With the case of COVID-19 situation, life is slowing returning to normal as Hong Kongers are eager to be back on the streets to shop and dine. It’s not the time to celebrate yet, though, because the city diagnosed another round of new local cases without epidemiological linkage after 16 days of “clean sheets.” The broken streak was a chilling harbinger that it may be too early to relax our preventive measures against the pandemic, and we will have to carry on for an extended period. What is the reason behind this?

Hong Kong is still far away from Herd Immunity

In New York, the epicenter of the American epidemic front, a study was recently conducted to randomly test its residents for COVID-19 antibodies in the blood. It indicated that only less than 20% of the people acquired such antibodies.

In general, it requires at least 70% of the population to have immunity to achieve what is called “herd immunity,” meaning that the immune majority creates resistance of the spread of the virus within a community. (Let us for one moment assume that having antibodies is equivalent to having immunity.) Given our situation was never as bad as New York, it can be postulated the proportion of Hong Kongers possessing antibodies could only be lower. In other words, Hong Kong is unlikely to have achieved herd immunity at this stage.

Elsewhere in the world, Brazil and Russia’s tally are still on the rise. In Asia, situations of our neighboring countries such as Singapore, India and Indonesia are also not under control. As an international city, once Hong Kong resumes air travel, the number of imported cases will likely increase, and in turn it will become more difficult to keep a clean slate.

Hong Kong has gone through a lot in the last 100-plus days, fortunately we managed to contain the virus situation. While we certainly hope that local contraction numbers will soon die down, the re-emergence of local cases was definitely an alert: that served to remind us of the importance of perseverance in the combat with COVID-19. For it will only take one small lapse to lead to a massive rebound, and put all our prior effort in vain.