A pandemic is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. Widespread endemic diseases with a stable number of infected individuals such as recurrences of seasonal influenza are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.
Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them. The effectiveness of vaccination has been widely studied and verified. Vaccination is the most effective method of preventing infectious diseases; widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world. However, some diseases, such as measles outbreaks in America, have seen rising cases due to relatively low vaccination rates in the 2010s – attributed, in part, to vaccine hesitancy. According to the World Health Organization, vaccination prevents 3.5–5 million deaths per year.
The smallpox vaccine is the first vaccine to have been developed against a contagious disease. In 1796, British physician Edward Jenner demonstrated that an infection with the relatively mild cowpox virus conferred immunity against the deadly smallpox virus. Cowpox served as a natural vaccine until the modern smallpox vaccine emerged in the 20th century. From 1958 to 1977, the World Health Organization (WHO) conducted a global vaccination campaign that eradicated smallpox, making it the only human disease to be eradicated. Although routine smallpox vaccination is no longer performed on the general public, the vaccine is still being produced to guard against bioterrorism, biological warfare, and mpox.
The 1972 Yugoslav smallpox outbreak was the largest outbreak of smallpox in Europe after the Second World War. It was centered in SAP Kosovo, a province of Serbia within Yugoslavia, and the capital city of Belgrade. A Kosovar Albanian Muslim pilgrim had contracted the smallpox virus in the Middle East. Upon returning to his home in Kosovo, he started the epidemic in which 175 people were infected, killing 35. The epidemic was efficiently contained by enforced quarantine and mass vaccination. The 1982 film Variola Vera is based on the event.
Donald Ainslie Henderson was an American medical doctor, educator, and epidemiologist who directed a 10-year international effort (1967–1977) that eradicated smallpox throughout the world and launched international childhood vaccination programs. From 1977 to 1990, he was Dean of the Johns Hopkins School of Public Health. Later, he played a leading role in instigating national programs for public health preparedness and response following biological attacks and national disasters. At the time of his death, he was Professor and Dean Emeritus of the Johns Hopkins Bloomberg School of Public Health, and Professor of Medicine and Public Health at the University of Pittsburgh, as well as Distinguished Scholar at the UPMC Center for Health Security.
Vaccine hesitancy is a delay in acceptance, or refusal, of vaccines despite the availability of vaccine services and supporting evidence. The term covers refusals to vaccinate, delaying vaccines, accepting vaccines but remaining uncertain about their use, or using certain vaccines but not others. The scientific consensus that vaccines are generally safe and effective is overwhelming. Vaccine hesitancy often results in disease outbreaks and deaths from vaccine-preventable diseases. Therefore, the World Health Organization characterizes vaccine hesitancy as one of the top ten global health threats.
William Herbert Foege is an American physician and epidemiologist who is credited with "devising the global strategy that led to the eradication of smallpox in the late 1970s". From May 1977 to 1983, Foege served as the Director of the Centers for Disease Control and Prevention.
Ali Maow Maalin was a Somali hospital cook and health worker from Merca who is the last person known to have been infected with naturally occurring Variola minor smallpox. He was diagnosed with the disease in October 1977 and made a full recovery. Although he had many contacts, none of them developed the disease, and an aggressive containment campaign was successful in preventing an outbreak. Smallpox was declared to have been eradicated globally by the World Health Organization (WHO) two years later. Maalin was subsequently involved in the successful poliomyelitis eradication campaign in Somalia, and he died of malaria while carrying out polio vaccinations after the re-emergence of the poliovirus in 2013.
The Centers for Disease Control and Prevention, formed in 1946, is the leading national public health institute of the United States. It is a United States federal agency, under the United States Department of Health and Human Services. Its main goal is to protect public health and safety through the control and prevention of disease, injury, and disability in the US and internationally.
Polio eradication, the permanent global cessation of circulation of the poliovirus and hence elimination of the poliomyelitis (polio) it causes, is the aim of a multinational public health effort begun in 1988, led by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF) and the Rotary Foundation. These organizations, along with the U.S. Centers for Disease Control and Prevention (CDC) and The Gates Foundation, have spearheaded the campaign through the Global Polio Eradication Initiative (GPEI). Successful eradication of infectious diseases has been achieved twice before, with smallpox in humans and rinderpest in ruminants.
