#16,965
For the 4th week in a row, the CDC is reporting on the detection of a novel swine variant infection, this time involving H1N2v in a patient < 18 years of age in Ohio. Unlike last week's case from Oregon, this patient reports visiting an agricultural exhibit at a county fair, albeit on the same day as their symptoms appeared.
This is the 2nd detection of H1N2v in 2022, a subtype that accounts for only about 6% of swine variant infections in the United States over the past dozen years. H3N2v is, by far, the most common.
Most cases have been reported in the Midwest, and have often been associated with county or state fairs, with Indiana and Ohio accounting for roughly 60% of all cases.
Most (but not all) swine variant infections are mild or moderate, and are clinically indistinguishable from regular seasonal influenza. Which is why it is believed many swine variant infections go undetected (see CID Journal: Estimates Of Human Infection From H3N2v (Jul 2011-Apr 2012).
The CDC's Assessment of the Risk from these viruses reads:
CDC AssessmentSporadic infections and even localized outbreaks among people with variant influenza viruses may occur. All influenza viruses have the capacity to change and it’s possible that variant viruses may change such that they infect people easily and spread easily from person-to-person. The Centers for Disease Control and Prevention (CDC) continues to monitor closely for variant influenza virus infections and will report cases of H3N2v and other variant influenza viruses weekly in FluView and on the case count tables on this website
Today's update from today's FluView Report reads:
Novel Influenza A Virus
A human infection with a novel influenza A virus was reported by the Ohio Department of Health. The patient was infected with a swine-origin influenza A(H1N2) variant (A(H1N2)v) virus. The patient is <18 years of age, was not hospitalized, and has recovered from their illness. An investigation by local public health officials found that the patient had attended an agricultural fair on the day of their illness onset. Additional investigation did not identify respiratory illness in any of the patient’s household contacts. No person-to-person transmission of A(H1N2)v virus associated with this patient has been identified. This is the second patient infected with an H1N2v virus reported in the United States in 2022.
A total of five human infections with variant influenza A viruses have been reported in the United States in 2022, including three H3N2v (West Virginia) and two H1N2v (Ohio, Oregon) viruses. When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant” influenza virus. Most human infections with variant influenza viruses occur following exposure to swine, but human-to-human transmission can occur. It is important to note that in most cases, variant influenza viruses have not shown the ability to spread easily and sustainably from person to person.
Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be understood, and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at www.cdc.gov/flu/swineflu/index.htm.
Additional information regarding human infections with novel influenza A viruses can be found at http://gis.cdc.gov/grasp/fluview/Novel_Influenza.html.
While the pandemic risk from swine variant viruses is currently considered low, the CDC's IRAT (Influenza Risk Assessment Tool) lists 3 North American swine viruses as having at least some pandemic potential (2 added in 2019).
H1N2 variant [A/California/62/2018] Jul 2019 5.8 5.7 ModerateH3N2 variant [A/Ohio/13/2017] Jul 2019 6.6 5.8 Moderate
H3N2 variant [A/Indiana/08/2011] Dec 2012 6.0 4.5 Moderate
The CDC maintains a comprehensive Swine/Variant Influenza page where you'll find the latest case counts, safety and prevention information, and guidance for health care providers, including:
- Key Facts for People Exhibiting Pigs at Fairs[545 KB, 2 pages]
- Take Action to Prevent the Spread of Flu Between People and Pigs[1.3 MB, 2 pages]
- Educational Posters[389 KB, 1 page]
- Compendium of Measures to Prevent Disease Associated with Animals in Public Settings, 2013.
- Reduce Your Risk (English)[22 KB, 1 page] | (Spanish)[22 KB, 1 page]
