Companies selling snacks and fast food have been accused of "Covid-washing" by pushing their products on the back of New Zealand's national lockdown.
Companies singled out in the University of Auckland study have defended their marketing, which one major brand says has been "taken out of context".
The study, just published in the journal Frontiers in Nutrition, analysed nearly 1400 social media posts by 20 biggest major behind confectionery, snacks, fast food and non-alcoholic beverages over the period nationwide stay-at-home orders were in place.
It found about 27 per cent of the posts related to Covid-19 themes, of which more than a third linked a brand with community spirit.
Posts picked out in the study included phrases about solidarity like #allinthistogether, "Kia kaha [Stand strong]", from Domino's pizza and McDonald's respectively.
The study also noted how Kit Kat (Nestle) and Whittaker's posts came with "thank you" posts aimed at healthcare workers, produce pickers and street cleaners.
Another 23 per cent of those posts suggested brand-related isolation activities was common, while 22 per cent came with a message that consumption helped people to cope.
A Domino's post told followers: "Not sure who needs to hear this, but you can order Domino's more than once today. It's OK."
Six posts were also found to potentially breach one of New Zealand's advertising standards codes by promoting excessive consumption or targeting children.
Fast-food companies were the most likely to reference the pandemic, with the researchers observing a rapid increase in posts just before the end of level 4 restrictions.
The researchers described the posts as "Covid-washing", which was akin to "greenwashing", where companies used environmental concerns as a marketing ploy.
The study's lead author, Dr Sarah Gerritsen, said Covid-washing portrayed a company as empathetic and contributing in a meaningful way to the pandemic response.
"When, in reality, it was just another strategy to promote products and choices that are detrimental to health."
Gerritsen and her co-authors argued that the findings cast doubt on whether the companies were showing a "due sense of social responsibility to consumers and to society" and did "not undermine the health and well-being of individuals", as required under the New Zealand Advertising Standards Code.
The researchers noted how marketing of unhealthy food and beverages was widespread across multiple online platforms - Facebook in particular - at a time people were isolating and stressed.
An earlier study led by Gerritsen suggested that people experiencing the most stress during lockdown were the most likely to struggle to eat healthily.
"Being bombarded by advertising online undermines our ability to eat well, and during the pandemic these companies were preying on our anxiety," Gerritsen said.
"The misappropriation of social concern about the pandemic in order to promote unhealthy products and build brand loyalty at a time when many people were experiencing heightened stress is unconscionable and undermined public health."
Companies approached by the Herald contended they'd acted irresponsibly.
A spokesperson for Domino's said its social media channels reflected "what is happening within our communities at any given time" and the pandemic was no different.
"Our marketing adheres to all guidelines set out by the Advertising Standards Authority and as an additional step Domino's does not market to children," a spokesperson said.
McDonald's argued the study didn't take into account a "macroenvironment" during lockdown and alert level 3 - and that some of its marketing was in response to publicity around the chain re-opening.
"User generated content and news media coverage built up an anticipation for the re-opening of the likes of McDonald's."
A spokesperson for the company contended that the research showed a "fundamental lack of understanding of how brands operate on social media channels", and claimed some of the study's suppositions were misleading.
"We have attempted to clarify facts, such as organic and paid reach, and the age-gating of all our content to avoid it being seen by children, to these researchers in the past."
Nestle explained that its "thank you" post was a message relating to a donation of 25,000 specially-labelled Kit Kats distributed to healthcare workers, made in addition to $500,000 worth of products to the Salvation Army.