Vaccine description | |
---|---|
Target | Yellow fever |
Vaccine type | Attenuated |
Clinical data | |
Trade names | YF-Vax, Stamaril |
Other names | 17D vaccine |
AHFS/Drugs.com | Monograph |
MedlinePlus | a607030 |
Pregnancy category |
|
Routes of administration | Subcutaneous |
ATC code | |
Legal status | |
Legal status | |
Identifiers | |
ChemSpider |
|
UNII | |
(what is this?) (verify) |
Yellow fever vaccine is a vaccine that protects against yellow fever. [4] Yellow fever is a viral infection that occurs in Africa and South America. [4] Most people begin to develop immunity within ten days of vaccination and 99% are protected within one month, and this appears to be lifelong. [4] The vaccine can be used to control outbreaks of disease. [4] It is given either by injection into a muscle or just under the skin. [4] [5]
The World Health Organization (WHO) recommends routine immunization in all countries where the disease is common. [4] This should typically occur between nine and twelve months of age. [4] Those traveling to areas where the disease occurs should also be immunized. [4] Additional doses after the first are generally not needed. [6]
The yellow fever vaccine is generally safe. [4] This includes in those with HIV infection but without symptoms. [4] Mild side effects may include headache, muscle pains, pain at the injection site, fever, and rash. [4] Severe allergies occur in about eight per million doses, serious neurological problems occur in about four per million doses, and organ failure occurs in about three per million doses. [4] It appears to be safe in pregnancy and is therefore recommended among those who will be potentially exposed. [4] It should not be given to those with very poor immune function. [7]
Yellow fever vaccine came into use in 1938. [8] It is on the World Health Organization's List of Essential Medicines. [9] [10] The vaccine is made from weakened yellow fever virus. [4] Some countries require a yellow fever vaccination certificate before entry from a country where the disease is common. [4] [5]
Medical experts recommend vaccinating people most at risk of contracting the virus, such as woodcutters working in tropical areas. [11] Insecticides, protective clothing, and screening of houses are helpful, but not always sufficient for mosquito control; medical experts recommend using personal insecticide spray in endemic areas. [12] In affected areas, mosquito control methods have proven effective in decreasing the number of cases. [13]
Travellers need to have the vaccine ten days prior to being in an endemic area in order to assure full immunity. [14] : 45
For most people, the vaccine remains effective permanently. People who are HIV positive at vaccination can benefit from a booster after ten years. [15]
On 17 May 2013, the World Health Organization (WHO) Strategic Advisory Group of Experts on immunization (SAGE) announced that a booster dose of yellow fever (YF) vaccine, ten years after a primary dose, is not necessary. [16] Since yellow fever vaccination began in the 1930s, only 12 known cases of yellow fever post-vaccination have been identified, after 600 million doses have been dispensed. [17] Evidence showed that among this small number of "vaccine failures", all cases developed the disease within five years of vaccination. [18] This demonstrates that immunity does not decrease with time. [19]
The World Health Organization recommends the vaccine between the ages of 9 and 12 months in areas where the disease is common. [4] Anyone over the age of nine months who has not been previously immunized and either lives in or is traveling to an area where the disease occurs should also be immunized. [4]
The yellow fever 17D vaccine is considered safe, with over 500 million doses given and very few documented cases of vaccine associated illness (62 confirmed cases and 35 deaths as of January 2019). [20] In no case of vaccine-related illness has there been evidence of the virus reverting to a virulent phenotype.[ medical citation needed ] [21]
The majority of adverse reactions to the 17D vaccine result from allergic reaction to the eggs in which the vaccine is grown. [22] Persons with known egg allergy should discuss this with their physician prior to vaccination. [23] In addition, there is a small risk of neurologic disease and encephalitis, particularly in individuals with compromised immune systems and very young children. The 17D vaccine is contraindicated in (among others) infants between zero and six months, [24] people with thymus disorders associated with abnormal immune cell function, people with primary immunodeficiencies, and anyone with a diminished immune capacity including those taking immunosuppressant drugs. [25]
