![[Adobe Stock]](https://sp-ao.shortpixel.ai/client/to_webp,q_glossy,ret_img,w_750,h_375/https://www.psypost.org/wp-content/uploads/2025/09/brain-mental-health-750x375.jpg)
Recent declines in global immunization rates are causing a resurgence of infectious diseases that can severely damage the human nervous system. A new review article published in Nature Reviews Neurology warns that this trend threatens to undo decades of progress in public health. The authors argue that losing control of these preventable illnesses will lead to a rise in brain infections, paralysis, and long-term disability.
The human nervous system is particularly vulnerable to certain pathogens. These germs are described as neurotropic, meaning they are capable of infecting nerve cells. When vaccination rates are high, communities achieve herd immunity. This protects vulnerable individuals who cannot receive vaccines. However, coverage has dropped since the COVID-19 pandemic. This decline has allowed outbreaks to occur in regions where these diseases were previously under control.
Felicia C. Chow, a researcher at the University of California, San Francisco, led the team that conducted this review. Chow and her colleagues aimed to document the specific neurological risks associated with this drop in immunity. They examined data on how these diseases affect the brain and spinal cord. They also analyzed the social and political factors preventing people from getting vaccinated.
One of the primary threats identified in the review is measles. Many people view measles as a simple rash and fever. However, the virus can enter the central nervous system. This causes encephalitis, which is a dangerous swelling of the brain. The review notes that roughly one to three out of every 1,000 children with measles will develop this complication. The consequences are severe. Many of these children die. Others survive but suffer from permanent brain damage.
There is also a long-term danger associated with measles. A fatal condition known as subacute sclerosing panencephalitis (SSPE) can develop years after the initial infection. This disease involves a slow degeneration of the nervous system. It is always fatal. The risk of developing SSPE is higher than doctors previously thought. It is most common in children infected at a very young age. As vaccination rates fall below the level needed for herd immunity, cases of this delayed neurological disease are expected to rise.
Poliomyelitis, or polio, represents another significant neurotropic threat. This virus was once on the verge of eradication. It attacks the spinal cord and can cause permanent paralysis. Most infections are mild. However, the virus can destroy motor neurons in young children. This leads to acute flaccid paralysis, where muscles become weak and floppy.
The review highlights that polio is returning in areas with political instability. Conflict and war disrupt vaccination campaigns. This allows the virus to spread again. Additionally, survivors of the initial infection face challenges later in life. Post-polio syndrome can emerge decades later. It brings new muscle weakness, pain, and fatigue. This demonstrates that the neurological damage from a missed vaccine can last a lifetime.
Bacterial meningitis is another major concern discussed by Chow and her team. This is an infection of the membranes surrounding the brain and spinal cord. It is often caused by bacteria such as Neisseria meningitidis or Streptococcus pneumoniae. These infections can be rapidly fatal. Even with treatment, survivors often face serious consequences. The review indicates that one in five survivors is left with lifelong disabilities. These can include hearing loss, seizures, and difficulties with memory or speech.
Vaccines have historically reduced the number of meningitis cases. However, the bacteria are evolving. A phenomenon called serotype replacement is occurring. This happens when a vaccine eliminates the most common types of bacteria. Other types that are not covered by the vaccine then grow to take their place. This creates a moving target for public health officials.
Japanese encephalitis virus presents a growing risk in Asia and the Pacific. This virus is spread by mosquitoes. It inflames the brain. Most cases are mild, but severe cases have a high fatality rate. Among those who survive severe infection, nearly half suffer from long-term neurological issues. These include recurrent seizures and paralysis. Climate change is expanding the habitat of the mosquitoes that carry this virus. This puts more populations at risk.
The authors also address the reasons behind the falling vaccination numbers. They utilize a model called the “three Cs” to explain vaccine hesitancy. The first C is confidence. This refers to trust in the safety of the vaccine and the system that delivers it. The second is complacency. This happens when people do not perceive the diseases as a real threat. The third is convenience. This involves physical and economic barriers to accessing shots.
Misinformation plays a large role in eroding confidence. The authors note that false claims about vaccine safety spread easily on social media. For example, some people fear that vaccines cause neurological problems. The review examines this fear objectively. It acknowledges that vaccines can have rare side effects. Guillain-Barré syndrome is one such rare condition where the immune system attacks the nerves. However, the data shows these events are extremely uncommon. The neurological risks from the diseases themselves are far higher.
Inequity is another major barrier. People in low-income countries often lack access to vaccines. This is due to poor infrastructure or cost. Geopolitical conflicts also play a role. War zones are difficult for health workers to reach. This leaves children in these areas unprotected. The review points out that recent polio outbreaks have occurred in such unstable regions.
The researchers discuss new technologies that could help. One promising area is mRNA technology. This was used successfully during the COVID-19 pandemic. These vaccines use a genetic code to teach the body how to fight a virus. They can be developed and produced much faster than traditional vaccines. This speed is helpful for responding to new outbreaks.
Another innovation involves nanovaccines. This technology uses microscopic particles to deliver the vaccine into the body. These nanoparticles can protect the vaccine from heat. This is important for delivering shots to remote areas without reliable electricity for refrigeration. These tools could make it easier to reach underserved populations.
However, technology alone is not the solution. The authors argue that public trust must be rebuilt. They suggest that health education needs to be improved. Doctors need to communicate better with patients. They should acknowledge fears while presenting facts. Community leaders can also help bridge the gap. Engaging with religious or local figures can help increase acceptance of vaccines.
The review has some limitations. It relies on existing data, which may be incomplete in some regions. Surveillance systems in developing nations are often underfunded. This means the true burden of these neurological diseases could be higher than reported. The authors also note that bacterial resistance is a growing problem. Future research will need to focus on how bacteria adapt to vaccines.
There is also a need for more research into how to effectively combat misinformation. The current strategies are not working well enough. Understanding the psychology behind vaccine refusal is necessary. Without addressing the human behavior element, new vaccines will not be effective. The authors conclude that a coordinated global strategy is required. This strategy must combine new technology with social outreach.
The paper emphasizes that the neurological damage caused by these diseases is preventable. The tools exist to stop measles, polio, and meningitis. The challenge lies in ensuring these tools reach everyone. Failing to do so will result in a generation of children facing avoidable brain injuries and paralysis. The connection between declining vaccination rates and neurological health is clear. The medical community is urging immediate action to reverse this trend.
The study, “The global threat of vaccine-preventable neurological diseases,” was authored by Felicia C. Chow, Julia Granerod, Carla Y. Kim, Temesgen Nurye, and Kiran T. Thakur.
