Positive Thinking Might Boost Your Immune System’s Responses to Vaccines, New Research Suggests

Researchers found an association between increased activity in a reward region of the brain—primarily stimulated by hopeful thinking—and heightened levels of protective antibodies after receiving a vaccine

January 23, 2026

person putting bandaid on a child's arm after receiving a vaccine — The findings point to a mental strategy that could help bolster typical medical treatments. Witthaya Prasongsin via Getty Images

Training yourself to expect good things to happen sounds like helpful advice in general. Now, new research suggests that good vibes could have a physical effect on the immune system.

Positive, hopeful thinking that boosts activity in the brain’s reward system might lead to a stronger immune response to vaccination, according to a study published on January 19 in the journal Nature Medicine. The findings hint at a mental strategy that could help bolster typical medical treatments.

“It’s the first demonstration in humans, in what seems to be a causal manner, that if you learn how to recruit your reward system in the brain, the effectiveness of immunization increases,” study co-author Talma Hendler, a psychiatrist and neuroscientist at Tel Aviv University in Israel, tells the Guardian’s Ian Sample.

From March 2020 to August 2022, Hendler and her colleagues worked with 85 participants. Thirty-four of them were trained to increase activity in their brains’ mesolimbic reward system, a pathway comprised of regions called the ventral tegmental area (VTA) and the nucleus accumbens. They did that by recalling meaningful memories, thinking about everyday routines, imagining being successful in the future and performing other mental tasks while lying in a brain scanner. The tool both tracked an individual’s neural activity and showed them in real time whether the desired brain regions were boosted, so that they could adjust their mental strategy accordingly, using a technique called neurofeedback.

“We open a sort of window into an unconscious neural activity,” study co-author Nitzan Lubianiker, a neuroscientist at Yale University, tells Scientific American’s Allison Parshall.

Other participants learned the technique for different brain networks, and some didn’t learn it at all, but still spent time in the brain scanner.

After an individual completed four sessions, they received a hepatitis B vaccine. Each person returned for blood draws two and four weeks later so the researchers could examine how many antibodies their body made to fight the virus. Blood samples had also been taken twice before immunization.

Analyses revealed that as activity in the VTA went up, so did the immune response to the hepatitis B vaccine. The association held up even three months after vaccination, when a subset of participants gave additional blood. When the researchers investigated the mental strategies participants had used, they found a particular connection between positive expectation, or considering the future with hope, and a rise in VTA activity.

Did you know? Possible ties with the placebo effect

Past research has linked activity in the brain's mesolimbic system and positive expectations with the placebo effect, a phenomenon in which the mind tricks the body into thinking a fake treatment is real—and leads to actual healing. The authors of the new study suggest that their findings might present a mechanism underlying the placebo effect.

“These findings highlight the need to consider factors that influence the brain’s reward circuit activity in a clinical setting,” write Kyungdeok Kim, Ben Title and Jonathan Kipnis, immunologists at Washington University School of Medicine who also weren’t involved in the study, in an accompanying commentary in Nature Medicine. The new work, along with other studies hinting at brain-body communication, suggests that “hope circuits” could support immune functions, they add.

Still, the research team emphasizes that positive, hopeful thinking shouldn’t serve as a stand-in for traditional treatments. “The approach we tested is intended solely as a complementary tool that may enhance immune responsiveness to vaccination,” Lubianiker tells the Guardian. “It cannot, and is not meant to, replace vaccines or standard medical care.”

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