There is a small risk of more severe yellow fever-like disease associated with the vaccine. This reaction, known as yellow fever vaccine-associated acute viscerotropic disease (YEL-AVD), [26] causes a fairly severe disease closely resembling yellow fever caused by virulent strains of the virus. [27] The risk factors for YEL-AVD are not known, although it has been suggested that it may be genetic. [28] The 2'-5'-oligoadenylate synthase (OAS) component of the innate immune response has been shown to be particularly important in protection from Flavivirus infection. [29] Another reaction to the yellow fever vaccine is known as yellow fever vaccine-associated acute neurotropic disease (YEL-AND). [30]
The Canadian Medical Association published a 2001 CMAJ article entitled "Yellow fever vaccination: be sure the patient needs it". [31] The article begins by stating that of the seven people who developed system failure within two to five days of the vaccine in 1996–2001, six died "including 2 who were vaccinated even though they were planning to travel to countries where yellow fever has never been reported." [32] The article cites that "3 demonstrated histopatholic changes consistent with wild yellow fever virus." [33] The author recommends vaccination for only non-contraindicated travelers (see the articles list) and those travelers going where yellow fever activity is reported or in the endemic zone which can be found mapped at the CDC website cited below. [34] In addition, the 2010 online edition of the Center for Disease Control Traveler's Health Yellow Book states that between 1970 and 2002 only "nine cases of yellow fever were reported in unvaccinated travelers from the United States and Europe who traveled" to West Africa and South America, and 8 of the 9 died. [35] However, it goes on to cite "only 1 documented case of yellow fever in a vaccinated traveler. [36] This nonfatal case occurred in a traveler from Spain who visited several West African countries in 1988". [37]
African tropical cultures had adopted burial traditions in which the deceased were buried near their habitation, including those who died of Yellow fever. [38] This ensured that people within these cultures gained immunity through a childhood case of "endemic" yellow fever through acquired immunity. This led to a lasting misperception, first by colonial authorities and foreign medical experts, that Africans have a "natural immunity" [39] to the illness. In the nineteenth century health provisioners forced abandonment of these traditional burial traditions, leading to local populations dying of yellow fever as frequently as those without such burial customs such as settler populations. [40]
The first modern attempts to develop a yellow fever vaccine followed the opening of the Panama Canal in 1912, which increased global exposure to the disease. [41] The Japanese bacteriologist Hideyo Noguchi led investigations for the Rockefeller Foundation in Ecuador that resulted in a vaccine based on his theory that the disease was caused by a leptospiral bacterium. [41] However, other investigators could not duplicate his results and the ineffective vaccine was eventually abandoned.[ citation needed ]
Another vaccine was developed from the "French strain" of the virus, obtained by Pasteur Institute scientists from a man in Dakar, Senegal, who survived his bout with the disease.[ citation needed ] This vaccine could be administered by scarification, like the smallpox vaccine, and was given in combination to produce immunity to both diseases, but it also had severe systemic and neurologic complications in a few cases. [42] Attempts to attenuate the virus used in the vaccine failed. Scientists at the Rockefeller Foundation developed another vaccine derived from the serum of an African named Asibi in 1927, the first isolation of the virus from a human. [43] It was safer but involved the use of large amounts of human serum, which limited widespread use. [44] Both vaccines were in use for several years, the Rockefeller vaccine in the Western hemisphere and England, and the Pasteur Institute vaccine in France and its African colonies. [45]
In 1937, Max Theiler, working with Hugh Smith and Eugen Haagen at the Rockefeller Foundation to improve the vaccine from the "Asibi" strain, discovered that a favorable chance mutation in the attenuated virus had produced a highly effective strain that was named 17D. [41] Following the work of Ernest Goodpasture, Theiler used chicken eggs to culture the virus. After field trials in Brazil, over one million people were vaccinated by 1939, without severe complications. [8] This vaccine was widely used by the U.S. Army during World War II. [46] For his work on the yellow fever vaccine, Theiler received the 1951 Nobel Prize in Physiology or Medicine. [47] Only the 17D vaccine remains in use today. [4]
