21.   Participants who received the weakened vaccine had moderately lower amounts of antibodies to the Nanchang strain of influenza virus.

22.   Researchers propose the culprit is a super-antigen that provokes a far more ferocious immune response than, say, your simple, garden-variety influenza virus.

23.   Right now, the WHO is on the alert for a new influenza virus, he says.

24.   Salk had become interested in the influenza virus while in medical school.

25.   Scientists have come to expect the influenza virus to do the unexpected.

26.   Sanitary workers had to disinfect the entire laboratory to prevent contamination of influenza viruses with rickettsia and accidental rickettsial infections among the influenza workers.

27.   So far such analyses show that all viruses from the human cases contain only avian genes and none from a human influenza virus.

28.   Such changes also allow influenza viruses to evade antibodies, proteins that the immune system, primed by earlier infections, produces to protect against repeat attacks.

29.   That strain of influenza virus is the first to jump from birds to humans without going through other animals.

30.   That would spare those with HIV from the vaccine and lower their chances of exposure to the influenza virus itself.