Vaccines completely revolutionized public health when they were first created by Edward Jenner in 1796. They have protected billions of people worldwide against harmful and fatal viral diseases, even successfully eradicating diseases like smallpox and rinderpest.
Over the last 50 years alone, vaccines have saved 101 million children’s lives around the world, according to estimates from the World Health Organization (WHO).
Vaccines are available to protect against more than 30 life-threatening diseases and infections.
The WHO recommends that every child should get vaccinated against 12 of those diseases: tuberculosis, hepatitis B, polio, diphtheria, tetanus, pertussis, Haemophilus influenza type B, pneumococcal disease, rotavirus, measles, rubella, and human papillomavirus.
Then there are other optional vaccines which protect against diseases like seasonal flu, COVID-19, and tick-borne Encephalitis.
But which vaccines require boosting and which ones provide lifelong protection? And when should you take them to get the best protection?
In this article, we’ll explain what you need to know about how vaccines can protect you against some of the world’s deadliest diseases.
MMR vaccines for measles, mumps and rubella
Measles was declared eliminated in several countries, including the US in 2000. However, vaccine uptake in many regions has dipped below the 95% immunization target, which is required to achieve herd immunity in a population.
As such, measles is making a global comeback — outbreaks are happening around the world.
There are individual vaccines to protect against measles, mumps and rubella, however, these are often administered together in a single MMR vaccine.
The MMR vaccine is usually given in two doses and is recommended in children from six months of age. It’s considered 96% effective against measles, 86% against mumps, and 89% against rubella.
Quick facts
- Administered from at least six months of age.
- Requires two doses to provide lifelong protection.
- The WHO recommends vaccination for all children against measles and rubella, which are usually delivered together with the mumps vaccine.
Infections and mortality
- Measles is seeing a resurgence, with outbreaks occuring in many countries.
- 10.3 million people were infected globally with measles in 2023, and 107,500 people died.
- 17,865 rubella cases were recorded in 2022.
- Approximately 500,000 mumps cases are reported to the WHO every year, but this is not a notifiable disease in most countries.
About the vaccine
The MMR vaccine contains live attenuated viruses for each of its three targets. Live attenuated viruses train the immune system to kill a live virus if you become infected. They contain significantly weakened versions of these viruses, making them targets for the human immune system to recognize and trigger antibody responses, but not cause disease.
Depending on the type of MMR vaccine, they also contain stabilizers like sorbitol, a naturally occurring substance often used as an artificial sweetener, emulsifiers to bind ingredients together, and occasionally small traces of antibiotics.
BCG (Bacillus Calmette-Guerin) vaccine for tuberculosis
The BCG vaccine is recommended in parts of the world with high levels of tuberculosis (TB). TB is a bacterial disease that has been infecting humans for thousands of years. It is likely the single biggest killer among infectious diseases worldwide.
Quick facts
- One dose is administered as soon as possible after birth.
- Protects against Tuberculosis.
- Potential lifelong protection.
Infections and mortality
TB infected 10.8 million globally in 2023, and killed 1.25 million in 2023.
About the BCG vaccine
The BCG vaccine was first developed at the Pasteur Institut in France by Albert Calmette and Camille Guerin in 1900. They eventually produced a viable candidate for trial, which has been in use for more than 80 years. Some countries, such as the US and UK, have low rates of TB and now choose not to include the BCG vaccine in their routine schedule.
The BCG vaccine consists of an attenuated strain of Mycobacterium bovis, the bacterium that causes TB. It is usually administered by applying the liquid vaccination to the upper arm and pricking the skin at the site for it to be absorbed into the body.
HBV vaccine for Hepatitis B
There are several types of hepatitis, but the hepatitis B (HBV) subtype is especially dangerous, causing liver diseases and potentially cancer.
Quick facts
- Administered as soon as possible after birth.
- Protects against Hepatitis B.
- Potential lifelong protection.
Infections and mortality
The WHO estimates that there are 296 million individuals chronically infected with hepatisis B, and approximately 820,000 deaths per year related to the disease. Deaths usually occur from complications caused by the disease, such as liver cirrhosis and cancer.
