For much of modern medical history, the narrative surrounding infectious disease has been stark: recovery or death. This binary, however, has never fully captured the reality for a significant number of people. Illness doesn’t simply end for them. it lingers, reshaping and sometimes permanently altering their lives.
Vaccines are critical tools in avoiding these debilitating outcomes, not only by preventing initial infection but also by preventing the multitude of post-infectious conditions that can arise months or even years later. Undermining public confidence in vaccines and reducing research funding increases the risk of infections and expands the population left with chronic post-infectious disease – at a time when science should be focused on prevention, diagnosis, and treatment.
The COVID-19 pandemic brought the concept of post-infectious conditions into sharp public focus. Long COVID – characterized by persistent fatigue, exhaustion after exertion, cognitive dysfunction (“brain fog”), headaches, and a range of other systemic symptoms – affects an estimated 10 to 20% of adults and children after their initial infections. For many, these symptoms aren’t minor inconveniences but life-altering disabilities, disrupting work, education, and daily life.
While Long COVID feels unprecedented, it is not. What *is* new is our collective awareness of such conditions and the opportunity to intervene. History consistently demonstrates that major infectious disease outbreaks are often followed by waves of chronic illness in a subset of survivors.
During the 1889-1890 influenza pandemic, often called “Russian influenza,” physicians documented prolonged post-viral syndromes they termed “influenza exhaustion.” Patients reported months to years of fatigue, muscle pain, anxiety, sleep disturbances, depression, and neurological symptoms. The phenomenon was widespread, prompting medical texts dedicated to its description.
The 1918 H1N1 influenza pandemic left an even more devastating legacy. In its wake emerged encephalitis lethargica, a condition marked by brain inflammation and catatonia – a state of unresponsiveness. It also caused profound neurological impairment and coma-like states in some. Between 1919 and 1927, the British Ministry of Health recorded nearly 16,000 cases, with a mortality rate approaching 50%. Of those who survived, only a small fraction fully recovered, many left with lifelong disability. Children were disproportionately affected; in 1924 alone, over 1,000 schoolchildren in England developed the condition, two-thirds of whom never returned to their baseline health.
This pattern continued throughout the 20th century. Poliovirus epidemics, while often resulting in paralysis, also led to post-polio syndrome years or decades later. This syndrome manifested as progressive muscle weakness, severe fatigue, debilitating pain, and, in some cases, paralysis. The unpredictability of who would be affected, and when, remains a hallmark of polio.
More recently, survivors of the 2002-2004 SARS outbreak experienced “Long SARS,” with persistent pulmonary disease, muscle wasting, sleep disturbances, fatigue, and cognitive impairment lasting a year or more. SARS, a close relative of SARS-CoV-2, foreshadowed the post-viral syndrome that would follow COVID-19.
Following the 2014-2016 West African Ebola epidemic, many survivors reported chronic eye complications, musculoskeletal pain, neurocognitive deficits, and profound fatigue, despite having survived a virus with a fatality rate exceeding 40%.
Across time, geography, and pathogens, the lesson is consistent: surviving an infection doesn’t always mean recovering from it. Prevention is our most powerful strategy for preventing chronic disease. Vaccines are indispensable.
Vaccination doesn’t just reduce hospitalizations and deaths; it prevents the downstream risk of long-term medical problems that we still cannot reliably predict, treat, or reverse. Avoiding the infection altogether is the only proven way to eliminate the risk of post-infectious chronic illness.
However, public confidence in this foundation has been eroded. Conflicting messages and policies that deviate from evidence have left many families struggling to know whom to trust. This confusion has real consequences, weakening vaccine uptake, increasing the circulation of preventable diseases, and setting the stage for future waves of chronic illness.
Modern medicine’s advancements weren’t accidental. They stemmed from scientists and doctors embracing data, rigorous study design, and prevention. Vaccines are among its greatest achievements – not only because they save lives today but because they spare lives from being permanently altered tomorrow.
While all medical interventions carry some risk, the risks associated with vaccines are minor, and their profound benefit to human health is unmatched. We are at a pivotal moment, with an unprecedented ability to study post-acute conditions. Modern technology and communication allow us to investigate their biology in ways previously unimaginable. If we’ve learned anything from over a century of pandemics, it’s this: history repeats itself. Abandoning vaccines and evidence-driven medicine won’t make us freer or healthier; it will simply make us sicker.
