The idea of global pandemic It has been seared into our memories after COVID-19. What once sounded like something distant or from a history book suddenly became our daily life: masks, saturated ICUs, online classes, empty streets and headlines with figures of infections and deaths.
Beyond the emotional impact, COVID-19 has been a health and social crisis of colossal dimensions: hundreds of millions of confirmed cases, millions of deaths, an unprecedented scientific race to develop vaccines and treatments, patent debates, soaring gender inequalities, and a global economy in shock. And yet, it hasn't been the first major pandemic in history… nor will it be the last.
COVID-19 pandemic: what it was, when it started and where we are now
The call COVID-19 pandemic (or coronavirus pandemic) was caused by the SARS-CoV-2 virus. The first known cases appeared in December 2019 in Wuhan, in China's Hubei province, where a cluster of patients with pneumonia of unknown origin was reported, many of them linked to the Huanan Seafood Wholesale Market.
On January 30, 2020, the World Health Organization (WHO) declared the situation as public health emergency of international concernOn March 11, 2020, with thousands of cases detected in more than 100 countries, the WHO officially declared the situation a pandemic. This emergency remained in effect until May 5, 2023, when the international state of alert was lifted, although the virus continued to circulate.
By August 2023, more than 692 million confirmed cases and more than 7 million deaths officially attributed to COVID-19, with the virus circulating in some 260 countries and territories. Taking into account underreporting, it is estimated that at least 10% of the world's population was infected in the first few years, which translates to figures close to 780 million people infected in that initial phase alone.
Over time, the circulation of the virus has stabilized, and today many experts and governments speak of endemic phaseSARS-CoV-2 is still present, but without the explosive, global spikes of the early years, and with a large part of the population vaccinated or previously infected. Even so, as of October 27, 2024, COVID-19 had accumulated more than 7,07 million confirmed deaths and is now considered the fifth deadliest pandemic or epidemic on record.
From SARS-CoV-2 to COVID-19: virus, disease and names
The agent responsible for the pandemic is the SARS‑CoV‑2, a positive-sense single-stranded RNA coronavirus belonging to the Orthocoronavirinae subgroup. It is a zoonotic virus: it likely jumped from bats to humans, either directly or through an intermediate host. Its genome encodes several structural proteins, including the S (spike) protein, responsible for binding to the ACE2 cell receptor and initiating entry into the cell.
Initially, the disease was informally called "Wuhan pneumonia." The WHO provisionally used expressions such as acute respiratory illness due to 2019-nCoVOn February 11, 2020, the official name COVID-19 was established, an acronym for corona virus disease 2019In Spanish, both the RAE and Fundéu recommend the feminine form (COVID-19because the core is “disease”), although in everyday use the masculine “el covid” has also become established.
From a medical point of view, the COVID-19 It is a SARS-CoV-2 infection that can range from asymptomatic cases to severe pneumonia, acute respiratory distress syndrome, sepsis, and multiple organ failure. The case fatality rate estimated by the WHO in 2020 was around 0,5-1%, but with enormous differences depending on age, comorbidities, access to the healthcare system, and the stage of the pandemic.
How is SARS-CoV-2 transmitted and what are its symptoms?
SARS-CoV-2 is mainly transmitted from person to person through the airThese are respiratory droplets and aerosols that we emit when we talk, breathe, cough, sneeze, shout, or sing. These microdroplets can be inhaled directly at close range or remain suspended in the air in poorly ventilated, enclosed spaces.
There is also contagion through indirect contactThe droplets fall onto surfaces, the person touches that surface, and then touches their eyes, nose, or mouth. However, over time it was found that fomites (contaminated surfaces) played a lesser role in transmission compared to airborne transmission. Even so, the virus can remain on materials such as [unspecified] for hours or days. plastic, steel, cardboard, banknotes or glass, depending on the temperature and humidity.
The incubation period is usually around 5 dayswith a range of 2 to 14 days. There is evidence of transmission one or two days before the onset of symptoms, coinciding with the peak viral load. This greatly complicated control in the first phase, because apparently healthy people could actively transmit the virus.