Theiler's vaccine was responsible for the largest outbreak of hepatitis B in history, infecting 330,000 soldiers and giving 50,000 jaundice between 1941 and 1942. [48] At the time, chronic infectious hepatitis was not known, so when human serum was used in vaccine preparation, serum drawn from chronic hepatitis B virus (HBV) carriers contaminated the yellow fever vaccine. [49] In 1941, researchers at Rocky Mountain Laboratories developed a safer alternative, an "aqueous-base" version of the 17D vaccine using distilled water combined with the virus grown in chicken eggs. [50] Since 1971, screening technology for HBV has been available and is routinely used in situations where HBV contamination is possible including vaccine preparation. [51]
Also in the 1930s, a French team developed the French neurotropic vaccine (FNV), which was extracted from mouse brain tissue. [52] Since this vaccine was associated with a higher incidence of encephalitis, FNV was not recommended after 1961. Vaccine 17D is still in use, and more than 400 million doses have been distributed. Little research has been done to develop new vaccines. Newer vaccines, based on vero cells, are in development (as of 2018). [53] [54] [55]
Increases in cases of yellow fever in endemic areas of Africa and South America in the 1980s were addressed by the WHO Yellow Fever Initiative launched in the mid-2000s. [56] The initiative was supported by the Gavi Alliance, a collaboration of the WHO, UNICEF, vaccine manufacturers, and private philanthropists such as the Bill & Melinda Gates Foundation. [57] Gavi-supported vaccination campaigns since 2011 have covered 88 million people in 14 countries considered at "high-risk" of a yellow fever outbreak (Angola was considered "medium risk"). As of 2013, there were four WHO-qualified manufacturers: Bio-Manguinhos in Brazil (with the Oswaldo Cruz Foundation), Institute Pasteur in Dakar, Senegal, the Federal State Unitary Enterprise of Chumakov Institute in Russia, and Sanofi Pasteur, the French pharmaceutical company. [58] [59] Two other manufacturers supply domestic markets: Wuhan Institute of Biological Products in China and Sanofi Pasteur in the United States. [60]
Demand for yellow fever vaccine for preventive campaigns has increased from about five million doses per year to a projected 62 million per year by 2014. [61] UNICEF reported in 2013 that supplies were insufficient. Manufacturers are producing about 35 million of the 64 million doses needed per year. [62] Demand for the yellow fever vaccine has continued to increase due to the growing number of countries implementing yellow fever vaccination as part of their routine immunization programmes. [63]
The outbreak of yellow fever in Angola and in the Democratic Republic of Congo in 2016 has raised concerns about whether the global supply of vaccine is adequate to meet the need during a large epidemic or pandemic of the disease. [64] Routine childhood immunization was suspended in other African countries to ensure an adequate supply in the vaccination campaign against the outbreak in Angola. [65] Emergency stockpiles of vaccine diverted to Angola, which consisted of about 10 million doses at the end of March 2016, had become exhausted, [58] [66] but were being replenished by May 2016. [67] However, in August it was reported that about one million doses of six million shipped in February had been sent to the wrong place or not kept cold enough to ensure efficacy, resulting in shortages to fight the spreading epidemic in DR Congo. [68] As an emergency measure, experts suggested fractional dose vaccination, using a fractional dose (1/5 or 1/10 of the usual dose) to extend existing supplies of vaccine. [69] [65] Others have noted that switching manufacturing processes to modern cell-culture technology might improve vaccine supply shortfalls, [60] as the manufacture of the current vaccine in chicken eggs is slow and laborious. [70] On 17 June 2016, the WHO agreed to the use of 1/5 the usual dose as an emergency measure during the ongoing outbreak in Angola and the DR Congo. [63] [71] The fractional dose would not qualify for a yellow fever certificate of vaccination for travelers. Later studies found that the fractional dose was just as protective as the full dose, even 10 years after vaccination. [72]
