Of course, ineffective vaccines are also a serious public health incident, but there is no need to mix the normal risks associated with vaccines with the risks arising from criminal activities, which also should not be blown out of proportion.

As the World Health Organization pointed out, "improperly stored or expired vaccines seldom, if ever, cause a toxic reaction... The risk to children is the lack of protection from the disease for which the vaccine was intended".

Internationally, there are also strict standards for vaccines. Each vaccine must pass many tests and protect over 70 percent of those receiving it without threatening their lives, causing disease or disability, or new-born defects.

Thus the real dilemma concerning vaccines is: Shall we protect people's lives at the risk of one adverse reaction out of a million? Most nations have said yes, and their choices have helped control one disease after another. A typical example is the eradication of smallpox in 1980, which had been a threat to humans for millenniums.

Vaccinations have also helped cut the incidence of polio by 99 percent from 1988 to 2013, although it is on the rise in some African and Asian countries which have resisted vaccine injections for religious or other reasons. That's something the Chinese public needs to reflect on before deciding whether it wants to "boycott" vaccines or not.

Many people argue that poor quality vaccines might lead to adverse reactions. The possibility is very low. A typical example is 2013, when some hepatitis-B vaccine was reported to fail quality standards, China Food and Drug Administration and the National Health and Family Planning Commission investigated and concluded that none of the 17 deaths reported in the incident had anything to do with the vaccine. WHO endorsed that conclusion.

For those who feel suspicious about official announcements, a 2013 essay published in Vaccine, the most respected and authoritative global publication on vaccines and their use, concludes that the number of adverse reaction incidents to vaccine injections in China is similar to those in other countries.

Of course, China has much to do, because its nationwide vaccine adverse reaction monitoring system was not established until 2009. The current scandal shows that supervision throughout the vaccine production and inoculation process－namely production, circulation, sales and usage－must be strengthened because any incident could ruin public's trust in vaccines, which is a bigger risk to public health.

The author is deputy editor-in-chief of the magazine Encyclopedic Knowledge and a former research fellow at the Chinese Academy of Medical Sciences.