There’s a post circulating recently on multiple social media platforms showing a graph with the infection rates of COVID-19 in countries and regions around the world. Most of them show a similar trajectory, or rate of infections, over time rising from the lower left to the upper right on the graph. However, four places stand out because their rates of infection are much lower than the others on the graph: Hong Kong, Singapore, South Korea and Japan. These four countries/regions are circled and the word “masks” is written in large letters. Then there is a second circle around a couple dozen remaining countries on the graph with the words “No masks” beside it.

The implication is clear: Wearing masks is meant to explain the lower infection rates in the four places.

At first glance, the conclusion seems to make sense. Among all the countries and regions in the world, the four places where there is a culture of wearing masks for the prevention of spreading diseases really do stand out. Even during normal times, it is not unusual to see many people wearing masks in East Asia. However, wearing a mask outside East Asia, at least until recently, was unusual enough to attract second glances. And even now, with a full-blown pandemic, in most countries outside East Asia, people generally are not wearing masks.

But if we look a bit closer at the correlation made to mask wearing by the graph, the causative conclusion begins to fall apart. And with this hasty generalization, we learn something about human nature.

To better understand the mistake being made, a look at the specific context of each of the four identified places helps to better understand the complexity of how viruses spread and how news of infection rates is dispersed.

Beginning with Hong Kong, relatively speaking, the measures taken, while not perfect, have been effective, despite a recent surge in cases. Early closing of most border crossings coupled with school and university closings helped Hong Kong flatten the curve compared to many other places. Likewise, Singapore imposed early strict quarantine rules while tracing contacts of those who tested positive for the virus. Further, a little-mentioned fact is that Singapore lies close to the equator with temperatures seldom below 22 C. Although yet to be confirmed about COVID-19, there is clear evidence that corona-type viruses tend to spread much slower, if at all, in hot weather. So local climate may in fact play a significant role. And because Hong Kong is also in the tropics, the spread of the virus may have been slowed here as well.

Although all four places — Hong Kong, Singapore, South Korea, and Japan — seem to have fewer cases of the virus compared to the rest of the world, the reasons for the low numbers varied remarkably from place to place depending on climate, government policy and under-reporting

South Korea presents yet a different story. All reports suggest that their rigorous testing and social isolating presents a textbook case for others to follow. Early drive-through testing and transparent reporting of the spread has earned the country widespread praise.

Finally, Japan’s reported low number of infections may reflect a situation somewhat the opposite to that of South Korea’s approach. In Japan, the criteria to qualify to be tested was highly restrictive until recently. In most of March, Japan was testing just over 1,000 people a day while South Korea was testing 10 times that many despite having less than half the population of Japan. Thus, the low number of reported cases of COVID-19 in Japan was more likely because the test was simply not being conducted very often compared to other countries.

Accordingly, although all four places — Hong Kong, Singapore, South Korea, and Japan — seem to have fewer cases of the virus compared to the rest of the world, the reasons for the low numbers varied remarkably from place to place depending on climate, government policy and under-reporting.

Returning to the question of the effectiveness of face masks, it is certainly reasonable to suggest that they had some preventative effect. For example, for the first time, mask wearing for everyone is being considered in the United States. However, it is not reasonable to make any grand conclusion that the masks were the sole contributor or even the major cause of the low numbers in these four places.

Rather, the quick conclusion that some have arrived at about the value of masks in preventing the spread of the virus is typical of the type of ideas, and sometimes conspiracy theories, being floated at this time of crisis. It is human nature to look for simple answers to complex problems. When we see a correlation, often our first response is to think that it is causative. Obviously, this is a mistake.

In fact, the spread of the virus and our efforts to stop it involve a myriad of factors. Clearly, this is not the time for slapdash thinking.

The author is a commentator on Hong Kong affairs and environmental issues.

The views do not necessarily reflect those of China Daily.