The most common symptoms include fever, dry cough, fatigue, and difficulty breathingIn a large Chinese cohort of approximately 56,000 confirmed cases, 87,9% presented with fever, 67,7% with a dry cough, 38,1% with fatigue, and about 19% with dyspnea. Myalgia, headache, sore throat, diarrhea, nasal congestion, and, very strikingly at first, sudden weight loss were also described. smell and taste in a large proportion of patients.
In severe cases, bilateral pneumonia, acute respiratory distress syndrome, shock (often septic), thromboembolic events (deep vein thrombosis, pulmonary embolism, stroke), as well as renal and cardiac complications may occur. Lymphopenia, elevated inflammatory markers, and other phenomena were frequently described in intensive care units. cytokine stormThat is, an uncontrolled inflammatory response that damages the tissues themselves.
Cases, deaths, and differences between countries and population groups
The global figures are staggering: as of November 2023, there was talk of almost 700 million confirmed cases and nearly 7 million reported deaths. But from the beginning there was a serious problem: diagnostic capacity, case definition, and criteria for counting deaths varied greatly between countries.
In the first few months, countries like South Korea carried out mass screeningsreaching 10,000 PCR tests per day in early March 2020, which allowed for the detection of many mild cases and more realistic and lower case fatality rates. At the opposite extreme, Japan, the United Kingdom, and the United States initially conducted few tests, and Spain and Italy were also limited by a lack of reagents and equipped laboratories.
This meant that the actual number of infected people was much higher than the officially recorded figure. In Spain, at the end of March 2020, it was estimated that there could have been between 300,000 and 900,000 actual cases compared to the 39,000 detected. In China, asymptomatic cases that tested positive were not initially reported as confirmed, which also underestimated the true scale of the outbreak.
At the other extreme, when PCR capacity was greatly expanded, it was suggested that there could be overestimation of active cases, because the tests detected fragments of non-viable viral RNA weeks after the infection had passed. Something similar happened with the death toll: Italy, for example, only counted those who had tested positive as COVID-19 deaths, leaving out many elderly people who died in nursing homes without being tested. Belgium, on the other hand, included in its probable mortality statistics those who died in nursing homes with compatible symptoms even if they had not been tested.
In Spain it was found that supermortality The total number of deaths exceeding expectations during the epidemic waves was between 50% and 70% higher than the deaths officially attributed to COVID-19 by PCR testing, which gives an idea of the true impact. And if we look at it by groups, age is the key factor: the median age of those who died in Italy was around 79, and almost all of them had pre-existing conditions (hypertension, diabetes, heart disease, COPD, cancer, etc.).
Inequalities based on sex, gender and vulnerable groups
Although the virus can infect anyone, the data showed early on great inequalities by sex and genderIn many countries, mortality was higher in men than in women (for example, 4,7% versus 2,8% in China). Biological causes (hormonal differences, immune response, higher prevalence of smoking and chronic diseases in men) and behavioral factors have been identified.
However, when looking beyond the risk of death, women have suffered a much heavier impact On other fronts, in the labor market, caregiving responsibilities, working from home with children, the informal economy, and gender-based violence, the pandemic has increased the extreme inequalities women already exist. On average, women perform many more hours of unpaid domestic and care work, and in sectors such as healthcare they represent the majority of nursing and auxiliary staff, so their exposure to the virus was greater.
In Spain, for example, nearly 75% of infected healthcare workers were ofAdded to this are domestic and care workers, many in the informal economy, who lost their jobs during lockdowns and, because they did not contribute to social security, were excluded from state aid. In Latin America and the Caribbean, around half of those working without contracts are women, who represent a significant portion of the unpaid care sector.
The call “shadow pandemic” This refers to the dramatic increase in gender-based violence during lockdowns. School closures, job losses, and being confined with the abuser led to a surge in calls to helplines, domestic violence cases, and the demand for shelters, to the point of overwhelming these services. Less than 40% of victims seek formal help, and only 10% report the abuse to the police, further contributing to its invisibility.
The LGBTI community was also particularly hard hit: loss of income In already precarious sectors, there has been a closure of safe spaces for socialization, an increase in domestic violence for people who had to return to non-accepting homes, and the pandemic has been used as a political pretext in some countries to demonize sexual minorities or delay legal advances in rights.
