Background:
Understanding the illicit cigarette market is important for tobacco control. Tobacco companies have used illicit trade to introduce products to new markets and avoid taxation. The industry lobbies against tobacco control efforts by warning about lost tax revenue from increased illicit trade. This study investigates the change in the illicit cigarette prevalence in urban retailers between 2013 and 2015/2016 within nine countries (Bangladesh, Brazil, China, India, Indonesia, Philippines, Russia, Thailand, Vietnam) across four World Health Organization regions.

Methods:
The Tobacco Pack Surveillance System (TPackSS) systematically collects unique cigarette packs sold in low- and middle-income countries with high tobacco use. In 2015-16, TPackSS returned to countries that changed their health warning regulations since a 2013 pack collection. In each country, one vendor in each of 12 low, middle, and high socioeconomic areas in 3 major cities (4 in India in 2016, 5 in China) was sampled and unique packs were purchased. The absence of country health warning labels was used to identify illicit packs.

Results:
The 2013 sample of 2,034 packs found an illicit sample proportion that ranged from 71% in Bangladesh to 0% in Brazil and Indonesia. The 2015-16 sample of 2,356 packs again found a large illicit prevalence in Bangladesh and minimal illicit pack presence in Brazil's retail environment. A significant increase of 13 percentage points (pp) in the illicit prevalence was observed in Indonesia. A significant increase (11pp) was also found in China and significant decreases were found in Philippines (31pp) and Thailand (20pp). The proportion of illicit cigarettes found in the other five countries did not significantly change. We also report on the origin of the illicit packs.

Conclusions:
Changes in the illicit prevalence of cigarette packs in legitimate urban retailers could be the result of changes in enforcement, brand availability, or consumer demand. Ongoing research is investigating potential causes.