Avian Flu Diary: FluView Week 43: Flu Still Climbing & A Novel (H3N2v) Infection In New Mexico

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The CDC has published their weekly FluView Report, and in the last week of October influenza-like illnesses - including influenza and RSV - continued to climb like a homesick angel (see graphic below).

This is the earliest start to a flu season since the H1N1 pandemic of 2009.

The key points from today's report include:

Key Points

Influenza activity continues to increase. Regions 4 (Southeast) and 6 (South-Central) are reporting the highest levels of flu activity, followed by regions 3 (Mid-Atlantic) and 9 (south-central West Coast).

One human infection with a novel influenza A virus was reported by the New Mexico Department of Health.

The second pediatric death of the 2022-23 influenza season was reported this week.

CDC estimates that, so far this season, there have been at least 1,600,000 illnesses, 13,000 hospitalizations, and 730 deaths from flu.

The cumulative hospitalization rate in the FluSurv-NET system is higher than the rate observed in week 43 during every previous season since 2010-2011.

An annual flu vaccine is the best way to protect against flu. Vaccination helps prevent infection and can also prevent serious outcomes in people who get vaccinated but still get sick with flu.

CDC recommends that everyone ages 6 months and older get a flu vaccine annually.

There are also prescription flu antiviral drugs that can be used to treat flu illness; those need to be started as early as possible.

The vast majority (80%) of Influenza A flu viruses sub-typed by the CDC this fall have been H3N2, which tend to dominate during more severe flu seasons, and can be particularly tough on the elderly. While flu seasons are inherently unpredictable, this year's early start - along with the co-circulation of COVID and RSV - are already putting hospitals and emergency rooms under pressure.

This week the CDC is also reporting the 10th reported novel flu virus infection of 2022; a swine-variant H3N2v virus detected in a person < 18 years of age, with swine contact, in New Mexico.

Public Health Novel Influenza A Virus
A human infection with a novel influenza A virus was reported by the New Mexico Department of Health. The patient was infected with an influenza A(H3N2) variant (A(H3N2)v) virus. The illness occurred during the week ending October 15, 2022 (week 41). The patient is <18 years of age and is recovering from their illness. An investigation by local public health officials found that the patient had swine exposure prior to their illness onset. No person-to-person transmission of A(H3N2)v virus associated with this patient has been identified. The investigation is ongoing.
A total of ten human infections with variant novel influenza A viruses have been reported in the United States in 2022, including five H3N2v (Michigan, New Mexico, West Virginia (3)) and five H1N2v (Georgia, Michigan, Ohio, Oregon, Wisconsin) 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.

The CDC's Assessment of Swine Variant Viruses reads:

CDC Assessment

Sporadic 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

Although it is rare to see swine variant viruses spread efficiently in humans, and most cases are mild or moderate, 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).