About the HBV vaccine
The Hepatitis B virus infection affects the liver and can be transmitted from mother-to-child at birth, through sexual activity and bodily fluids, and exposure to needles.
A hepatitis B vaccine is available that provides potentially lifelong protection.
The hepatitis B vaccine is recommended for children around the world. It is usually administered as a multi-dose protocol as soon as possible after birth. It is also recommended as a priority vaccine for patients who require blood transfusions, dialysis and diabetes treatments, organ recipients and those with liver disease, HIV or hepatitis C.
The vaccine contains the inactivated surface antigen of the hepatitis B molecule — the molecule on the outside of the virus that is recognized by human immune cells. The vaccine is produced by inserting the genetic code for this antigen into yeast cells and combining it with ingredients to enhance its effectiveness.
Polio vaccines
Polio was once a devastating disease capable of causing paralysis and death. Vaccine campaigns nearly eradicated the virus, but waning vaccination rates in certain parts of the world risk bringing forms of the disease back.
Quick facts
- Administered in infants from six weeks of age.
- Children typically require four doses to be fully protected for life.
- Two doses in adulthood provide around 90% protection against polio.
- Live and inactivated virus vaccines protect against polioviruses.
Infections and mortality
The Polio Global Eradication Initiative (GEI) reported just 867 wild polio cases in 2024 from official reports and environmental sources, such as wastewater testing.
Types 2 and 3 poliovirus have been eradicated. Only two countries — Afghanistan and Pakistan — have endemic wild-type 1 poliovirus.
This is due to a global health campaign to eradicate polio that began in 1988 and has seen cases decline by 99% globally. The WHO estimates 1.5 million childhood deaths and 20 million cases of immobilizing paralysis have been averted because of this campaign.
About the polio vaccines
There are two polio vaccines: an oral “live-attenuated” vaccine (OPV) and an inactivated virus vaccine (IPV).
The IPV, first developed by US physician Jonas Salk in the 1950s, protects against all three wild-type viruses. This injected vaccine contains dead viral particles.
The OPV was developed by growing the three types of polio viruses on non-human cells to attenuate them. When administered orally, it enables the human immune system to mount a strong response to weak viruses that can’t cause disease.
The oral vaccine does not cause polio in vaccine recipients. However, this weakened form of the virus can build strength in the environment over time if it interacts with many unvaccinated people. As a result, authorities also track “vaccine-derived polio.” The most recent data from the GEI suggested around 900 of these cases were detected in 2024, primarily in Africa and Southeast Asia.
DTP-containing vaccines prevent three infections
Sometimes, vaccines against many different infections are combined into a single course. That’s often the case with so-called DTP-containing vaccines, which exist in different formulations, depending on the country and target group. They protect against diphtheria, tetanus and pertussis (whooping cough).
Quick facts
- Usually administered from six weeks of age.
- First doses usually combine vaccines against diphtheria, tetanus and pertussis (whooping cough).
- Boosters are required to maintain immunity.
Infections and mortality
According to global data from the WHO:
- Diphtheria causes death in around 30% of cases. More than 24,000 cases were reported globally in 2023.
- 25,000 newborns were estimated to have died from neonatal tetanus in 2018. This is a 97% reduction in 30 years. More than 21,000 global cases of tetanus were reported in 2023.
- In 2018, more than 151,000 pertussis cases were reported worldwide.
About the vaccines
Unlike other vaccines recommended from early childhood, DTP vaccines require boosters throughout life to ensure ongoing protection against the bacteria that cause these potentially deadly diseases.
Diphtheria and tetanus vaccines contain inactivated “toxoids” produced by the disease-causing bacteria. The immune system learns to target these toxic products rather than the bacteria themselves.
The pertussis vaccines will either contain a toxoid or an “acellular” vaccine, meaning they introduce specific subunits of the pertussis bacteria for the immune system to fight, instead of a complete bacterial cell.
Rotavirus vaccine
Rotavirus is a common infection that most people have during childhood. It can be very dangerous for newborns and fatal in severe cases.
