H5N1 may cause more than one influenza pandemic, as it is expected to continue mutating in birds regardless of whether humans develop herd immunity to a future pandemic strain.
42.
The oral vaccine, a relatively safe form of the live virus, is preferred in part because it is contagious and can give what experts call " herd immunity ."
43.
The second reaso is to create something called " herd immunity . " Flu is a highly contagious disease, but you can't get it if you haven't been exposed.
44.
A safer injected vaccine that can't mutate isn't used here because it's more expensive, it has to be given by professionals and it doesn't offer the herd immunity effect.
45.
Determining these values could help determine transmissibility, as well as how large an area would need to be vaccinated if / when a vaccine is developed, to acquire herd immunity.
46.
If enough people hope to become free-riders, gaining the benefits of herd immunity without vaccination, vaccination levels may drop to a level where herd immunity ceases to be as effective.
47.
Given the realities of herd immunity, you could argue that the worst possible public-health situation would be to eradicate a mosquito such as Aedes aegypti and then let it return.
48.
If enough people hope to become free-riders, gaining the benefits of herd immunity without vaccination, vaccination levels may drop to a level where herd immunity ceases to be as effective.
49.
The reason is an unfortunate variable known to epidemiologists as " herd immunity " _ the proportion of the population that has become immune to a virus such as dengue.
50.
Others believe that reducing HPV infection in more men and women, even when it has no symptoms, is important ( herd immunity ) to prevent more cancers rather than just treating them.
