buying alcohol online are more likely to be drinking heavily," Jackson added.
For alcoholics, wine was still the most commonly consumed beverage.
"Almost half of dependent drinkers exclusively drink wine because it's so cheap," Jackson said.
She said people drinking heavily at home in lockdown could present dangers to themselves and loved ones or housemates.
The generally reduced availability of booze affected nationwide drinking rates - but so did stress, boredom, and the desire to zone out from lockdown, Jackson said.
But Jackson said public figures trivialising alcohol abuse were also a problem.
She said it was problematic when broadcasters made flippant comments which effectively condoned or encouraged heavy drinking in lockdown.
"I think it's immaturity. It's the way to get an easy laugh."
When lockdowns were activated, Jackson expected an initial spike in family harm events, and said many of these events were linked to drunkenness.
Some people keen to stockpile booze for lockdown, or party on despite the level 4 announcement, have already run afoul of police.
In Dunedin, a driver aged 32 was breath-tested soon after last week's lockdown started and was more than twice the legal limit.
She told police she'd been drinking at home, but wanted to buy more booze after hearing the lockdown announcement.
The ODT reported more than 100 intoxicated students were found breaching lockdown rules at a party, prompting cops to disperse the crowd and issue a warning to a resident.
The Government last year declined to keep liquor stores open in lockdown, except for places where licensing trusts hold a monopoly on sales, such as West Auckland.
But Cabinet was also warned that deeming liquor stores non-essential could affect people with addiction problems.
In Scotland, deaths from alcohol rose 17 per cent last year and death rates surged when pubs were closed during spring and winter lockdowns, The Times reported.
The World Health Organisation says alcohol does not protect against Covid-19 and its access should be restricted during lockdown.
The WHO says during lockdown, alcohol consumption could exacerbate health vulnerability, risk-taking behaviours, violence and mental health issues.
