Similar vaccination campaigns in other countries have reduced the levels of infection by 99 percent over the past 50 years.

If no smallpox attack occurs, it could very well be due to a successful vaccination campaign.

What followed instead was one of the most remarkable vaccination campaigns in history.

In the context of a vaccination campaign, that would be very problematic.

Because measles often led to death in Afghanistan, the vaccination campaign will save at least 35,000 children's lives each year.

But in some vaccination campaigns, a 20-fold higher incidence rate has been reported.

Even so, there are elements of the vaccination campaign that should be modified.

The vaccination campaigns now reach nearly every child under the age of 5.

We know that vaccination campaigns have been effective, but much more that can be done.

The scientists concluded that the risk of an outbreak was too small to justify the vaccination campaign.