As of February 2021, UNICEF reported awarded contract prices of ranging from US$ 0.97 to US$ 1.444 per dose under multi-year contracts with various suppliers. [73]
Travellers who wish to enter certain countries or territories must be vaccinated against yellow fever 10 days before crossing the border, and be able to present a vaccination record/certificate at the border checks. [14] : 45 In most cases, this travel requirement depends on whether the country they are travelling from has been designated by the World Health Organization as being a 'country with risk of yellow fever transmission'. [74] In a few countries, it does not matter which country the traveller comes from: everyone who wants to enter these countries must be vaccinated against yellow fever. [75] There are exemptions for newborn children; in most cases, any child who is at least 9 months or 1 year old needs to be vaccinated. [76]
Yellow fever vaccination requirements for international travel (January 2023) [76] | |||
---|---|---|---|
Country or territory | Status | Vaccination required for travellers coming from | Traveller age |
Albania | No risk | Risk countries | 1 year or older |
Algeria | No risk | Risk countries [note 4] | 1 year or older |
Angola | Risk country | All countries | 9 months or older |
Antigua and Barbuda | No risk | Risk countries | 1 year or older |
Argentina | Risk provinces: Misiones, Corrientes | No [note 3] | – |
Aruba | No risk | Risk countries [note 4] | 9 months or older |
Australia | No risk | Risk countries [note 4] | 1 year or older |
Bahamas | No risk | Risk countries [note 4] | 1 year or older |
Bahrain | No risk | Risk countries [note 4] | 9 months or older |
Bangladesh | No risk | Risk countries [note 5] | 1 year or older |
Barbados | No risk | Risk countries | 1 year or older |
Benin | Risk country | All countries | 1 year or older |
Bolivia | Risk country | Risk countries | 1 year or older |
Bonaire | No risk | Risk countries [note 4] | 9 months or older |
Botswana | No risk | Risk countries [note 5] | 1 year or older |
Brazil | Risk country | No [note 3] | – |
Brunei | No risk | Risk countries [note 4] | 9 months or older |
Burkina Faso | Risk country | All countries | 9 months or older |
Burundi | Risk country | All countries | 9 months or older |
Cabo Verde | No risk | Risk countries [note 4] | 1 year or older |
Cambodia | No risk | Risk countries [note 4] | 1 year or older |
Cameroon | Risk country | All countries | 9 months or older |
Central African Republic | Risk country | All countries | 9 months or older |
Chad | Risk country | Risk countries | 9 months or older |
China | No risk | Risk countries [note 5] | 9 months or older |
Christmas Island | No risk | Risk countries [note 4] | 1 year or older |
Colombia | Risk country | Risk countries [note 4] | 1 year or older |
Congo-Brazzaville | Risk country | All countries | 9 months or older |
Congo-Kinshasa | Risk country | All countries | 9 months or older |
Costa Rica | No risk | Risk countries | 9 months or older |
Côte d'Ivoire | Risk country | All countries | 9 months or older |
Cuba | No risk | Risk countries [note 4] | 9 months or older |
Curaçao | No risk | Risk countries [note 4] | 9 months or older |
Djibouti | No risk | Risk countries [note 4] | 1 year or older |
Dominica | No risk | Risk countries [note 4] | 1 year or older |
Dominican Republic | No risk | Risk countries [note 4] | 1 year or older |
Ecuador | Risk country | Risk countries [note 4] | 1 year or older |
Egypt | No risk | Risk countries [note 4] | 9 months or older |
El Salvador | No risk | Risk countries [note 4] | 1 year or older |
Equatorial Guinea | Risk country | Risk countries | 9 months or older |
Eritrea | No risk | Risk countries | 9 months or older |
Eswatini | No risk | Risk countries [note 5] | 9 months or older |
Ethiopia | Risk country | Risk countries [note 4] | 9 months or older |
Fiji | No risk | Risk countries [note 4] | 1 year or older |
French Guiana | Risk country | All countries | 1 year or older |
French Polynesia | No risk | Risk countries [note 4] | 9 months or older |
Gabon | Risk country | All countries | 1 year or older |
Gambia | Risk country | Risk countries | 9 months or older |
Ghana | Risk country | All countries | 9 months or older |
Grenada | No risk | Risk countries [note 4] | 1 year or older |
Guadeloupe | No risk | Risk countries [note 4] | 1 year or older |
Guatemala | No risk | Risk countries [note 4] | 1 year or older |
Guinea | Risk country | Risk countries | 9 months or older |
Guinea-Bissau | Risk country | All countries | 1 year or older |
Guyana | Risk country | Risk countries [note 5] | 1 year or older |
Haiti | No risk | Risk countries | 1 year or older |
