Vaccination and Immunity

Smallpox is the only human disease to have been completely eradicated from the world through a successful global vaccination campaign led by WHO, with the last natural case occurring in 1977. Tetanus remains a threat through soil contamination, rabies still exists in animal populations, and polio continues to circulate in a few countries.

This describes the principle of immunization, where memory immune cells recognize pathogens from previous exposure and mount a stronger, faster response. Infection refers to the initial invasion, prevention is stopping disease before it occurs, and disease spread refers to transmission between people.

Childhood immunization programs administer vaccines, which contain weakened or inactivated pathogens to stimulate protective immune responses without causing disease. Medicines treat existing conditions, narcotics are controlled substances, and antibiotics kill bacteria but do not prevent viral infections.

When you have a cold or cough, you should avoid crowded places to prevent spreading germs and use a handkerchief when sneezing to trap droplets. Childhood immunization helps prevent diseases but isn't a direct cold/cough precaution, and preventing mosquito breeding is for malaria/dengue, not respiratory illnesses.

Vaccines contain weakened or killed pathogens (or their parts) to stimulate immunity without causing disease. They are preventive tools that stop infections rather than spread them. The other options (vectors, contact, air) are all valid transmission routes for infectious agents.

Immunization (vaccination) introduces weakened or killed pathogens to stimulate immune memory, preventing future infections. Medicines treat active diseases, tonics are general health supplements, and while pure water prevents some water-borne diseases, immunization is the specific medical prevention method listed.

Vaccines work by priming the immune system to recognize and fight specific pathogens before actual infection occurs. They are preventive tools, not treatments for diseases that have already developed.

The DPT (Diphtheria, Pertussis, Tetanus) or 'triple vaccine' protects against these three serious bacterial diseases. Whooping cough is the common name for pertussis. Measles, rubella, and smallpox are covered by different vaccines (MMR, measles, smallpox).

The pneumococcal vaccine encompasses capsular polysaccharides from Streptococcus pneumoniae, and represents a non-viable vaccine, which cannot lead to infection.

These diseases cannot be prevented by vaccination.

The phrase a virus is a non-essential element in the sentence and needs to be set off with commas.

Vaccine clinical trials follow the standard three-phase system: Phase I tests safety and immunogenicity in small groups, Phase II assesses immune response and safety in larger groups, and Phase III confirms efficacy in thousands of subjects. Some vaccines may have Phase IV for post-marketing surveillance.

Whooping cough (pertussis) is an infection of the respiratory system caused by the bacterium Bordetella pertussis. DPT refers to a class of combination vaccines against three infectious diseases in human; diphtheria, pertussis (whooping cough) and tetanus. The vaccine components include diphtheria and tetanus toxoids, and killed whole cells of the organism that causes pertussis.

The varicella vaccine is a live (attenuated) virus that protects against the viral disease commonly known as chickenpox caused by the varicella zoster virus (VZV). The varicella vaccine is marketed as varivax in the U.S and globally as varilrix by glaxosmithkline. Another vaccine that is known as Zostavax is simply a larger than normal dose of varivax, and is used to reduce the risk of shingles also called herpes zoster and postherpetic neuralgia that are caused by the same virus.

An antigen is a substance (usually protein or polysaccharide) that stimulates antibody formation when introduced into the body. It is the triggering molecule for immune response, not the antibody itself.