To assess the effectiveness of flue vaccine for city residents, Mr. Carlson wants to administer vaccine injections to all city residents rather than give half of them a placebo injection. Mr. Carlson is most clearly underestimating the importance of

Flue

Explanation:

The flue is common and a viral infection. It can be deadly and can occur in high groups of people. It attacks a person's throat, neck, and nose. In this disease people like pregnant women, children, older people and the people who have a low immune system would be at a high risk of infection.

Symptoms:

It spread easily It is preventable by the vaccine It can be self-diagnosed It can be treated easily.