(UFU - 2022)
How to Compare COVID Deaths for Vaccinated and Unvaccinated People
Looking at COVID data in recent months, it may appear that a significant proportion of the people who have died of COVID were vaccinated against the disease. But it is important to put those numbers in context. Each week in March, on average, a reported 644 people in this data set died of COVID. Of them, 261 were vaccinated with either just a primary round of shots—two doses of an mRNA vaccine or a single dose of Johnson & Johnson’s vaccine—or with that primary series and at least one shot of a booster. Taken at face value, these numbers may appear to indicate that vaccination does not make that much of a difference. But this perception is an example of a phenomenon known as the base rate fallacy. One also has to consider the denominator of the fraction—that is, the sizes of the vaccinated and unvaccinated populations. With shots widely available to almost all age groups, the majority of the U.S. population has been vaccinated. So even if only a small fraction of vaccinated people who get COVID die from it, the more people who are vaccinated, the more likely they are to make up a portion of the dead. In order to avoid the pitfalls of absolute numbers, it is useful to instead look at incidence rates—usually expressed as the number of deaths per 100,000 people. Standardizing the denominator across all groups offers a very different picture.
Another way to think about the protection vaccination provides is to compare the ratios of death rates among the vaccinated and unvaccinated. It is also important to consider the ages of those who are dying. So when you separate the age groups, it becomes even clearer that vaccination reduces the risk of death. An additional factor to consider is that as the pandemic wears on and a disproportionate number of unvaccinated people die from COVID, the unvaccinated population shrinks. This leaves a comparatively larger vaccinated group, leading to an increase in total deaths despite the lower death rate among vaccinated people. No vaccine is 100 percent effective, but immunization reduces the risk of dying from COVID substantially.
Disponível em: http://www.scientificamerican.com/. Acesso em: 11 jun. 2022.
RESPONDA A QUESTÃO EM PORTUGUÊS. RESPOSTAS EM INGLÊS NÃO SERÃO ACEITAS.
Based on the text, answer the following questions.
A) Explain the fact that out of the 644 people who died of COVID, 261 were vaccinated?
B) Identify at least two conclusions presented by the authors in this article?
Gabarito:
Resolução:
A) O fato de 261 pessoas vacinadas terem morrido em decorrência da COVID, em um universo de 644 pessoas, pode ser explicado pelo fenômeno conhecido como ‘falácia da taxa-base’. Tal falácia, ao ignorar o contexto dos números, causa a impressão de que a vacinação é ineficaz. Os números devem, portanto, considerar as taxas de incidência (geralmente expressas a partir do número de mortes por 100 mil pessoas) dentre a população vacinada e não vacinada.
OU
O fato descrito na questão pode ser explicado quando se consideram apenas números absolutos. Contudo, há de se levar em conta o denominador da fração: o tamanho da população vacinada e não vacinada. Quanto maior for a população vacinada, maior a probabilidade de vacinados estarem entre as taxas dos mortos pela COVID.
B) Dentre as conclusões apontadas pelos autores, destacam-se:
i) os dados sobre as mortes por COVID têm que ser analisados, comparando-se as taxas de mortalidade entre os vacinados e não vacinados;
ii) ao considerar a idade das pessoas que morreram por COVID, conclui-se que a vacinação reduz o risco de morte;
iii) à medida que a pandemia avança e um número desproporcional de pessoas não vacinadas morre de COVID, a população não vacinada diminui, aumentando, assim, o total de mortes entre os vacinados, apesar da menor taxa de mortalidade destes;
iv) apesar de nenhuma vacina ter 100% de eficácia, a imunização reduz substancialmente o risco de morte por COVID.
Obs: será atribuída pontuação máxima para os/as candidatos/as que mencionarem integralmente pelo menos duas das conclusões acima.