Honduras | No risk | Risk countries [note 4] | 1 year or older |
India | No risk | Risk countries [note 5] | 9 months or older |
Indonesia | No risk | Risk countries | 9 months or older |
Iran | No risk | Risk countries [note 4] | 9 months or older |
Iraq | No risk | Risk countries [note 4] | 9 months or older |
Jamaica | No risk | Risk countries [note 4] | 1 year or older |
Jordan | No risk | Risk countries [note 4] | 1 year or older |
Kenya | Risk country | Risk countries | 1 year or older |
Liberia | Risk country | Risk countries | 9 months or older |
Libya | No risk | Risk countries | 1 year or older |
Madagascar | No risk | Risk countries [note 4] | 9 months or older |
Malawi | No risk | Risk countries [note 4] | 1 year or older |
Malaysia | No risk | Risk countries [note 4] | 1 year or older |
Maldives | No risk | Risk countries [note 4] | 9 months or older |
Mali | Risk country | All countries | 1 year or older |
Malta | No risk | Risk countries [note 4] | 9 months or older |
Martinique | No risk | Risk countries [note 4] | 1 year or older |
Mauritania | Risk country | Risk countries | 1 year or older |
Mayotte | No risk | Risk countries [note 4] | 1 year or older |
Montserrat | No risk | Risk countries [note 5] | 1 year or older |
Mozambique | No risk | Risk countries [note 4] | 9 months or older |
Myanmar | No risk | Risk countries [note 4] | 1 year or older |
Namibia | No risk | Risk countries [note 4] | 9 months or older |
Nepal | No risk | Risk countries [note 4] | 1 year or older |
New Caledonia | No risk | Risk countries [note 4] | 1 year or older |
Nicaragua | No risk | Risk countries | 1 year or older |
Niger | Risk country | All countries | 1 year or older |
Nigeria | Risk country | Risk countries [note 5] | 9 months or older |
Niue | No risk | Risk countries | 9 months or older |
North Korea | No risk | Risk countries | 1 year or older |
Oman | No risk | Risk countries [note 4] | 9 months or older |
Pakistan | No risk | Risk countries | 1 year or older |
Panama | Risk country | Risk countries [note 4] | 1 year or older |
Papua New Guinea | No risk | Risk countries [note 5] | 1 year or older |
Paraguay | Risk country | Risk countries | 1 year or older |
Peru | Risk country | No [note 3] | – |
Philippines | No risk | Risk countries [note 4] | 1 year or older |
Pitcairn Islands | No risk | Risk countries | 1 year or older |
Qatar | No risk | Risk countries | 9 month or older |
Rwanda | No risk | Risk countries | 1 year or older |
Saint Barthélemy | No risk | Risk countries [note 4] | 1 year or older |
Saint Helena | No risk | Risk countries | 1 year or older |
Saint Kitts and Nevis | No risk | Risk countries | 1 year or older |
Saint Lucia | No risk | Risk countries | 9 months or older |
Saint Martin | No risk | Risk countries [note 4] | 1 year or older |
Saint Vincent and the Grenadines | No risk | Risk countries | 1 year or older |
Samoa | No risk | Risk countries [note 4] | 1 year or older |
São Tomé and Príncipe | No risk | Risk countries [note 5] | 1 year or older |
Saudi Arabia | No risk | Risk countries [note 4] | 9 months or older |
Senegal | Risk country | Risk countries [note 5] | 9 months or older |
Seychelles | No risk | Risk countries [note 4] | 1 year or older |
Sierra Leone | Risk country | All countries | Unknown |
Singapore | No risk | Risk countries [note 4] | 1 year or older |
Sint Eustatius | No risk | Risk countries | 6 months or older |
Sint Maarten | No risk | Risk countries | 9 months or older |
Solomon Islands | No risk | Risk countries | 9 months or older |
South Africa | No risk | Risk countries [note 4] | 1 year or older |
South Sudan | Risk country | All countries | 9 months or older |
Sri Lanka | No risk | Risk countries [note 4] | 9 months or older |
Sudan | Risk provinces: South of Khartoum or Sahara Desert | No | – |
Suriname | Risk country | Risk countries [note 4] | 1 year or older |
Tanzania | No risk | Risk countries [note 4] | 1 year or older |
Thailand | No risk | Risk countries [note 4] | 9 month or older |
Togo | Risk country | All countries | 9 months or older |
Trinidad and Tobago | Risk region: Trinidad | Risk countries | 1 year or older |
Uganda | Risk country | All countries | 1 year or older |
United Arab Emirates | No risk | Risk countries [note 4] | 9 months or older |
Venezuela | Risk country | Risk countries [note 4] | 1 year or older |
Wallis and Futuna | No risk | Risk countries [note 4] | 1 year or older |
Zambia | No risk | Risk countries [note 4] | 1 year or older |
Zimbabwe | No risk | Risk countries [note 4] | 9 months or older |
|
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.
