All along in medicine, we have described the extremes of ages: the very old and the very young as the most vulnerable especially in the case of infections. Indeed you may have noticed that school-going children have common colds almost every other week with adults catching the same sporadically. The argument has long been that the immunity in these two extremes is not as strong as for human body at its peak immunity.
Come COVID-19 and all of sudden studies are showing that the children are not only less susceptible to virus, but they also develop less severe disease (to be clear, children of all ages have been affected and at least one, a 14 year old boy has died from the virus)
We thank God that our children are relatively safe but what is the scientific reason? There are many theories but this is mine. Starting from the “fact” that children’s immunity is not stronger than that of healthy adults, I look to see what children may have that adults don’t that would confer an advantage. The answer I arrive at, and this is no more than a theory, is vaccines for other illnesses and the concept booster doses in vaccinations.
What vaccines aim to do is to 1. prevent illnesses and 2. result in milder symptoms should the patient catch the disease nonetheless. What this means is that vaccinated individuals are less likely to catch the infection against which they were vaccinated and if they do, it will be less severe. But then, most adults also got the same vaccines the children have right? Yes. But this is where the concept of booster doses comes in. You see, in many vaccines, for as long as one is not exposed to the disease, the immunity acquired from the vaccine tends to wear off with time and a booster dose is required at some point. This may be the case in adults.
Finally, there is the obvious issue that there is currently no vaccine against SARS-CoV-2, the virus that causes COVID-19 and therefore, there is no possibility that any child could ever have got it. This is true. However, the whole theory is that there is an existing vaccine now that is given in childhood that has some efficacy against SARS-CoV-2 and COVID-19. Childhood vaccines cover a number of organisms including viruses such as those that cause Measles, Mumps, Rubella, Polio and hepatitis viruses. In addition, there are non-core vaccines that are increasingly provided to children including seasonal flu vaccines, rotavirus and many other viruses. All these are viruses first before they branch out into their respective families. Some are closer than others, but there are some commonalities across board. It is therefore not inconceivable that a vaccine designed against one organism could be bear some efficacy against another.
Whereas this is just a theory, which in effect amounts to just a hunch not backed by any study, studies into the treatment of COVID-19 already present such possibilities. The drug chloroquine and its relative hyrdoxychloroquine were created for completely different diseases but are now being investigated for their efficacy against COVID-19. Early reports from China have shown promise.
Most theories are not correct but even when they are, they require studies to prove them. Still, I choose to document this view, today, 22nd March 2020, just in case there is merit to it. I am yet to come across an alternative argument that makes sense to me.