Other health effects: beyond the virus
The massive attention to COVID-19 also had Collateral damage serious complications with other diseases. Many prevention, screening, and treatment programs were interrupted or reduced, and diagnoses of cancer, heart disease, chronic infections, and other illnesses were delayed. The WHO estimates, for example, that in 2020 approximately 500,000 additional people died from tuberculosis due to disruptions in detection and treatment.
Paradoxically, there was a historic drop in other respiratory infections such as seasonal flu and respiratory syncytial virus, especially in the Southern Hemisphere winter of 2020. It is likely that reduced international mobility, mask use, school closures, and social distancing cut the transmission of these viruses very effectively.
For healthcare workers, the pandemic meant a unprecedented stressIn countries like Spain, Intensive Care Units tripled their critical care bed capacity, improvising ICUs in operating rooms, recovery rooms, and other areas. Old ventilators and anesthesia equipment were reused, and emergency solutions were even devised in response to the global shortage of ventilators and protective equipment.
In addition to physical exhaustion, many professionals suffered moral distress This was due to having to prioritize scarce resources (ICU beds, ventilators, sedatives) and working with insufficient protective equipment at times. It is no coincidence that a very high proportion of healthcare workers became infected: in Spain, figures close to 14% of total cases were reported at certain points.
Diagnostic tests, serology and asymptomatic cases
To confirm active infection, the gold standard tool has been the PCR testsThese tests detect fragments of viral RNA. They are very sensitive, but this has two important implications: they allow the virus to be detected even with very low viral loads, and they can continue to give a positive result when the person is no longer contagious because only remnants of non-viable RNA remain.
At the same time, many countries carried out serological studies with antibody tests to estimate what percentage of the population had been infected in the preceding months, even if they no longer had detectable virus. Some illustrative results: in the Italian province of Bergamo, seroprevalence reached 57%, in Geneva it was around 11%, in Spain close to 10% in December 2020, and in New York City it exceeded 22% after the first wave.
This data confirmed that the The actual infection was far superior. The true number of cases was higher than that reflected in the reported figures, due to the large number of mild and asymptomatic cases and the limitations of initial testing. Furthermore, the data showed significant geographical differences depending on the intensity of the waves and the measures taken.
Prevention measures: from hand washing to confinement
The basic recommendations for slowing transmission have revolved around three main areas: hygiene, masks and distanceWashing hands with soap and water for at least 20 seconds, using hand sanitizer if that's not possible, avoiding touching your face with dirty hands, covering your mouth and nose when coughing or sneezing (ideally with the inside of your elbow), and ventilating spaces became everyday gestures.
The use of masks This has been one of the most visible debates. Initially, the WHO recommended masks for the general population, but with evidence of presymptomatic and aerosol transmission, many countries began recommending or mandating them indoors and in high-risk situations. Surgical and cloth masks reduce the emission of droplets into the environment, while N95/FFP2 respirators also offer protection to the wearer.
One little-discussed detail is that many masks and respirators are designed according to male facial patternsThis makes them fit worse for women and increases the risk of leaks. Furthermore, models with an exhalation valve are not suitable for pandemic control: they make breathing easier for the user, but expel unfiltered air, which, if the user is infected, can spread the virus.
In addition to individual measures, governments implemented strategies of proactivity in risk management y social distancing and reduced mobility: border closures, travel restrictions, capacity limits, suspension of mass events, closure of schools and universities, teleworking and, in many cases, strict home confinement.
These restrictions drastically reduced the basic reproduction number (R0). In Spain, for example, it is estimated to have fallen from values above 2 before the state of emergency to around 0,98 in April 2020, with a drop in the infection growth rate from 40% to approximately 3%. However, the economic and psychological cost was enormous: a collapse in activity, increased unemployment, and deterioration of mental health in a large part of the population, with a greater impact on young people, women and vulnerable groups.
Vaccines, patents and global inequality
The development of vaccines against COVID-19 was extraordinarily fastIn less than a year since the virus was sequenced, several vaccines had already been authorized: messenger RNA (Pfizer-BioNTech, Moderna), viral vector (AstraZeneca, Janssen, Sputnik V), inactivated virus (Sinopharm, Sinovac) and protein subunit vaccines, among others.