Mass vaccination is a public policy effort to vaccinate a large number of people, possibly the entire population of the world or of a country or region, within a short period of time. This policy may be directed during a pandemic, when there is a localized outbreak or scare of a disease for which a vaccine exists, or when a new vaccine is invented.
The eradication of infectious diseases is the reduction of the prevalence of an infectious disease in the global host population to zero.
Smallpox was an infectious disease caused by variola virus which belongs to the genus Orthopoxvirus. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization (WHO) certified the global eradication of the disease in 1980, making smallpox the only human disease to be eradicated.
The history of smallpox extends into pre-history. Genetic evidence suggests that the smallpox virus emerged 3,000 to 4,000 years ago. Prior to that, similar ancestral viruses circulated, but possibly only in other mammals, and possibly with different symptoms. Only a few written reports dating from about 500 AD to 1000 AD are considered reliable historical descriptions of smallpox, so understanding of the disease prior to that has relied on genetics and archaeology. However, during the 2nd millennium AD, especially starting in the 16th century, reliable written reports become more common. The earliest physical evidence of smallpox is found in the Egyptian mummies of people who died some 3,000 years ago. Smallpox has had a major impact on world history, not least because indigenous populations of regions where smallpox was non-native, such as the Americas and Australia, were rapidly and greatly reduced by smallpox during periods of initial foreign contact, which helped pave the way for conquest and colonization. During the 18th century the disease killed an estimated 400,000 Europeans each year, including five reigning monarchs, and was responsible for a third of all blindness. Between 20 and 60% of all those infected—and over 80% of infected children—died from the disease.
Pakistan is one of the two remaining countries in the world where poliomyelitis (polio) is still categorized as an endemic viral infection, the other one being Afghanistan. While it has yet to fully eradicate Polio, there has been a downwards trend in the number of reported cases per year; the total count of wild poliovirus cases in Pakistan in 2019 was 147, compared to 84 in 2020, 1 in 2021, and 20 in 2022. As of March 2023, there has been 1 documented case in Pakistan.
Ring vaccination is a strategy to inhibit the spread of a disease by vaccinating those who are most likely to be infected.
Vaccination policy of the United States is the subset of U.S. federal health policy that deals with immunization against infectious disease. It is decided at various levels of the government, including the individual states. This policy has been developed over the approximately two centuries since the invention of vaccination with the purpose of eradicating disease from the U.S. population, or creating a herd immunity. Policies intended to encourage vaccination impact numerous areas of law, including regulation of vaccine safety, funding of vaccination programs, vaccine mandates, adverse event reporting requirements, and compensation for injuries asserted to be associated with vaccination.
Alasdair Macintosh Geddes is Emeritus Professor of Infection at the University of Birmingham Medical School. In 1978, as the World Health Organization (WHO) was shortly to announce that the world's last case of smallpox had occurred a year earlier in Somalia, Geddes diagnosed a British woman with the disease in Birmingham, England. She was found to be the index case of the outbreak and became the world's last reported fatality due to the disease, five years after he had gained experience on the frontline of the WHO's smallpox eradication programme in Bangladesh in 1973.
John Michael Lane was an American epidemiologist who was a director of the Epidemic Intelligence Service's Global Smallpox Eradication program from 1973 to 1981, and who played a leading role in the eradication of smallpox in 1977.
Mahendra Dutta was an Indian public health official, best known for his efforts to eradicate smallpox in India as the appraisal officer for smallpox in Bihar during the 1974 epidemic. He later served as Health Commissioner of New Delhi, Chief Epidemiologist of the National Centre for Disease Control, and Deputy Director General of the Ministry of Health and Family Welfare's public health operations. Additionally, he was a founding member of the Indian Public Health Association, serving as its president in 1987. Dutta's career is featured in an episode of Céline Gounder's 2023 podcast series Epidemic: Eradicating Smallpox.