Quick facts
- Usually administered from six weeks of age
- First doses usually combine vaccines against diphtheria, tetanus and pertussis (whooping cough)
- Protection duration varies
Infections and mortality
The WHO estimates 25 million outpatient visits from healthcare professionals and two million hospitalizations annually result from rotavirus infections in children under five years old.
Studies estimate around 300,000 to 500,000 children die from rotavirus infections each year.
About the vaccine
Rotavirus causes a range of symptoms including diarrhea, vomiting and fever. The rotavirus vaccine doesn’t necessarily prevent rotavirus infection but reduces both the duration and severity of illness from infection.
Rotavirus vaccines are live attenuated vaccines, so they contain weakened rotaviruses to be targeted by a child’s immune system.
Hib vaccines for Haemophilus influenza
Haemophilus influenza is a bacterial infection, of which the “B” subtype (Hib) is considered the most dangerous. While these bacteria can often cause a range of mild infections in the body, Hib has been known to become “invasive”, infecting the bloodstream where it can spread to vital organs and the spinal cord and cause meningitis. It can also cause pneumonia and sepsis.
Quick facts
- A vaccine administered from six weeks of age protects against invasive Hib.
- Long-lasting immunity, but duration of full protection unknown.
Infections and mortality
One study estimated there were 340,000 severe cases and 29,800 deaths in children with Hib infection globally. This marked a 90% decline in estimated cases since 2000.
About the Hib vaccine
Hib vaccines have helped reduce global infection numbers substantially, such that childhood deaths mainly occur in four countries — India, China, Nigeria and South Sudan — where access to immunization is low.
The vaccine comes in several formulations as a “conjugate”, meaning complex sugars from the Hib bacterium are attached to the molecules of other vaccines to generate a better immune response.
Pneumococcal conjugate for pneumococcal disease
The bacteria Streptococcus pneumoniae can cause pneumococcal disease.
Quick facts
- Vaccine administered from six weeks of age.
- Protects against pneumococcal disease. Long-lasting immunity, but duration unknown.
Infections and mortality
Data about pneumococcal disease is less readily available than for other diseases. There were 3.7 million severe cases and 294,000 deaths in children with pneumococcal globally in 2015, half of which occurred in India, Nigeria, DR Congo and Pakistan. More recent estimates suggest around 800,000 people die each year from the disease.
About the pneumococcal vaccines
Pneumococcal vaccines were developed in the 1970s and licensed for the first time in the 1980s. Studies estimate pneumococcal cases halved between 2000 and 2015 thanks to vaccination programs.
There are several different formulations of pneumococcal vaccines used across the world to protect against pneumococcal diseases. These conjugate polysaccharide sugars are from several different types of Streptococcus pneumoniae bacteria, usually diphtheria toxoids.
HPV vaccines for human papillomaviruses
There are around 200 types of human papillomaviruses (HPV). An HPV infection can have a range of effects from causing no symptoms at all, to skin warts or genital herpes, or several forms of cancer. The first vaccine was approved for use in 2006 and was initially targeted towards young adolescent girls to prevent cervical cancer.
Quick facts
- The WHO now recommends HPV vaccine be administered to all children from six weeks of age.
- A “recombinant” vaccine, similar to that used for Hepatitis B.
- Long-lasting protection against common HPV variants
Infections and mortality
WHO estimates from 2019 indicated that HPV was responsible for around 620,000 cases of cervical cancer globally, which is around 70% of all global cervical cancer cases. Cervical cancer is the most prevalent form of cancer in women under 35 years of age.
About the HPV vaccines
The HPV vaccine is a relatively new advancement in health, having become licensed and distributed in the late 2000s. Because of this, research into how long the immunity provided by the vaccine lasts is still being learned through follow-up assessments.
So far, data shows that HPV vaccines provide protection from the virus for at least a decade. A newer form of vaccine called Gardasil 9 has been found to offer at least six years of protection.
The vaccine contains replica surface proteins for several types of HPV, providing safe targets for the immune system to build an antibody response.
Edited by: Fred Schwaller