These vaccines differ in their technology and in the Cold chain Necessary: messenger RNA vaccines require freezing at -20 °C (Moderna) or even around -70 °C (Pfizer) for long-term storage, while many adenovirus or inactivated virus vaccines are stored under standard refrigeration. This logistical requirement complicated their distribution in countries with fragile infrastructure.
By early 2022, more than 9.37 billion dosesThis represented approximately 59% of the world's population with at least one dose at that time. By January 2023, the cumulative number of people vaccinated with at least one dose was around 5.294 billion, nearly two-thirds of the global population.
However, the distribution was very uneven. High-income countries, representing about 14% of the world's population, came to control nearly a half of the pre-purchased doses (more than 10 billion reserved in advance in December 2020). India and South Africa led a proposal at the WTO to temporarily suspend patents on vaccines, medicines, and technologies related to COVID-19 for the duration of the pandemic, with the support of more than 000 countries and numerous NGOs.
Most wealthy nations—including several European Union countries, the United States (initially), the United Kingdom, and Brazil—initially opposed the measure, defending the intellectual property framework. In May 2021, the United States surprised many by supporting a limited exemption focused on vaccines, but negotiations dragged on and the outcome was rather weak.
Vaccines were not only a health tool, but also a gigantic businessThe Pfizer-BioNTech vaccine broke sales records, generating nearly €70 billion between 2021 and 2022, while Moderna earned over €34 billion from its vaccines during the same period. At the same time, a surplus of doses emerged starting in late 2022, and disputes arose over the disposal of near-expiration batches.
Immunity, reinfections, and long COVID
Following infection, the body generates a immune response by combining antibodies and memory T and B cells. Several studies have shown that, in most people, having had COVID-19 significantly reduces the risk of reinfection in the following months and, if it does occur, makes the illness milder and less likely to require hospitalization.
For example, analyses conducted in 2021 suggested that those who had already recovered from the infection had approximately a 80% less risk of being reinfected for at least six months, and up to 94% less likely to develop symptoms, with confirmed reinfection rates around 0,6%. Subsequent research suggests that natural immunity, combined with or without vaccines, can be long-lasting thanks to memory B cells and long-lived plasma cells in bone marrow.
At the same time, the so-called Persistent COVID or “long COVID”: a set of symptoms that persist or appear weeks or months after the acute infection (fatigue, shortness of breath, brain fog, muscle pain, sleep disorders, alterations in taste or smell, etc.). This syndrome is more common in women and in people who had moderate or severe initial cases, but it can also affect previously healthy young people.
Neither previous infection nor vaccination guarantees absolute protection against new infections; what they do is reduce the likelihood of severe illness and deathTherefore, although many restrictions have been lifted, authorities recommend maintaining special caution in high-risk environments, protecting vulnerable people, and updating booster doses in high-risk groups (the elderly, immunocompromised, and people with serious comorbidities).
Treatments and therapies in development
During the first few months, the treatment of COVID-19 was mostly of supportOxygen, non-invasive or invasive ventilation, fever control, management of complications, and thrombosis prophylaxis were administered. Numerous drugs (hydroxychloroquine, lopinavir/ritonavir, interferons, colchicine, ivermectin, etc.) were tested, with results that were often disappointing or even harmful.
Over time, some have become more established useful therapies In specific contexts: systemic corticosteroids (such as dexamethasone) in patients with lung involvement and need for oxygen, certain antivirals such as remdesivir in early stages in people at risk, combinations such as nirmatrelvir/ritonavir (Paxlovid) orally, and the use of monoclonal antibodies against specific variants, although many lost effectiveness as the virus mutated.
Another approach has been the use of convalescent plasma (plasma from recovered individuals with high antibody titers) in very early stages, with some studies showing a reduction in progression to severe disease if administered early in specific groups. At a more experimental level, targets such as IL-6 (tocilizumab) have been explored in cases of cytokine storm, and in extreme cases, lung transplants have been performed in patients with irreversible lung destruction after severe COVID.
