Description
Uprooting advances in medical science, Pediatrics can be protected against more diseases than ever before. Vaccines help the pediatric immune system fight infections more efficiently by sparking immune response to specific diseases.
Summary Listen
- The National Immunization Program was formally established in the 1960s, although vaccines for smallpox, rabies, typhoid, cholera, and plague existed by 1900. Vaccination has led to the virtual disappearance of many childhood diseases. The specific vaccines included in national programs vary across countries.
- The first smallpox vaccine was discovered in 1798 and introduced to India around 1800. The WHO estimates that current immunization programs save 2 to 3 million lives annually, highlighting vaccination as a cost-effective disease prevention tool. Vaccines contain either parts of or whole germs that have been killed or weakened.
- Besides antigens, vaccines include preservatives (like thimerosal), adjuvants (like aluminum salts), and stabilizers (like sugars and gelatin). Proteins are used for virus or bacteria growth, formaldehyde inactivates toxins, and antibiotics such as neomycin prevent bacterial contamination during manufacturing.
- Vaccines stimulate antibody production by the immune system. Memory cells develop after the first encounter with an antigen, providing long-lasting immunity. The goal is to elicit a strong immune response, especially against serious diseases.
- Vaccine types include live attenuated, killed whole organism, toxoid, subunit (purified protein, recombinant protein, polysaccharide, or peptide), and virus-like particle vaccines. Examples include MMR, oral polio, BCG (live attenuated); whole-cell pertussis, rabies, hepatitis A (killed); diphtheria and tetanus (toxoid); pneumococcal, typhoid, hepatitis A and B, influenza, pertussis (subunit); and human papillomavirus (virus-like particle).
- Polio vaccines include oral polio (OPV, live) and inactivated polio (IPV, injectable). OPV initially targeted types 1, 2, and 3, but now only targets 1 and 3 due to vaccine-induced paralytic polio. IPV is safe for immunocompromised individuals and premature babies. Live vaccines cannot be used on immunocompromised people because of uncontrolled replication.
- Immunity types include innate (present at birth) and adaptive (acquired). Adaptive immunity can be natural (through infection or maternal antibodies) or artificial (through vaccination or antibody transfer). Passive immunity is immediate but short-lived. Herd immunity occurs when a large community proportion is immune, protecting the unimmunized.
- Vaccination issues include mild side effects (pain, redness, swelling, fever, headache) and rare severe reactions (anaphylaxis, ITP). There is no documented link between MMR and autism despite early concerns. Vaccines undergo rigorous testing and clinical trials for safety, immunogenicity, and efficacy before public use.
- Edward Jenner initiated vaccination with the smallpox vaccine. By the 1940s, vaccines existed for smallpox, tetanus, pertussis, and diphtheria. BCG vaccination began in India in 1948. In the 1950s, polio vaccines were developed, with both IPV and OPV licensed by 1955.
- In the late 1960s, MMR was added. In 1972, smallpox was eradicated. Between 1985 and 1994, the *Haemophilus influenzae* type b (Hib) vaccine was licensed, and hepatitis B was added to the national program in 1995. Chickenpox, rotavirus, hepatitis A, HPV, and pneumococcal vaccines were introduced between 1995 and 2010.
- Acellular pertussis vaccines (aP) were introduced in 1997 and caused fewer side effects compared to whole-cell vaccines. The oral polio vaccine containing type 2 was discontinued from 2000 due to vaccine-induced paralysis. Current recommended vaccines for babies after birth include BCG, Oral Polio and Hepatitis B. Additional vaccines given over the first year and beyond protect against Diphtheria, Tetanus, Pertussis, Hib, Polio, Pneumococcal, Rotavirus, Flu, Typhoid, MMR, Chicken Pox, and Hepatitis A.
- Vaccines are also important for adults. Pregnant women are advised to get Tdap to protect newborns, and influenza vaccines are recommended for adults, especially those with chronic lung diseases. MMR, chickenpox, HPV, shingles, and pneumococcal vaccines are also advised for adults. COVID-19 vaccines are now also included.
- Trials are underway for vaccines against Group B *Streptococcus* to protect newborns. Respiratory syncytial virus (RSV) and cytomegalovirus (CMV) vaccines are also being researched. Research to reduce antibiotic resistant bacteria is ongoing. Clinical trials for vaccine confirmation typically take about 10 years.
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About the Speakers
Dr Latha Kanchi Parthasarathy
MBBS; DCH; MRCPCH; CCT (London) Senior Paediatrics Consultant,Apollo Hospitals
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