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Vaccines are laboratory-made products that contain harmless forms of a virus or bacteria. It allows long-lasting immunity in individuals against a dangerous and/or deadly disease.
Medications given for specific diseases aid in the treatment and management of the disease. Vaccines prevent individuals from acquiring the disease, to begin with. (1)
Immunization occurs when the immune system of a vaccinated individual has become strengthened enough to protect against a specific disease. (1)
How Does a Vaccine Work?
An infectious pathogen that invades the human body triggers the immune system to mark the viral material, also known as antigens, as foreign, and a robust immune response begins.
When a vaccine is given to an individual in the form of a weakened or killed microbe, inactivated toxoid, or subunit/conjugate form, the viral antigen is effectively introduced to the immune system. Then, the immune system develops protective antibodies and memory T-lymphocytes against the antigen, which allow protection against the specific disease if the vaccinated individual encounters the virus later on. (2)
Different Types of Vaccines
There are four types of vaccines:
- Live, attenuated – The virus used in the vaccine has been weakened or altered in order not to cause illness.
- Killed, inactivated – The virus used in the vaccine is killed before vaccination.
- Toxoid, inactivated toxin – The toxins used in the vaccine are for bacterial diseases that cause illness by a toxin, instead of bacteria.
- Subunit/conjugate – The vaccine contains segments of the infectious pathogen. (3)
The Benefits of Vaccines
The benefits of vaccines are not only protection against a specific virus by strengthening the immune response to infectious pathogens but also prevention of the spread of the disease to others in the community.
Vaccines against previously epidemic-causing infectious diseases, such as measles, pertussis, and mumps, have effectively controlled the spread and mortality from such diseases and have led to close eradication of polio and smallpox. (4)
Vaccines Protect Against Various Diseases
Vaccines are protective against various diseases and are recommended for use in all children and adults.
Individuals who are immunocompromised due to severe illness or have an unknown immune status should not be given a live, attenuated vaccine due to the risk of acquiring disease from the vaccine. Before getting a vaccine, an immunocompromised individual should consult a doctor to determine if the benefits outweigh the risks.
The US Childhood Immunization Schedules has approved the following vaccines for children aged 0–6 years old:
- Live, attenuated vaccines for measles, mumps, and rubella (MMR combined vaccine), varicella (chickenpox), influenza (nasal spray), and rotavirus
- Killed, inactivated vaccines for polio (inactivated polio vaccine, IPV) and hepatitis A
- Toxoid vaccine for diphtheria and tetanus (a part of DTaP combined immunization)
- Subunit/conjugate vaccine for hepatitis B, influenza (injection), Haemophilus influenzae type b (Hib), pertussis (a part of DTaP combined immunization), pneumococcal infections, and meningococcal infections
Other vaccines that are available to the public are the live, attenuated vaccines for zoster (shingles) and yellow fever, inactivated/killed vaccines for rabies, and subunit/conjugate vaccines for human papillomavirus (HPV). (5)
Safety of Vaccination
Vaccines are safe and very effective. Before approval to administer vaccines to the general public, they undergo extensive testing in clinical trials where they are administered and monitored in volunteers for symptomatic improvement and/or adverse effects.
In the United States, the US Food and Drug Administration monitors the safety, effectiveness, and availability of vaccines after it has shown positive results in the clinical trials. Additionally, once a vaccine is approved for use, the FDA continuously monitors the vaccine for safety and efficacy. (6)
Side Effects of Vaccines
Vaccine safety and efficacy are carefully tested in multiple phases of clinical trials to ensure safety to those administered.
Side effects include injection site redness and tenderness, arm soreness, and fever. High fever in children can result in a febrile seizure. Extreme side effects such as severe allergic reactions (anaphylaxis) may also occur. However, vaccination benefits significantly outweigh the risks. (7)
Vaccines That Should Be Taken by an Individual
All FDA-approved and FDA-authorized vaccinations as recommended by the CDC guidelines should be surely taken for the correct groups (child, parent, adults, pregnant, elderly, health care workers, individuals with chronic disease, and immunocompromised individuals) with no other contraindications to the vaccines. (8)
Recommended vaccines include:
- Influenza vaccination
- Measles, mumps, and rubella vaccination
- Meningococcal vaccination
- Pneumococcal vaccination
- Tetanus, diphtheria, and pertussis vaccination
- Varicella vaccination
- Zoster vaccination
- Human papillomavirus vaccination
- Hepatitis B vaccination
- Hepatitis A vaccination
- Haemophilus influenzae type b vaccination
Most-Asked Questions About Vaccines
How many vaccines can a person have at a time?
Multiple vaccinations or vaccination combinations can be safely administered if given routinely following the guidelines and if the recipient does not have any contraindications to the vaccine.
Data on combination vaccines and individual vaccine safety have been studied rigorously before its licensing. (9) A combination vaccine limits the number of times being injected during a single doctor’s visit and has been utilized since the 1940s. (9)
Which vaccines are given to a baby at the time of birth?
At the time of birth, the first dose of hepatitis B (HepB) is given. At 2 months of life, the first doses of rotavirus, diphtheria, tetanus, and acellular pertussis (DTaP: <7 years), Haemophilus influenzae type b (Hib), pneumococcal conjugate, and inactivated poliovirus (IPV: <18 years) vaccines are given.
At 12 months of life, the first doses of measles, mumps, rubella (MMR), and varicella are given. (10)
According to the recent vaccination guidelines, childhood vaccines protect against 14 contagious diseases by the first 24 months of life. These diseases are: (11)
- Rubella (German measles)
- Varicella (chickenpox)
- Hepatitis A
- Hepatitis B
- Pertussis (whooping cough)
- Haemophilus influenzae Type b (Hib)
- Influenza (flu)
- Pneumococcal disease
Are all vaccines needed by everybody?
Vaccinations are recommended for everybody to build immunity to lethal infections, which can further cause severe complications and mortality, and to prevent further the spread of these microorganisms. Vaccination protects individuals and those around them. (11)
How effective are vaccines?
Vaccine efficacy is thoroughly tested in multiple phases of clinical trials to build immunity, provide protection, and prevent infections.
Is it safe to get vaccinated during pregnancy?
Only particular vaccinations are routinely administered beforehand, during, and after pregnancy. Vaccinations stimulate an immune response within the mother’s body, developing antibodies that can then cross the placenta, conferring immunity to the developing fetus. (12)
Vaccinations are a reliable and practical way to stimulate the body’s immune response to build immunity to once-lethal infections before coming into contact with the specific harmful microorganisms. This further prevents one from developing certain diseases (mentioned above) and suffering complications and possible mortality from the disease.
Moreover, vaccination prevents the spread of infections and illnesses to others who may not be fully or partially immunized or immunocompromised who may suffer a more profound disease course or mortality. The benefits of getting routine vaccinations outweigh the risks and are advised for everybody. Vaccinations protect you and those around you.