Surprisingly, the child had no detectable circulating virus, no detectable anti-HIV antibodies, and was clinically healthy.
So far this year, however, there's little sign of seasonal flu in the U.S., where nearly all of the circulating flu virus is H1N1, or swine flu, Frieden said.
Their dalliances with younger women keep the virus circulating between generations.
Feeding off a mix of millennial angst and residual technophobia, Wobbler is just one of numerous virus hoaxes circulating by e-mail.
The presence of bluetongue virus will not be confirmed in Scotland until there is sufficient evidence to show that the virus is circulating.
Although the pandemic has been declared by officials as over, the virus is still circulating.
Over the past decade 15 billion doses of polio vaccine drops have been given and there have been 200 confirmed cases of circulating vaccine-derived polio virus.
Every year, influenza kills tens of thousands of Americans, and there is no reason to take the many strains of the virus that are circulating lightly.
FORBES: The Flu Shot's Not A Great Vaccine, But You Should Get One Anyway
The Scottish Government said it was an isolated case and the virus was not circulating between susceptible animals as vector activity was low at this time of year and in the current temperatures.
The children were infected with a virus known as swine influenza A H1N1, which has a unique combination of genes not previously seen in flu viruses in either humans or swine - although it shares similarities with a virus that has been circulating in pigs since 1999.
It is circulating in poultry stocks, but is considered a "low pathogenic" virus that is not sickening birds.
In addition, while this year's vaccine was considered a good match for the most common circulating flu viruses, it only provided 47% protection against H3N2, the main virus.
Flu shots are thought to be 80% effective at preventing infection against the virus contained within them, but health officials have to guess which strains of flu are circulating.
When levels of the virus began to rise in October 2012, it saw a "cocktail of different strains" circulating.
BBC: New strain of winter vomiting bug norovirus: Sydney 2012
应用推荐