Not all vaccines are created equal — some give us lifelong protection against disease after a short period of administration, while others require a regular booster.
It is not easy to predict what the scenario will be for a given vaccine, but a new study, in the journal Nature Immunologyyou may have found a way to predict the duration of immunity from a simple blood test.
It was thanks to vaccines that humanity managed to eradicate smallpoxwhich remains the only human disease for which we have achieved this goal.
The rapid development and launch of COVID-19 vaccines has helped change the course of the recent pandemic, and HPV vaccines are already radically decreasing cervical cancer rates. These are just a few examples.
For some vaccines, a few doses in childhood are enough to guarantee lasting protection. For others, like the seasonal flu vaccine, you need to update your protection every year. But why?
“The question of why some vaccines induce long-lasting immunity and others do not has been one of the great mysteries of vaccine science“, he stated Bali Pulendranprofessor of microbiology and immunology.
In an effort to find some answers, Pulendran and colleagues conducted an investigation in 2022 that defined a “universal subscription” of the early antibody response to various vaccines.
Although this was a step forward in identification of who is likely to produce the best immune response after being vaccinated, the next step would be to try predict how long this immune response might last.
That’s what the team did in their latest study. They started with a vaccine against a virus that is expected to continue to be a hot topic until 2025: the H5N1 bird flu.
50 healthy people were inoculated with an experimental bird flu vaccine, with or without an adjuvant — an ingredient added to some vaccines to increase the immune response, but which does not induce an immune reaction on its own.
During the 100 dias Following the two doses of vaccine, numerous blood samples were collected from the volunteers for in-depth analysis.
Scientists have identified a molecular signaturecaptured in small fragments of RNA inside platelet cells, which was associated with the strength of an individual’s immune response months later.
“What we learned was that platelets are a thermometer for what is happening to the megakaryocytes in the bone marrow,” Pulendran said.
Megakaryocytes themselves have increasingly been shown to play a role in immunitybut they are difficult to analyze, so it is very useful to have the platelets derived from them as an indicator.
To test their discovery, the team also vaccinated mice against bird flu, adding a medicine called thrombopoietin which increases the production of megakaryotic platelets. Mice that got that extra boost recorded higher levels of antibody production against the flu two months later.
In addition to H5N1, the team looked at previous data from 244 people who received seven different vaccines, including seasonal flu, yellow fever and COVID-19.
The same molecular signature was predictive of a longer-lasting immune response for all of these vaccines, suggesting that this could be the universal indicator they were looking for.
Looking to the future, Pulendran suggested that “we could develop a simple PCR assay — one chip of vaccine — which measures gene expression levels in the blood just days after someone is vaccinated. This could help us identify who may need a booster and when.”
The test can also help improve vaccine development and accelerate clinical trialspredicting which vaccine candidates will last the longest, rather than having to follow participants for many months or years.
Thus, this discovery opens the door for some fascinating possibilities.
Teresa Oliveira Campos, ZAP //
