The first wave in 1918 was relatively mild, many experts speculate, because the virus had not fully adapted to humans.
Johnson hopes to get permission to start clinical trials soon and is optimistic that the technique can be adapted to humans.
But even if this virus were to peter out soon, there is a strong possibility it would only go underground, quietly continuing to infect some people while becoming better adapted to humans, and then explode around the world.
The spread of the virus within a family in Britain, and the more mild symptoms seen in one patient, have heightened concerns that the infection might become better adapted to humans and spread more easily from person to person.
The speed with which the virus adapted to humans underlines the importance of having a public health surveillance system to recognize and isolate patients at an early stage before a new virus has honed its attack skills.
In the last year, dozens of H5N1 cases have been confirmed in toddlers, almost all of whom have survived — which led some experts to speculate that those are cases of a less lethal version of H5N1 that is better adapted to humans.
Less blooming strains, that are less adapted to humans, may become good starting strains for the next outbreak, resulting in a backset after one outbreak, as observed in Figs 5b and 6b and Supplementary Fig. 2. Hence, the evolutionary change focusing on strains belonging to a single outbreak looks higher than those belonging to multiple outbreaks, giving a steeper slope.
