Initial scepticism about plain packs faded amongst smokers and the more supportive a person was, the more likely they were to try quitting, researchers found.
Plain packaging for tobacco products was fully implemented in Australia on 1 December 2012 along with larger graphic health warnings. The new packs had to have branding and trademarks removed except for allowing the brand name in a standard font on the pack as well as large health warnings.
It is difficult to know whether the implementation of standardised packaging led to increased support for this packaging and greater interest in quitting, or whether pre-existing beliefs and/or greater interest in quitting led smokers to be more likely to choose or accept either or both aspects of the new standardised packs.
An international team of researchers from Australia, the UK, USA and Canada, therefore, set out to examine attitudes to the new packs before and after implementation, predictors of change in attitudes, and the relationship between support and quitting activity.
The researchers used data from the Australian arm of the ITC (International Tobacco Control) Four Country Survey, an ongoing prospective study of smokers over time per country looking at what does and does not work in implementing tobacco control policies.
Data from the five most recent annual waves of surveys carried out in Australia for the ITC survey from 2007 to 2013 were examined, collectively involving responses from 6,384 people.
Analysis of the results showed that support for plain packs increased significantly after they were implemented, rising from 28.2% pre implementation to 49% afterwards.
This meant that after plain packs' introduction, more smokers were supportive of them than were opposed - 49% compared to 34.7%.
Those people with a stronger desire to quit were more likely to be supportive of plain packs, as were those who were rated low on a heavy smoking index, and those who believed they were at high risk of future smoking-related harms.
However, support for plain packs was not related to having already experienced smoking-related harm or to the smoker's overall health assessment.
For both the surveys that were carried out immediately before plain packs were introduced and straight after, those people who were supportive of plain packs were more likely to intend to quit in the future - 78% more likely and 68%, respectively.
Opposition to the plain packs mainly came from those people who smoked heavily and those who underestimated the risks, said the researchers, who also found that support was also associated with higher levels of quitting activity.
Since Australia announced it would introduce plain packaging, there had been interest in other countries in having their own similar laws.
The authors said their findings indicated that it was likely that the implementation of such a policy elsewhere would come to be accepted by smokers in other countries.
They concluded: "Support for plain packs has greatly increased among Australian smokers since the implementation of the policy, with now only a minority of smokers remaining opposed, although we cannot be sure as to what extent this is a response to the total standardised packaging initiative rather than just the plain packs aspect."