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How do vaccines work?

Vaccines, which are made from killed, weakened, or partial version of specific pathogens, prime the body’s immune system against future attacks by those pathogens. So, following vaccination, in case of an attack by a particular pathogen, the immune system will recognize it and fight it off.

Which is better: natural immunity or vaccine-acquired immunity?

In some cases, natural immunity is longer-lasting than immunity acquired through vaccination, but the risks of natural infection outweigh the risks of immunization for every recommended vaccine. In addition, some vaccines like tetanus and Haemophilus influenzae type b provide more effective immunity than natural infection.

What is herd immunity?

It’s difficult for a disease to gain a foothold in the community when enough people are immunized against a given disease, thus leading to herd immunity (aka community immunity). So, people who are unable to receive vaccinations are protected, because there is less likelihood of an outbreak that could expose them to the disease.

Why do some vaccines require boosters?

Some vaccines provide lifelong immunity with a single dose, while others require boosters to maintain immunity. Research suggests that if a disease’s progression through the body is very fast, the immune system’s memory response may not be able to respond quickly enough, unless they’ve been primed fairly recently by a booster dose. Additionally, live, attenuated (weakened) vaccines generally offer longer-lasting immunity than killed vaccines, which therefore are more likely to require boosters to maintain immunity.

How many vaccines are currently recommended for children?

The World Health Organization currently recommends 10 vaccines for all children. They are: BCG, Hepatitis B, Polio, DTP, Haemophilus influenza type b, Pneumococcal (conjugate), Rotavirus, Measles, Rubella, and HPV. WHO also recommends additional vaccines for children residing in certain regions and in high-risk populations.

Can an infant’s immune systems handle so many vaccines?

Studies have shown that an infant’s immune system can handle receiving many vaccines at once. The immunity passed from mother to child at birth is not only temporary, but also does not include immunity against diseases like polio, hepatitis B, Haemophilus influenzae type b, etc., which can be prevented by vaccination.

Why is egg allergy a contraindication for some vaccines?

Some vaccines, especially most of the vaccines against influenza, are cultured in chicken eggs. Although the majority of the egg protein is removed during the vaccine-making process, there is some concern of an allergic reaction in individuals with an egg allergy. However, in most cases, only people with a severe allergy to eggs are recommended against receiving egg-based vaccines.

What are the potential side effects of vaccines?

Typically, side effects are mild, such as soreness at the injection site, headache, and low-grade fever. However, serious side effects, including severe allergic reactions, are sometimes possible, but they are extremely rare.


World Health Organization,

The History of Vaccines,

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