The investigation continues: testing is ongoing new antivirals, immune modulators and combinations of therapies, and the medium and long-term consequences, both organic and neuropsychiatric, are studied in more depth.
Socioeconomic and media dimension of a global pandemic
Beyond medicine, COVID-19 has been a socio-economic and political crisis on a global scale. Business closures, supply chain disruptions, the collapse of tourism, the explosion of remote work, forced online education, and much more have reshaped daily life and accelerated trends that were already underway, affecting the international trade trends.
Nearly a third of the world's population came to be confined Sometime in 2020, with severe restrictions on freedom of movement, economic activity was drastically reduced and unemployment skyrocketed, although it also led to a temporary drop in polluting emissions and pollution in many large cities.
At the same time, a veritable infodemic, information crisisA deluge of information, hoaxes, and conspiracy theories about the origin of the virus, vaccines, miracle cures, and so on. Social media, state media, and geopolitical actors used the pandemic to contest narratives, project soft power, and, in some cases, conceal management errors. There were cross-accusations of manipulating figures, cover-ups, propaganda, and coordinated disinformation campaigns.
China, for example, was criticized for delays in sharing complete data at the beginning, doubts about the true number of cases and deaths, and for using the shipment of medical supplies and vaccines to other countries as influence toolMeanwhile, high-ranking Western officials and media outlets were accused of exploiting the pandemic for geopolitical purposes, either to target the Chinese government or to challenge the narrative about the effectiveness of authoritarian systems compared to liberal democracies.
In this context, the WHO came under intense scrutiny: it was accused of both excessive deference to China and of being slow or ambiguous in some recommendations, and the influence of political interests on its decisions was questioned. At the same time, its role in coordinating scientific information, technical recommendations, and vaccination efforts has been crucial despite its limitations.
Pandemics in history: comparing to better understand
COVID-19 is not an isolated phenomenon: it is part of a long list of historical pandemics that have marked humanity. Among the best known are the Plague of Justinian (6th century) and the medieval Black Death, both caused by Yersinia pestis, which claimed tens of millions of lives; the successive cholera pandemics in the 19th and 20th centuries; the 1918 flu (misnamed Spanish flu), with an estimated 50 million deaths; the much milder 2009-2010 H1N1 flu pandemic; or HIV/AIDS, which remains an active pandemic with tens of millions of accumulated deaths.
Authors such as Robin Marantz Henig (A Dancing Matrix), Laurie Garrett (The Coming Plague) or Richard Preston (The Hot ZoneThey had been warning for decades that the combination of globalization, environmental destruction, urbanization and intensive contact with wildlife would make the emergence of new agents capable of triggering devastating pandemics increasingly likely.
In 2015, the TED Talk by Bill Gates The report on the lack of global preparedness for a major pandemic went viral years later as if it were a fulfilled prophecy: it clearly explained that the world invested enormous resources in military defense, but very little in alert systems, research and response capacity to emerging pathogens.
Looking at the succession of major epidemic crises, one gets the impression that there is “a pandemic every hundred years”Medical literature qualifies this perception: major pandemics are more frequent than they seem (SARS, MERS, avian flu, swine flu, Ebola…), and climate change, loss of biodiversity and high population density in megacities increase the risk of their emergence and spread.
In this context, COVID-19 has been a dress rehearsal, terrible but illustrative, of what it means to manage a pandemic in a hyperconnected world: from the crucial but imperfect role of organizations like the WHO to the need to strengthen public health, science, international cooperation and social safety nets. What we have experienced makes it clear that the question is not whether there will be another global pandemic, but when and how prepared we will be next time.
Everything that has happened with COVID-19—from the SARS-CoV-2 outbreak in Wuhan to the current endemic phase, including the brutal figures of infections and deaths, the race for vaccines, the healthcare system collapses, the increase in gender-based violence, the gap between rich and poor countries, and the disinformation campaigns—paints a very clear picture of what a global pandemic In the 21st century: a biological phenomenon with far-reaching political, economic, and social consequences that forces us to rethink how we live, how we care for ourselves, and what place collective health occupies on the global agenda, including the Sustainable Development Goals.
