What is COVID-19 and what causes it?

COVID-19 (Coronavirus Disease 2019) is caused by SARS-CoV-2, a novel betacoronavirus that emerged in late 2019. It is transmitted primarily through respiratory droplets and aerosols, particularly in enclosed, poorly ventilated spaces. The clinical spectrum ranges from asymptomatic infection to mild respiratory illness, severe pneumonia requiring intensive care, and death. Older adults and those with underlying health conditions face the highest risk of severe disease.

How many people died from COVID-19?

Over 7 million deaths were officially reported to WHO, but the true toll is far higher. WHO's excess mortality estimates — comparing deaths during the pandemic to expected deaths based on prior trends — suggest global excess mortality of approximately 15 million in 2020-2021 alone. The gap between reported and excess deaths reflects both direct COVID-19 deaths and indirect deaths from disrupted health services.

Long COVID (Post-COVID-19 condition) is defined by WHO as symptoms continuing or developing beyond 3 months after initial SARS-CoV-2 infection, lasting at least 2 months, not explained by another diagnosis. WHO estimates hundreds of millions of cases globally. The most common features are fatigue, cognitive impairment ("brain fog"), breathlessness, and post-exertional malaise. The biological mechanisms include immune dysregulation, microbiome disruption, and viral persistence.

How effective were COVID-19 vaccines?

Highly effective. A landmark analysis (Watson et al., Lancet Infectious Diseases 2022) estimated that 14.4 million deaths were averted by COVID-19 vaccines in their first year of use (December 2020-December 2021). The mRNA vaccines (BNT162b2/Comirnaty, mRNA-1273/Spikevax) demonstrated 90%+ efficacy against severe disease and death in the pivotal trials and remained highly effective against hospitalisation and death with subsequent variants.

What is the WHO Pandemic Agreement?

The WHO Pandemic Agreement, adopted by the 78th World Health Assembly in May 2025, is the first international treaty specifically targeting pandemic prevention, preparedness and response. Its key provisions cover: pathogen access and benefit-sharing (PABS) system; equitable access to pandemic countermeasures; One Health approaches; supply chain and logistics; financing; and the Intergovernmental Working Group for implementation. It was two years in negotiation.

How has COVID-19 affected other health programmes?

COVID-19 set back progress on virtually every other health goal. TB services were severely disrupted (1.4 million fewer people treated in 2020). Routine childhood vaccinations dropped — 25 million children under-vaccinated in 2021. Maternal mortality increased in some settings. HIV testing and treatment were interrupted. The indirect health impact of the pandemic may ultimately exceed the direct COVID-19 death toll in some regions.

What are the COVID-19 variants and why do they matter?

SARS-CoV-2 evolves through mutation, occasionally producing variants with increased transmissibility, immune evasion or virulence. WHO classifies variants into Variants of Concern (VOC — Alpha, Beta, Gamma, Delta, Omicron) and lower-tier categories. Omicron's emergence in late 2021 demonstrated the importance of global variant surveillance: it spread faster than any predecessor, partially evaded vaccine immunity, but generally caused less severe disease. Continued surveillance through WHO's SARS-CoV-2 Evolution Working Group is essential.

What antivirals exist for COVID-19?

Oral antivirals approved for COVID-19 include: nirmatrelvir/ritonavir (Paxlovid, Pfizer) — a protease inhibitor combination highly effective at reducing hospitalisation and death when given within 5 days of symptom onset; molnupiravir (Lagevrio, Merck) — a nucleoside analogue with more modest efficacy; and remdesivir (intravenous) for hospitalised patients. Access to these treatments in LMICs remains severely limited, replicating the vaccine access inequities of 2021.

What is the COVID-19 equity problem?

Vaccine inequity was one of the most prominent failures of the COVID-19 response. By mid-2022, over 70% of people in high-income countries had received at least one vaccine dose, while many low-income countries remained below 20%. The COVAX facility — designed to ensure equitable global access — was underfinanced and outcompeted by bilateral deals. This inequity cost lives, prolonged the pandemic and enabled variant emergence in under-vaccinated populations.

How did COVID-19 change the global health system?

COVID-19 accelerated multiple health system changes: mRNA vaccine technology proved scalable and adaptable; digital health tools (telemedicine, remote monitoring, digital contact tracing) expanded rapidly; the pandemic exposed chronic underinvestment in public health infrastructure; and it catalysed the WHO Pandemic Agreement negotiations. It also demonstrated both the capabilities and the profound limitations of the International Health Regulations as they existed before 2025.

What is One Health and how does it relate to COVID-19?

