11.   The chances of a smallpox attack are generally deemed to be low, and the vaccine can have severe, even lethal, side effects.

12.   The combined vaccine had similar effects as giving the Hib and hepatitis B vaccines separately, the company said.

13.   The question is whether such vaccines will have the same effect on tumors.

14.   The research showed unequivocally that a vaccine would have to include three distinct types of polio virus, but no more.

15.   The vaccine has mild side effects similar to flu.

16.   The vaccines also had less dangerous, but more common, side effects such as fevers, irritability and sore muscles.

17.   The vaccine has side effects and could be dangerous to those who have compromised immune systems.

18.   Whether the vaccine to be injected into Masters has any promise is a matter of heated debate.

19.   As with human flu shots, the vaccine has to match the strain and the strains change all the time.

20.   Gangarosa and his colleagues explored the impact of the anti-vaccine campaigns on the control of whooping cough and the future role the original vaccine should have.