The vaccines work. Panic is a contagion we don't need.

As panic spreads about the delta variant and supposed vaccine ineffectiveness, the underlying problem is a lack of adequate public health communication about the nature of "adaptive immunity," acquired either by infection with COVID-19 or by vaccination.

The immune system generates several kinds of responses. In the case of actual infection by, or vaccination against, a pathogen, the immune response is referred to as adaptive immunity.

A greatly simplified description of is that immune system cells identify the chemical sequence of portions of the virus and initiate the process of creating or modifying cells that will be capable of recognizing those sequences if they are encountered again, and then disabling or destroying the pathogen.

Adaptive immunity components, including B cells that produce antibodies and T cells that can disable viruses, are present in the bloodstream, but more importantly in the actual upper respiratory tract. Cells referred to as "memory cells" are present in this location and can marshal a response to a recognized pathogen and clear it very rapidly.

But given the weaknesses of so-called PCR testing for COVID, "positives" may be found while this clearing process is occurring. Hence the need for more disclosure on PCR test results for infections in fully vaccinated people.

A too-lenient definition of "fully vaccinated" is also at fault for confusion. Full development of an adaptive immune response, especially the memory cells, may take several weeks. Breakthrough infections should therefore be reported with information on how long after the last dose the infection occurred.

We are all constantly exposed to respiratory pathogens; we breathe them in and exhale them out. COVID-19 isn't going away; we are going to have exposure to it. Calling infections in the vaccinated "breakthrough" is misleading; nothing is being broken through.

So people will be exposed, but will be unlikely to be truly infected or infectious and will be far less likely to suffer serious illness.

The development of adaptive immunity tends to be weaker as we age and is also less potent in those who have certain health conditions or who are generally immunocompromised. This weakness includes a less robust response to vaccinations. We would therefore anticipate that infections in the fully vaccinated will follow the same age structure we saw prior to the vaccination campaigns — that is, most serious illness will be in the frail elderly and those in poor health. And that is what we do see in the data; serious illness among vaccinated people is clustered in the frail elderly.

We are fighting a respiratory virus, these are omnipresent and mutate regularly; therefore vaccine effectiveness is generally lower than against other kinds of pathogens, as we see in flu vaccines. But these COVID-19 vaccines nonetheless appear to be extremely effective, particularly against serious illness. And their effectiveness is likely understated in much of the research, because there often is a failure to break out the unvaccinated but previously infected. Not doing this will cause vaccine effectiveness to appear lower than it actually is.

Finally, the hysteria about the delta variant is unwarranted. Research to date demonstrates that this strain actually results in less serious illness and suggests that it is only somewhat more transmissible. It does not affect children to any greater degree than did prior variants. The vaccines appear only slightly less efficacious against delta. And in addition to the vaccinated population, we have a large number of previously infected people who also possess adaptive immunity.

I believe people can be reassured that the vaccines have substantial effectiveness and will play the key role in minimizing the burden of illness from COVID-19.