So... is this good or bad?
This study looks at how the immune system responds to various infections and stimulants after receiving the BNT162b2 COVID-19 vaccine (commonly known as the Pfizer vaccine).
Before vs. After Vaccination: After getting vaccinated (at a time point labeled "V2 + 28"), the immune system showed a weaker response in terms of specific immune-signaling chemicals (interferon-γ and monocyte chemoattractant protein-1) when exposed to various bacteria and viruses, compared to before getting vaccinated.
Cytokine Changes: Other immune-signaling chemicals (IL-6, IL-15, IL-17) were also generally decreased when the body was exposed to most of these stimulants after vaccination.
Viral vs. Bacterial: Interestingly, these weaker responses in immune-signaling chemicals (cytokines) remained lower for viruses but not for bacteria, six months after vaccination.
COVID-Specific Response: On the other hand, the immune response specifically to COVID-19 (SARS-CoV-2 and its spike proteins) was stronger at "V2 + 28" and remained stronger six months after vaccination.
No Correlation with Antibodies: The levels of COVID-specific antibodies in the blood (measured at "V2 + 28") did not relate to these changes in cytokine responses.
In plain English, the study suggests that after receiving the Pfizer COVID-19 vaccine, the immune system's general ability to signal and react to various infections decreases somewhat, at least in the short term. However, the ability to respond specifically to COVID-19 improves and remains strong for at least six months. These changes in the immune system's signaling ability don't seem to be connected to the level of COVID-specific antibodies in your blood.
Vaccines are made to target a specific or a specific set of pathogens.
The background states that when you gain immunity to the target pathogens, that’s called “antigen-specific adaptive immunity.” When you gain immunity to pathogens similar to, but not, the target, that’s called “cross-protective immunity.” Sometimes, vaccines provide “beneficial off-target (heterologous) effects that alter immune responses to, and protect against, unrelated infections.” It has never been tested if mRNA vaccines also show a similar benefit.
So the study has concluded that children who received the BNT162b2 mRNA vaccine showed increased immune response to pathogens unrelated to COVID-19. Meaning that when children take this vaccine, they are less likely to die from other pathogens too! Which sounds pretty awesome.
I think the linkage with the showing of /increased/ immune response to pathogens unrelated to COVID-19 traces to a finding that, post-vaccine, there is an immediate and general reduction in mortality. (I may have summarised that imprecisely.) The presumption in anti-covid-vaccine-mandate circles is that it is a confounding factor, and the result of biases in how populations are segmented.
But the paper does highlight similar findings in the background ("In high-mortality settings, live-attenuated vaccines are associated with reductions in all-cause infant mortality greater than can be attributed to vaccine-specific protection alone (5–7)."), but it doesn't seem to revisit the topic. Which is a bummer. It would seem to be an important topic to address.
What I find dismaying is that this tiny study is the first and only examination of the impact on broader immune response from the mRNA vaccines (at least, that I have been able to find) after millions of doses were already administered.