For protection against: Tetanus and diphtheria (Td); those diseases plus whooping cough (Tdap)
It's crucial because: You may have gotten Td before, but immunity wears off, so you need booster shots. Tdap also protects against whooping cough, which is highly contagious. Though not usually serious in adults, it can be deadly in babies, who typically catch it from grown-ups.
You need it if: It's been 10 years since your last Td vaccine. You're under 65 and have never had a Tdap. Get one instead of your next Td. You're around infants, and it's been 2 years or more since your last Td. Get a Tdap now.
For protection against: Measles, mumps, and rubella
It's crucial because: Though these diseases had almost vanished in the United States, international travel and reduced vaccination rates have resulted in outbreaks here in recent years, making MMR vaccination essential.
You need it if: You were born between 1957 and about 1975 and/or have never had an MMR series—especially if you're around infants (who aren't immunized until after age 1).
For protection against: Pneumonia, and its complications, such as meningitis
It's crucial because: The pneumococcal vaccine fights pneumonia and its complications, which can be life threatening in the very young, the very old, and those with underlying health problems.
You need it if: You're 65 or older. You have asthma, diabetes, heart disease, liver disease, or other serious health problems. You smoke.
For protection against: Shingles
It's crucial because: The chickenpox virus, which stays in your nerves for life, can reawaken and cause shingles. Since about 98% of people ages 20 or older were exposed to chickenpox, virtually everyone should get the herpes zoster vaccine eventually.
You need it if: You're 60 or older. Shingles is most likely to strike older adults, due to their declining immunity.