CREDIT CDC
Between social distancing, facemasks, hand hygiene and a potential suppressive impact from the coronavirus itself (aka `viral interference'), influenza and ILIs in the United States (and globally) have been, and remain, at historical low levels for the entire 2020-2021 flu season (see chart below).
We do continue to see very scattered reports of novel flu viruses jumping from pigs to humans - both in the United States and Canada - and around the world. The assumption is that while extremely rare - given very limited testing and surveillance - only a small percentage are ever detected.
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
While most swine variant infections don't appear to transmit well in humans, more than 470 cases have been reported in the United States since 2005, including clusters of limited H-2-H transmission.
The CDC's Risk Assessment for these viruses reads:
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
Today's CDC FluView reports the 3rd confirmed human infection with a swine variant virus in the United States in 2021, this time H1N2v. The patient, described as under 18 years of age living on a farm with swine present, has completely recovered, and there are no indications of human-to-human transmission.
One human infection with an influenza A(H1N2) variant (A(H1N2)v) virus was reported by Ohio. The patient is <18 years of age, was not hospitalized, and has completely recovered from their illness. Investigation into the source of the infection revealed that the patient lives on a farm with swine present. No human-to-human transmission of A(H1N2)v virus has been identified associated with this patient. This is the first influenza A(H1N2)v virus identified in the United States that occurred in 2021.
Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be more fully understood and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza infection in humans, and strategies to interact safely with swine can be found at http://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.