One Health is an integrated approach recognising that human, animal and environmental health are interconnected. COVID-19 is a zoonotic disease — it crossed from animals to humans — making One Health directly relevant to pandemic prevention. The WHO Pandemic Agreement includes One Health provisions: monitoring animal-human interfaces, improving zoonotic disease surveillance and strengthening the intersection of ecological, agricultural and public health systems.

How does GMJ News cover COVID-19?

GMJ News tracks ongoing COVID-19 developments — variant surveillance, antiviral approvals, long COVID research, Pandemic Agreement implementation — as well as the pandemic's continuing impact on other health programmes. Georgia's experience of COVID-19, including health system strain and vaccination programme rollout, is a subject of ongoing coverage in the Georgian Medical Journal.

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COVID-19

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

COVID-19 has caused over 7 million reported deaths — with WHO-estimated excess mortality far higher — and remains a circulating global pathogen even after the Public Health Emergency of International Concern ended in May 2023. Vaccination changed history: an estimated 14.4 million deaths were averted by COVID-19 vaccines in their first year alone (Lancet Infectious Diseases 2022). The unresolved burdens are long COVID, affecting a meaningful share of those infected, and preparedness itself — the WHO Pandemic Agreement adopted by the World Health Assembly in 2025 is the world's attempt to ensure the next pandemic is met with equity and speed rather than improvisation.

Key messages

Historic pandemic

COVID-19 caused over 7 million reported deaths and WHO-estimated excess mortality far exceeding that figure. The Public Health Emergency of International Concern ended in May 2023 — but SARS-CoV-2 continues to circulate.

Vaccines changed history

An estimated 14.4 million deaths were averted by COVID-19 vaccines in their first year alone (Lancet ID 2022). The mRNA vaccine development marked a technological turning point in vaccinology.

Long COVID

Long COVID — persistent symptoms lasting beyond 12 weeks of infection — affects a meaningful share of those infected. WHO estimates hundreds of millions of cases globally, with fatigue, cognitive impairment and breathlessness as the most common features.

Pandemic Agreement

The WHO Pandemic Agreement, adopted by the World Health Assembly in May 2025, is the world's first international treaty specifically addressing pandemic prevention, preparedness and response.

Systems lesson

COVID-19 exposed profound inequities in health system resilience, vaccine access and pandemic governance. The pandemic simultaneously set back progress on all other major health goals — TB, HIV, routine immunisation, maternal health.

Ongoing evolution

SARS-CoV-2 continues to evolve. Variant surveillance, updated vaccines, antivirals (nirmatrelvir/ritonavir, molnupiravir) and maintaining preparedness systems remain global health priorities.

Key statistics

7M+

reported COVID deaths

WHO

14.4M

deaths averted by vaccines yr 1

Lancet ID 2022

100M+

estimated long COVID cases

WHO

2025

WHO Pandemic Agreement adopted

WHA78

May 2023

PHEIC ended

WHO

200+

countries and territories affected

WHO

Weekly COVID-19 deaths globally (thousands) 2020-2023 — WHO

Source: WHO COVID-19 dashboard. Reported deaths; true excess mortality substantially higher.

Glossary of key terms

SARS-CoV-2
WHO/ICTVSevere Acute Respiratory Syndrome Coronavirus 2 — the novel coronavirus causing COVID-19. A betacoronavirus that emerged in late 2019 and spread globally. Transmitted primarily through respiratory droplets and aerosols.

COVID-19
WHOCoronavirus Disease 2019 — the disease caused by SARS-CoV-2. Clinical spectrum ranges from asymptomatic to mild respiratory illness to severe pneumonia, organ failure and death.

Long COVID
WHOPost-COVID-19 condition: symptoms continuing or developing beyond 3 months after initial SARS-CoV-2 infection, lasting at least 2 months, not explained by another diagnosis. Common features: fatigue, cognitive impairment ("brain fog"), breathlessness, post-exertional malaise.

PHEIC
IHR/WHOPublic Health Emergency of International Concern — the highest alert level under the International Health Regulations (IHR 2005). COVID-19 was declared a PHEIC in January 2020 and this status ended in May 2023.

mRNA vaccine
FDA/EMAA vaccine using messenger RNA to instruct cells to produce the SARS-CoV-2 spike protein, triggering an immune response. The COVID-19 pandemic was the first large-scale deployment of mRNA vaccine technology, demonstrating its speed, safety and efficacy.

Pandemic Agreement
WHOThe WHO Pandemic Agreement, adopted by the 78th World Health Assembly (May 2025) — the first international treaty specifically addressing pandemic prevention, preparedness and response. Covers equitable access to countermeasures, surveillance, One Health and financing.