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious or malignant disease. The safety and effectiveness of vaccines has been widely studied and verified. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and recognize further and destroy any of the microorganisms associated with that agent that it may encounter in the future.
Yellow fever is a viral disease of typically short duration. In most cases, symptoms include fever, chills, loss of appetite, nausea, muscle pains—particularly in the back—and headaches. Symptoms typically improve within five days. In about 15% of people, within a day of improving the fever comes back, abdominal pain occurs, and liver damage begins causing yellow skin. If this occurs, the risk of bleeding and kidney problems is increased.
Measles is a highly contagious, vaccine-preventable infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than 40 °C (104 °F), cough, runny nose, and inflamed eyes. Small white spots known as Koplik's spots may form inside the mouth two or three days after the start of symptoms. A red, flat rash which usually starts on the face and then spreads to the rest of the body typically begins three to five days after the start of symptoms. Common complications include diarrhea, middle ear infection (7%), and pneumonia (6%). These occur in part due to measles-induced immunosuppression. Less commonly seizures, blindness, or inflammation of the brain may occur. Other names include morbilli, rubeola, red measles, and English measles. Both rubella, also known as German measles, and roseola are different diseases caused by unrelated viruses.
The MMR vaccine is a vaccine against measles, mumps, and rubella, abbreviated as MMR. The first dose is generally given to children around 9 months to 15 months of age, with a second dose at 15 months to 6 years of age, with at least four weeks between the doses. After two doses, 97% of people are protected against measles, 88% against mumps, and at least 97% against rubella. The vaccine is also recommended for those who do not have evidence of immunity, those with well-controlled HIV/AIDS, and within 72 hours of exposure to measles among those who are incompletely immunized. It is given by injection.
The DPT vaccine or DTP vaccine is a class of combination vaccines to protect against three infectious diseases in humans: diphtheria, pertussis, and tetanus (lockjaw). The vaccine components include diphtheria and tetanus toxoids, and either killed whole cells of the bacterium that causes pertussis or pertussis antigens. The term toxoid refers to vaccines which use an inactivated toxin produced by the pathogen which they are targeted against to generate an immune response. In this way, the toxoid vaccine generates an immune response which is targeted against the toxin which is produced by the pathogen and causes disease, rather than a vaccine which is targeted against the pathogen itself. The whole cells or antigens will be depicted as either "DTwP" or "DTaP", where the lower-case "w" indicates whole-cell inactivated pertussis and the lower-case "a" stands for "acellular". In comparison to alternative vaccine types, such as live attenuated vaccines, the DTP vaccine does not contain any live pathogen, but rather uses inactivated toxoid to generate an immune response; therefore, there is not a risk of use in populations that are immune compromised since there is not any known risk of causing the disease itself. As a result, the DTP vaccine is considered a safe vaccine to use in anyone and it generates a much more targeted immune response specific for the pathogen of interest.
Influenza vaccines, colloquially known as flu shots, are vaccines that protect against infection by influenza viruses. New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes. While their effectiveness varies from year to year, most provide modest to high protection against influenza. Vaccination against influenza began in the 1930s, with large-scale availability in the United States beginning in 1945.
Max Theiler was a South African-American virologist and physician. He was awarded the Nobel Prize in Physiology or Medicine in 1951 for developing a vaccine against yellow fever in 1937, becoming the first African-born Nobel laureate.
Mumps vaccines are vaccines which prevent mumps. When given to a majority of the population they decrease complications at the population level. Effectiveness when 90% of a population is vaccinated is estimated at 85%. Two doses are required for long term prevention. The initial dose is recommended between 12 and 18 months of age. The second dose is then typically given between two years and six years of age. Usage after exposure in those not already immune may be useful.
A breakthrough infection is a case of illness in which a vaccinated individual becomes infected with the illness, because the vaccine has failed to provide complete immunity against the pathogen. Breakthrough infections have been identified in individuals immunized against a variety of diseases including mumps, varicella (Chickenpox), influenza, and COVID-19. The characteristics of the breakthrough infection are dependent on the virus itself. Often, infection of the vaccinated individual results in milder symptoms and shorter duration than if the infection were contracted naturally.
