Without tOPV intensification, although the Rn values remain below 1 at OPV2 cessation, they increase after OPV2 cessation, allowing transmission of increasingly more transmissible OPV-related viruses.
But there is nothing obvious that would point to a more transmissible, more virulent virus, or a change of transmission route.
Virologists, such as Dr Ball at Nottingham, worry that increasing human-to-human transmission is giving Ebola the opportunity to become more transmissible.
For the bacterial pig diseases, estimates of disease introduction via indirect transmission routes were much lower than for the more transmissible viral bovine diseases.
With HBV estimated to be ∼10 times more transmissible than HCV [62], [65], unsafe injections are a possible route of HBV/E transmission.
"But that didn't make it more transmissible or cause more severe disease".
Avian flu now kills about half its known victims -- but flus that become more transmissible generally become less lethal, too.
The mutation slightly changed the shape of the spike, making the virus more transmissible.
Fouchier was unable to confirm the specific mutations that made the virus more transmissible, but said many had already been spotted in the wild.
"The mutations... could cause the viruses to be more transmissible between humans," Peter Palese, a prominent microbiologist at Mount Sinai School of Medicine, wrote recently.
"Some major evolutionary changes would be required to make it more transmissible; not just tweaking around the edges but big changes in the way it behaves.
