The U.S. Food and Drug Administration (FDA) has approved four vaccines for use against the 2009 H1N1 influenza virus. The vaccines—made by CSL Limited, MedImmune LLC, Novartis Vaccines and Diagnostics Limited, and sanofi pasteur Inc.—will be distributed nationally after the initial lots become available. This is expected to occur within the next four weeks.

With two new swine flu vaccines approved for use and five million doses scheduled for delivery this month, China is set to become the first country to begin a mass vaccination campaign against the H1N1 pandemic. But officials with the World Health Organization say that there are some concerns about potential side effects.

As manufacturers work furiously to make a vaccine to protect against 2009 influenza A (H1N1) virus, a Rice University bioengineer is trying to improve the process for future flu seasons. The goal is to shorten the time it takes to identify targeted flu strains and manufacture the vaccines for them.

MedImmune is putting its FluMist nasal spray technology to the test against swine flu. FluMist, which got off to a shaky start in the U.S., brought in only $104 million last year, a fraction of what the big global manufacturers have been able to earn with their flu shots. But all those naysayers who scorned the terms of the MedImmune buyout in the face of such weak performance could well be silenced by the rewards available when a pandemic hits. AstraZeneca plans to make 200 million doses of swine flu vaccine by next spring.

Fears about swine flu have spurred more than 3,000 people so far to volunteer to take part in upcoming clinical trials of a new vaccine. That’s already more than the number scientists will need at eight different sites around the U.S. “We don’t generally ever get a response like this,” Dr. Lisa Jackson, the principal researcher in charge of the clinical trials being readied at Seattle-based Group Health Cooperative, which fielded more than a thousand calls from people in two days.