WHY SOME VACCINES PROTECT YOU FOR YEARS AND OTHERS DON’T

For years, scientists have puzzled over why certain vaccines provide lifelong protection, like those for measles or mumps, while others, such as the flu vaccine, need to be administered annually. A groundbreaking study may now have an answer and a potential solution to predict how long a vaccine will remain effective.

Unraveling the Mystery of Vaccine Durability

A team of researchers led by Dr. Bali Pulendran, a professor of microbiology and immunology at Stanford Medicine, has identified a molecular signature in the blood that can predict a vaccine’s durability. This discovery could revolutionize vaccine science, paving the way for personalized vaccine schedules.

“Our study defines a molecular signature in the blood, induced within a few days of vaccination, that predicts the durability of vaccine responses and provides insights into the fundamental mechanisms underlying vaccine durability,” Pulendran explained in a news release.

The Role of Blood Cells in Vaccine Longevity

The research, published in Nature Immunology, shows the critical role of a specific type of blood cell called megakaryocytes. These cells are typically involved in blood clotting, but the study reveals they also influence how long a vaccine remains effective.

Megakaryocytes reside in the bone marrow and produce platelets, small cells that help with clotting. These platelets carry genetic material from the megakaryocytes, which, as it turns out, plays a role in sustaining antibody production for months or even years after vaccination.

“What we learned was that the platelets are a bellwether for what is happening with megakaryocytes in the bone marrow,” Pulendran said.

The Study

The researchers tested their findings on 50 participants who received an experimental H5N1 bird flu vaccine. Some participants were given the vaccine alone, while others received it with an adjuvant—a substance designed to boost the immune response.

Over 100 days, the team analyzed blood samples, tracking genes, proteins, and antibodies involved in the immune response. They identified a pattern in the platelets that was linked to the strength and longevity of antibody production.

To confirm the role of megakaryocytes, researchers administered the bird flu vaccine to mice alongside a drug called thrombopoietin, which increases megakaryocyte activation. The result was a sixfold increase in antibody levels within two months, suggesting megakaryocytes create a supportive environment in the bone marrow for antibody-producing cells.

A Broader Application

The researchers extended their study to include data from nearly 250 people who had received various vaccines, including those for seasonal flu, yellow fever, malaria, and COVID-19. They found the same megakaryocyte activation patterns were associated with longer-lasting antibody responses across all seven vaccines.

Dr Petter Brodin, a paediatrician with the Karolinska Institute in Sweden, commented on the significance of these findings in an editorial. “This raises the tantalizing prospect of developing a practical tool for predicting the longevity of immune responses during vaccine development and clinical trials,” he wrote.

Toward Personalized Vaccination Plans

The implications of this research could be far-reaching. Scientists aim to develop a simple blood test that could predict how long a vaccine will remain effective in an individual. This would allow for tailored vaccination schedules, ensuring that boosters are given only when necessary.

“We could develop a simple PCR assay -- a vaccine chip -- that measures gene expression levels in the blood just a few days after someone is vaccinated,” Pulendran said. “This could help us identify who may need a booster and when.”

Next Steps

The research team plans to explore why some vaccines stimulate higher levels of megakaryocyte activation than others. Understanding this could help scientists design more powerful and longer-lasting vaccines.

2025-01-07T18:21:02Z