Biology Now, 2e

32 ■ CHAPTER 02 Evaluating Scientific Claims

SCIENCE

The first trials are

performed on

animals or cell lines.

Three phases of

clinical trials are

conducted on adult

human volunteers.

If the vaccine proves to be safe

and effective, the U.S. Food

and Drug Administration (FDA)

approves it for commercial sale.

The Advisory

Committee on

Immunization

Practices (ACIP)

reviews all data on

the vaccine.

How safe is it?

How effective is it?

How common and

how serious is the

disease it protects

against?

The CDC director reviews the

ACIP recommendations before

adding the vaccine (or not) to the

recommended vaccine schedule.

Every facility that

manufactures the

vaccine is regularly

visited by the FDA.

A new vaccine is

extensively tested:

A vaccine undergoes

extensive review to be

added to the official list

of recommended

childhood

immunizations:

After approval, the

vaccine is continually

tested for safety:

Every batch of

vaccines is tested

for safety, purity,

and potency before

release.

Vaccine Adverse Event Reporting

System (VAERS): Anyone—including

parents, patients, and health care

professionals—may submit a report on

an adverse reaction to a vaccine.

Vaccine Safety Datalink (VSD): Health

care organizations provide data on

vaccinations, and scientists conduct

studies to evaluate the vaccines’ safety.

1

2

3

Figure 2.10

Evaluating vaccines: an ongoing process

Vaccines are continually tested and evaluated for effectiveness, safety, and side effects. The severity of the disease a vaccine

works against, as well as how likely a child is to be infected with the disease, is also taken into consideration in determining

whether to recommend the vaccine.

Q1: Why do vaccine manufacturers begin with tests on animals or cell lines before moving on to adult human subjects?

Q2: What ongoing testing and reporting are vaccines subjected to?

Q3: What do ACIP, FDA, and CDC stand for, and what is the role of each in evaluating vaccines?

values, ethical stances, and religious beliefs

will make some choices more acceptable than

others. For example, if you believe it is not

ethical to eat meat, the scientific finding that

leaner meats are healthier than fattier meats

won’t matter to you.

It is also important to consider how your

choices will affect other people. Choosing not to

vaccinate a child, for instance, affects the entire

community. Rates of vaccination in the United

States have been hovering around 75 percent

because of misconceptions about the safety of

vaccines, and this low level of immunization

puts at risk not only the children who are not

vaccinated, but also those who cannot be vacci-

nated, such as infants too young for a vaccine

or people who are genetically unable to respond

to a vaccine. When a critical portion of a popu-

lation is vaccinated, then the spread of disease

is contained—a concept known as herd immu-

nity (Figure 2.11). In other words, vaccinating a

large number of people keeps germs out of circu-

lation and protects the vulnerable members of

the community.

When parents opt not to vaccinate their

children, herd immunity disappears. And

because of that loss of herd immunity, infec-

tious diseases of the past, some thought to be

eliminated, are roaring back. In August 2013,

a megachurch in Texas whose founder had

spoken out against vaccines made headlines

after 21 members of its congregation contracted