Varicella vaccine, also known as chickenpox vaccine, is a vaccine that protects against chickenpox. One dose of vaccine prevents 95% of moderate disease and 100% of severe disease. Two doses of vaccine are more effective than one. If given to those who are not immune within five days of exposure to chickenpox it prevents most cases of disease. Vaccinating a large portion of the population also protects those who are not vaccinated. It is given by injection just under the skin. Another vaccine, known as zoster vaccine, is used to prevent diseases caused by the same virus – the varicella zoster virus.
The Expanded Program on Immunization(EPI) in the Philippines began in 1976 through Presidential Decree No. 996 signed by President Ferdinand Marcos. And, in 1986, made a response to the Universal Child Immunization goal. The four major strategies include:
Hepatitis B vaccine is a vaccine that prevents hepatitis B. The first dose is recommended within 24 hours of birth with either two or three more doses given after that. This includes those with poor immune function such as from HIV/AIDS and those born premature. It is also recommended that health-care workers be vaccinated. In healthy people, routine immunization results in more than 95% of people being protected.
Hepatitis A vaccine is a vaccine that prevents hepatitis A. It is effective in around 95% of cases and lasts for at least twenty years and possibly a person's entire life. If given, two doses are recommended beginning after the age of one. It is given by injection into a muscle. The first hepatitis A vaccine was approved in Europe in 1991, and the United States in 1995. It is on the World Health Organization's List of Essential Medicines.
The rabies vaccine is a vaccine used to prevent rabies. There are several rabies vaccines available that are both safe and effective. Vaccinations must be administered prior to rabies virus exposure or within the latent period after exposure to prevent the disease. Transmission of rabies virus to humans typically occurs through a bite or scratch from an infectious animal, but exposure can occur through indirect contact with the saliva from an infectious individual.
Pertussis vaccine is a vaccine that protects against whooping cough (pertussis). There are two main types: whole-cell vaccines and acellular vaccines. The whole-cell vaccine is about 78% effective while the acellular vaccine is 71–85% effective. The effectiveness of the vaccines appears to decrease by between 2 and 10% per year after vaccination with a more rapid decrease with the acellular vaccines. The vaccine is only available in combination with tetanus and diphtheria vaccines. Pertussis vaccine is estimated to have saved over 500,000 lives in 2002.
Meningococcal vaccine refers to any vaccine used to prevent infection by Neisseria meningitidis. Different versions are effective against some or all of the following types of meningococcus: A, B, C, W-135, and Y. The vaccines are between 85 and 100% effective for at least two years. They result in a decrease in meningitis and sepsis among populations where they are widely used. They are given either by injection into a muscle or just under the skin.
Measles vaccine protects against becoming infected with measles. Nearly all of those who do not develop immunity after a single dose develop it after a second dose. When the rate of vaccination within a population is greater than 92%, outbreaks of measles typically no longer occur; however, they may occur again if the rate of vaccination decreases. The vaccine's effectiveness lasts many years. It is unclear if it becomes less effective over time. The vaccine may also protect against measles if given within a couple of days after exposure to measles.
Tetanus vaccine, also known as tetanus toxoid (TT), is a toxoid vaccine used to prevent tetanus. During childhood, five doses are recommended, with a sixth given during adolescence.
On 20 January 2016, the health minister of Angola reported 23 cases of yellow fever with 7 deaths among Eritrean and Congolese citizens living in Angola in Viana municipality, a suburb of the capital of Luanda. The first cases were reported in Eritrean visitors beginning on 5 December 2015 and confirmed by the Pasteur WHO reference laboratory in Dakar, Senegal in January. The outbreak was classified as an urban cycle of yellow fever transmission, which can spread rapidly. A preliminary finding that the strain of the yellow fever virus was closely related to a strain identified in a 1971 outbreak in Angola was confirmed in August 2016. Moderators from ProMED-mail stressed the importance of initiating a vaccination campaign immediately to prevent further spread. The CDC classified the outbreak as Watch Level 2 on 7 April 2016. The WHO declared it a grade 2 event on its emergency response framework having moderate public health consequences.