New flu viruses

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 October 22, —CDC today reported two new U. One of these variant influenza virus infections is the first to occur during the flu reporting season i. Variant virus infections occur rarely, and usually in the context of exposure to pigs when they happen. However, there have been a small proportion of such infections where the original source of exposure to a pig cannot be readily identified.

When this happens, the possibility of limited human-to-human spread of a variant influenza virus cannot be ruled out.

That means the virus may have passed from a pig to an intermediary person who then spread the virus to the patient in whom the virus was detected. There is epidemiologic follow-up for every case reported to try to identify any such intermediary persons and to make sure there is no ongoing spread of the virus in question. Of the two just-reported variant influenza virus infections, one of the patients had contact with pigs prior to illness onset; but in the other case, no known direct or indirect swine exposure has been identified.

It is possible that limited human-to-human spread occurred in this case, however, no ongoing human-to-human spread has been identified with either patient.

These viruses have important antigenic and genetic differences from seasonal influenza A viruses that circulate worldwide among people.

The two newest infections, one an H3N2v virus and the other an H1N1v virus, occurred in children. Neither child was hospitalized, and both have recovered or are recovering from their illness.

Illnesses associated with variant influenza virus infections have been mostly mild with symptoms similar to those of human seasonal influenza. However, variant influenza virus infections also can cause serious illness, resulting in hospitalization and death. Flurona is not a distinct disease or a new variant, said Dr. Petersburg, Fla. The proper term is "co-infection," which describes when a patient is diagnosed with more than one pathogen simultaneously.

Co-infections are more common than you might think. Long before the recent wave of flurona coverage, doctors were encountering all different types of COVID co-infections. In a Journal of the American Medical Association study published in April , researchers identified COVID patients who were co-infected with viruses including rhinovirus and enterovirus which are often the culprits behind the common cold , adenovirus which can cause cold or flu-like symptoms , and respiratory syncytial virus RSV , which can cause severe disease in young children and older adults.

Cases of flurona have also been reported throughout the pandemic, even as early as February , when a man in Queens, N. Widespread awareness of the phenomenon started to pick up last week, after the Times of Israel announced that a pregnant woman came down with a co-infection that the publication dubbed flurona. For the time being, co-infection with COVID and influenza is rare, and it will likely remain that way if flu activity continues to be suppressed.

During the past two years, the United States and much of the rest of the world have experienced historically low influenza levels. The flu seemed to be kept at bay by all the COVID precautions used during the pandemic, such as lockdowns, masking and social distancing. As social distancing measures relaxed in the fall of , many experts feared the flu season would return with a vengeance, considering that flu vaccinations were down and the general population had reduced immunity to the virus.

While the flu season has so far been less severe than many feared, that could quickly and easily change. Flurona will likely become a more common occurrence if it does, said Dr. Soniya Gandhi, infectious disease specialist and associate chief medical officer at Cedars-Sinai in Los Angeles.

But some flurona cases may fly under the radar. It would be challenging to know that you have a co-infection without being tested for both, and a health care provider typically conducts flu tests. Patients with a mild COVID infection who aren't admitted to a hospital may never find out if they had a case of flurona. Due to the low level of flu activity, too few cases of flurona have been studied to grasp its potential effects on patients.

Influenza and COVID are respiratory viruses that attack the same region of the body: the nose, throat and lungs. Also, patients with compromised immune systems or underlying medical conditions are more susceptible to severe infections with both viruses. Will that spur more severe disease? I think the jury is still out on that, but that's the fear," Messina said. Fortunately, there are treatments available for both viruses. To avoid the possibility of flurona altogether, or to blunt its potential harms, vaccines make all the difference, according to Messina.

And, of course, kids over the age of 5 can be vaccinated for coronavirus as well," Messina said.