People who have weak immune systems, such as the elderly, young children, and those with various medical conditions, are most at risk.

If you have a weak immune system to begin with, a vaccine may just not work as well.

But it is a major threat to people with weak immune systems.

But the young, elderly, and people with weak immune systems are more vulnerable.

Those most at risk are small children, older people and others with weak immune systems.

The disease is more likely to spread to other areas of the body in people who have weak immune systems.

Children, the elderly, and those with a weak immune system are most vulnerable.

If you have a weak immune system, treatment might be more difficult.

Our weak judicial system is under reform and being strengthened.

"Is it still affecting only those with weak immune systems?"