One after another there have been postings on social media about the "dangers of vaccines" after a network illegally storing and selling vaccines was busted by the police. One of the most popular posts was one titled "Tragedies Caused by Vaccines", which blamed vaccine injections for the deaths and disabilities of 19 children, it was reposted many times accompanied by calls to "boycott vaccines".

What these posts will never tell you is that there is always a slight possibility that children will suffer an adverse reaction to a vaccine. Vaccines are inactivated pathogens, and they work by prompting the human immune system to produce antibodies to fight similar pathogens in the future. While most people do produce the desired antibodies after receiving a vaccine injection, a few, perhaps one in a million, will have adverse reactions because of their specific immunity conditions.

This is what the Japanese call "a demon draws lots", because although the possibility is low the unlucky person suffers a lot. Even if the vaccine is a genuine product, properly stored, there is always that possibility. Sometimes poor quality vaccines or irregular operation during their injection might cause adverse reactions, too, but the probability of that is also very low.

However, that's fundamentally different from the current vaccine scandal in which over 300 suspects sold more than 20,000 improperly acquired and stored vaccine shots, worth more 570 million yuan ($88 million), to health centers in 24 provinces, municipalities, and autonomous regions nationwide.

Vaccines must be kept at a temperature between 2 and 8 degrees Centigrade during storage and transportation, but the illegal dealers failed to do that; as a result, the vaccines they sell are no longer effective.

Those being injected with the vaccine will still get sick when infected with the pathogen the vaccine is supposed to protect against. This might have serious consequences, even cause fatalities, as the vaccines are for protection against serious diseases.

The authorities announced on Monday that those illegally selling the vaccine will be investigated and punished. But punishments should also be given to those in the health departments and the enforcers of the regulations that have failed in their duties, and the holes in the fences must be closed.

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.