Which of the following vaccines is recommended for healthcare workers to protect against hepatitis B?

Explanation: Cytotoxic T cells (CD8+ T cells) are the effector cells of cell-mediated immunity. Their primary role is to directly recognize and kill infected or abnormal cells, such as virus-infected cells or cancer cells. Cytotoxic T cells release cytotoxic granules containing perforin and granzymes, which induce apoptosis (cell death) in the target cells.

Incorrect choices:

a. Helper T cells, not cytotoxic T cells, recognize antigens presented by macrophages and play a crucial role in activating other immune cells.

b. B cells are responsible for producing antibodies against pathogens during the humoral immune response, not cytotoxic T cells.

d. Regulatory T cells (suppressor T cells) are involved in regulating the immune response to prevent excessive inflammation and tissue damage, not cytotoxic T cells.

Explanation: The pneumococcal polysaccharide vaccine is recommended for older adults to protect against pneumonia caused by Streptococcus pneumoniae bacteria. The influenza vaccine is recommended annually for people of all ages to prevent the flu.

Incorrect choices:

a. The hepatitis B vaccine is not specifically recommended for older adults to prevent pneumonia.

b. The influenza vaccine protects against the flu, not pneumonia.

d. The HPV vaccine is recommended for adolescents and young adults, not older adults, and does not protect against pneumonia.