Why is the vaping illness only being reported in the USA?

The EVALI (E-cigarette-related Lung Injury) outbreak in the United States in 2019 was a public health incident caused jointly by the illegal market, specific additives, and the unique healthcare system of the United States. It occurred sporadically in other countries and regions outside the United States, but did not cause a large-scale epidemic. There are mainly four underlying reasons for this.
?? Key reason: The culprit is "illegal" THC
The main cause is illegal THC products: The investigation by the US CDC (Centers for Disease Control and Prevention) clearly indicates that the real cause of this large-scale disease is not the regular nicotine e-cigarettes, but the THC (tetrahydrocannabinol, the main psychoactive substance in marijuana) products that have illegally added "vitamin E acetate". Vitamin E acetate, as a thickening agent, is used by illegal manufacturers to dilute THC oil for profit. When it is heated and inhaled, it will seriously damage the lungs. This substance has been detected in almost all THC cartridge samples from patients.
?? International Differences: The Difference Between THC Policies and the Illicit Market
This is the key factor that leads to the concentration of cases in the United States.
Product exposure differences: Among American patients, up to 78-92% used THC products; while in the reported cases outside the United States, the proportion of those using THC products was only 24%, and the vast majority (100%) used nicotine e-liquids.
The root cause lies in regulatory differences: The root cause of these differences lies in the completely different marijuana policies. Some states in the United States have legalized recreational marijuana, which has stimulated a large and unregulated underground THC cartridge market. Outside of the formal channels, a large amount of illegal and unregulated "street" THC products are rampant, providing a breeding ground for the use of illegal additives. In countries where THC is strictly illegal, the illegal market is much smaller, and people use more nicotine products with legal sales channels, so the risk environment is completely different.
⚖️ Underreporting and Misdiagnosis: The Underestimated Global Situation
Although EVALI is most concentrated in the United States, this does not mean that other countries are completely risk-free; it might just be that it has not been detected.
The possibility of underreporting: A global case review study found that patients with EVALI outside the United States had longer hospital stays and a lower rate of being admitted to the ICU. This might suggest that in other countries, doctors are not yet familiar with this new disease, which could lead to missed diagnoses or misdiagnoses.
Masked by "COVID-19": Many international case reports were published in 2020-2021. Their clinical manifestations (such as fever, breathing difficulties, abnormal lung CT images) were highly similar to those of COVID-19. At that time, they were likely to be primarily attributed to COVID-19 infection, and thus were not identified as EVALI.
The existence of international cases: EVALI is not an "exclusive" American phenomenon. There have been confirmed or highly suspected cases reported in multiple countries such as Canada, the United Kingdom, Germany, and Japan. Although the number is much smaller than that in the United States, it is sufficient to prove that this is a potential global risk.
?? Additional factor: Robust but "late" medical monitoring
Strong monitoring network: The United States has a robust public health monitoring system. When the first cases emerged in the summer of 2019, the CDC promptly issued a nationwide alert and established unified diagnostic criteria, which led to a large number of cases being "actively discovered" and reported, intensifying the impression that the cases were concentrated in the United States.
?? Summary
In conclusion, the reason why the EVALI epidemic mainly occurred in the United States was not due to the nicotine e-cigarettes themselves, but rather the unique marijuana policies in the US that gave rise to a large illegal THC cartridge market. Illegal merchants added dangerous vitamin E acetate to these cartridges for profit, ultimately leading to this public health crisis.
Although there have been EVALI cases in other countries as well, due to the relatively low usage of THC and possibly due to insufficient diagnosis or confusion with COVID-19 symptoms, the actual number of cases has been underestimated. This reminds us that the risks associated with e-cigarettes are closely related to the product source, composition, and regulatory environment. No matter where one is, products obtained from unknown sources, especially those containing THC components, may conceal unknown health risks.