SARS-CoV-2 as a Flu-Like Virus
SARS-CoV-2, the virus responsible for COVID-19, is frequently characterized as a flu-like virus due to the high degree of similarity in symptoms between the disease it causes and classical influenza ("the flu"). Both COVID-19 and influenza primarily lead to acute respiratory illnesses and share a common set of clinical features, including fever, cough, sore throat, runny nose, headache, muscle aches, fatigue, and chills. These overlapping symptoms create substantial difficulty in distinguishing between the two diseases based on presentation alone, which is why public health authorities commonly refer to COVID-19 as a flu-like respiratory illness. The similar mode of transmission, mainly via respiratory droplets and aerosols, further reinforces the classification of SARS-CoV-2 as a flu-like virus.
Symptom Similarities Between COVID-19 and Influenza
Across the medical literature, it is well-established that COVID-19 and influenza induce nearly identical clinical complaints in most cases. Both can present with a sudden onset of fever, nonproductive or dry cough, sore throat, nasal congestion or runny nose, headaches, fatigue, and muscle or body aches. Symptoms such as tiredness and chills are commonly reported in both conditions, making the initial stages of COVID-19 difficult to distinguish from typical seasonal influenza or other so-called “flu-like” illnesses based solely on symptomatology. Diarrhea, vomiting, and mild respiratory discomfort, while less frequent, can occur in both COVID-19 and influenza infections. This extensive overlap in presentation is what prompted clinicians and public health experts to adopt the terminology of "flu-like virus" for SARS-CoV-2.
The Existence of Countless Flu-Like Viruses
SARS-CoV-2 and influenza viruses are but two examples from a vast array of pathogens capable of causing flu-like symptoms. In nature, there exist numerous viruses that similarly manifest with fever, cough, muscle aches, headache, sore throat, and fatigue—collectively known as flu-like or influenza-like illnesses. These include not only the many strains of influenza (types A, B, C, and D) and several coronaviruses but also adenoviruses, respiratory syncytial virus, rhinoviruses, parainfluenza viruses, and more. Seasonal epidemics of flu-like illnesses are a recurrent global challenge, reflecting the widespread prevalence and genetic variability of these viruses. Given the diversity and mutability of these pathogens, there are effectively countless flu-like viruses circulating globally at any given time.
Decades of Vaccine Efforts Have Not Achieved Eradication
For decades, public health efforts have focused on developing and deploying vaccines to combat flu-like viruses, with influenza vaccines being updated annually to target circulating strains. The initial and ongoing aspiration underlying these vaccination campaigns—both for influenza and, during the COVID-19 pandemic, for SARS-CoV-2—has been the eradication of viruses that cause severe respiratory disease and pandemic threat. Despite significant reductions in morbidity, hospitalizations, and deaths thanks to vaccines, complete eradication of these viruses has never been possible. This failure is primarily due to the rapid mutation rates of viruses like influenza and SARS-CoV-2, frequent antigenic changes, and the existence of animal reservoirs that continuously reintroduce the virus into human populations.
Unlike some non-flu-like viruses for which vaccines have led to eradication or near-elimination, flu-like viruses continue to circulate despite vaccination programs, requiring ongoing annual immunization and public health vigilance. Global eradication—the permanent removal of the virus from nature—remains a theoretical goal but, in practice, has never been realized for any of these rapidly evolving respiratory viruses.
Vaccination Goals: From Eradication to Addressing Pandemic Fear
At the outset of vaccine development, the overarching goal has traditionally been eradication, aiming to entirely eliminate flu-like viruses such as those that cause COVID-19 or influenza. However, as scientific and public health communities have encountered the realities of recurring mutations and zoonotic reservoirs, the primary objectives shifted toward control, minimizing severity, and protecting the vulnerable.
During the COVID-19 pandemic, a unique and pressing problem emerged: fear. Widespread anxiety and fear of infection caused much of the global population to retreat from normal societal participation, with people staying at home, workplaces and schools closing, travel halting, and economic activity grinding to a near stop. This pandemic-induced fear risked precipitating not only a public health crisis but also a profound and potentially catastrophic societal and economic collapse. The cessation of widespread societal participation left entire sectors—such as retail, hospitality, travel, education, and even essential services—crippled, threatening the social fabric and the economic systems upon which daily life depends.
The Vaccine as the Solution to Pandemic Fear and Societal Paralysis
In this extraordinary context, the vaccine was presented not only as a medical solution but as the only viable strategy to address the pervasive societal fear triggered by SARS-CoV-2. The message from public health authorities and governments was clear: broad, rapid vaccination adoption would make it safe for people to return to their jobs, schools, and social activities, thereby restoring societal function and economic stability. Vaccination promised to reduce the risk and—most critically for the collective psychology—eradicate the fear that had locked down entire nations.
Messaging strategies explicitly linked vaccination to the promise of a return to normalcy, emphasizing that getting vaccinated was not merely an individual health choice but a collective action for societal recovery. As vaccination campaigns reached more people, evidence showed that vaccinated individuals reported a substantial reduction in their fear of illness, allowing them to resume participation in community and economic activities.
Restoration of Societal and Economic Participation: The Role of Collective Action
The effectiveness of vaccination in reducing fear and enabling societal re-engagement was not just a matter of individual psychology, but also a matter of economic survival. Governments and organizations highlighted that only by overcoming fear together could society avoid collapse and maintain the essential continuity of daily life. The slogan "We're All in This Together" became a global rallying cry, aiming to unify the population in the collective effort to receive the vaccine, reduce fear, and restore social and economic participation. This message stressed that, although the fear was real and justified, society and the global economy simply could not be put on indefinite hold without enduring devastating consequences. Participation was necessary for survival, not just of individuals but of communities, nations, and the global order.
The Essential Truth: Fear Cannot Suspend Humanity Indefinitely
Ultimately, humanity’s collective experience with SARS-CoV-2 as a flu-like virus reinforced an immutable truth: while fear is a natural and rational response to a pandemic, life cannot be paused indefinitely in the hopes that fear will resolve on its own. The unique contribution of the COVID-19 vaccines was their capacity to quell this fear, mobilize people for collective action, and thereby avert the collapse of society and economy. By offering a scientifically validated path forward, vaccination enabled society to move from paralysis and anxiety back to engagement, productivity, and hope for the future. The slogan "We're All in This Together" exemplified the collective determination to overcome fear—not just for personal protection, but to ensure the very survival of social and economic life.
