Vaccines can be used to protect against both viruses and bacteria. But bacteria have a secret weapon that makes them harder to fight.

Many parents have had questions about childhood vaccines. Yet the research regularly shows them to be safe and effective.

One of the most common reasons for diarrhea among children is rotavirus. But a vaccine for rotavirus was introduced in 2007.

Measles cases are the highest they have been since 2000, exceeding the previous high in 2011. L ike this year's, t he 2011 outbreaks resulted from low vaccination coverage.

Any time a new vaccine is introduced, researchers pay special attention to what happens in the next several decades to the disease that vaccine protects against. Chickenpox is no different.

Vaccines have prevented millions of illnesses, yet some uneasiness about their safety persists for some parents. One of the biggest concerns has been shot down again.

Some parents may feel it's better to delay their children's vaccines instead of following the officially recommended schedule. But that could present more risks from side effects.

Vaccinations can offer protection that prevents disease and saves lives. For HIV-infected patients, this protection may not last as long.

Measles is no longer a widespread issue in the US, but that doesn't mean infections and outbreaks can't occur, as one US state is currently seeing.

Most of the press around the start of flu season focuses on high-risk groups, such as children, the elderly, pregnant women and those working in healthcare. But others are at risk too.