Vaccines work by training and preparing the body’s natural defences – the immune system – to recognize and fight off viruses and bacteria. If the body is exposed to those disease-causing pathogens later, it will be ready to destroy them quickly – which prevents illness. When a person gets vaccinated against a disease, their risk of infection is also reduced – so they’re also less likely to transmit the virus or bacteria to others. As more people in a community get vaccinated, fewer people remain vulnerable, and there is less possibility for an infected person to pass the pathogen on to another person.

‘Herd immunity’, also known as ‘population immunity’, is the indirect protection from an infectious disease that happens when immunity develops in a population either through vaccination or through previous infection. In communities with high immunity, the non-immune people have a lower risk of disease than they otherwise would, but their reduced risk results from the immunity of people in the community in which they are living (i.e. herd immunity) not because they are personally immune. When vaccine coverage is very high, the risk of disease among those who are non-immune can become similar to those who are truly immune.

The World Health Organization (WHO) supports achieving ‘herd immunity’ through vaccination, not by allowing a disease to spread through a population, as this would result in unnecessary cases and deaths.

Disponível em:<http://crp.com.pe/en/folleto/how-do-vaccines-protect-individuals-and-communities>. Acesso em: jun. 2021. Adaptado.

According to the text, fill in the parentheses with T (True) or F (False). It’s stated in the text that

( ) Vaccines work by improving a person’s immune system.

( ) The risk of a vaccinated person being infected by the disease is zero.

( ) Vaccinated people don’t usually pass the virus or bacteria to others.

( ) Vaccines protect people against harmful diseases before they come into contact with them.

The correct sequence, from top to bottom, is