Flu virus march 2013 uk

It's bad news for the vaccine, he said. Influenza vaccines protect against four different strains of the flu: H3N2, H1N1 and two strains of influenza B. Hensley's study only covers H3N2, but that happens to be the main circulating strain. The vaccine mismatch may help explain an outbreak of flu at the University of Michigan last month that affected more than people.

That indicates the vaccine was not effective in preventing infection. It's what flu viruses do, Hensley said. Flu viruses mutate all the time—far more than other viruses, including the coronavirus. And different variations can circulate at the same time. But this version of H3N2 has changes that help it escape the antibodies the body makes in response to vaccines. Flu and Covid cases rising in much of the US. Read More. Antibodies are the first line of defense against invaders like viruses, and the current vaccine doesn't seem to generate any of the right antibodies against this new, mutated version of H3N2, called 2a2 for short.

Luckily, the changes are unlikely to affect the second line of defense offered by immune system -- cells called T-cells, so even if the vaccines don't protect against infection, they are likely to protect people against severe disease and death, Hensley said. It's not published in a peer reviewed journal. The US Centers for Disease Control and Prevention has said influenza virtually disappeared last year, but it's coming back this year.

The big fear is a "double whammy" of flu and Covid Both infections occurred in children, one of which had known exposure to swine. Both patients recovered fully. See Influenza A H3N2v virus for more information. Top of Page. These results indicate that vaccination with the flu season vaccine reduced the risk of flu-associated medical visits from flu A H3N2 viruses by one half and from flu B viruses by two-thirds for most of the population.

Overall, VE estimates suggest that the flu vaccine has moderate effectiveness for most people against the flu viruses spreading in the United States, similar to previously published reports. More information about vaccine effectiveness is available at Vaccine Effectiveness — How well does the flu vaccine work? However, VE against flu B was similar to what was seen in other age groups, while VE against flu A H3N2 viruses in people 65 and older was significantly lower than in other age groups.

CDC recognizes the need for developing better flu vaccines in the elderly. Scientists continued to work on better ways to design, conduct and evaluate non-randomized i. CDC has been working with researchers at universities and hospitals since the influenza season to estimate how well influenza vaccine works through observational studies using laboratory-confirmed influenza as the outcome.

These studies currently use laboratory-confirmed medically-attended influenza virus infections as a specific outcome. Similar studies are being done in Australia, Canada and Europe. In May and September , flu vaccine manufacturers originally projected about million doses would be available for the U. Recent updates from manufacturers to CDC indicate that more doses of flu vaccine were actually produced, totaling million doses.

Antiviral resistance means that a virus has changed in such a way that antiviral drugs have become less effective in treating or preventing illnesses caused by the virus. Samples of viruses collected from around the United States and the world are studied to determine if they are developing resistance to any of the antiviral medications currently recommended to treat influenza.

CDC routinely collects viruses through a domestic and global surveillance system to monitor for changes in influenza viruses. However, zoonotic viruses are under strong selective pressure to acquire the ability for human-to-human transmission. Cauchemez and colleagues show that the novel approach described in this paper will be useful in assessing human-to-human transmissions during zoonotic outbreaks.

The researchers developed a mathematical model of disease transmission, which only requires data from routine surveillance and standard case investigations. They showed that the pandemic potential of a zoonotic virus could be estimated simply from the proportion of cases infected by the natural reservoir.

The authors then applied their new approach to assess the human-to-human transmissibility of H1N1v, H1N2v and H3N2v viruses in particular that of the H3N2v-M virus from US surveillance data for the period December to December and Nipah virus in Malaysia and Bangladesh, as well as to a non-zoonotic pathogen Vibrio cholerae in the Dominican Republic. This study demonstrates the applicability of this novel approach to estimating the reproduction number R or the number of individuals infected by a case , during zoonotic and certain non-zoonotic outbreaks.

The technique for estimating R described in this paper is simple and robust and does not require as much investigative effort as existing methods, say the authors. However, a key limitation of this new approach is that it is designed to estimate R during subcritical outbreaks.

If it is not a subcritical outbreak, other methods are needed to estimate R. It is very hard to perform detailed outbreak investigations and effectively trace cases in such settings since visitors are widely dispersed.

The approach presented in the paper, is simple, requires few data, and was very useful in assessing transmissibility of the virus from the data available.