The COVID-19 pandemic shook up typical respiratory pathogens circulation trends and very nearly extinguished the 2020-2021 flu season.1 The following year also saw a somewhat suppressed flu season, but many were predicting a stronger season in 2022-2023. The respiratory season is not yet over—but so far, how has it compared to the previous two years and to historical trends?
When SARS-CoV-2 first began to spread in the United States in early 2020, communities went into lockdown and instituted masking and social distancing measures. During these early days of the pandemic, the circulation of other respiratory pathogens plummeted. Data from BIOFIRE® Syndromic Trends (TREND) illustrate the dramatic drop-off in respiratory circulation.2
Human rhinovirus/enterovirus—the most common cold-causing virus—made a comeback later in 2020, but influenza did not, leading to a nearly non-existent flu season in 2020-2021. The CDC notes that only 0.2% of respiratory specimens tested in the US were positive for an influenza virus during this period, despite high levels of testing.1 In comparison, the previous three flu seasons saw a peak between 26.2% and 30.3% of respiratory tests with influenza-positive results.1
The CDC attributes the dampened 2020-2021 respiratory season to COVID-19 mitigation measures like masking, school closures, reduced travel, and physical distancing, as well as influenza vaccinations.1
These actions may have impacted the 2021-2022 respiratory season as well, according to the CDC, which describes this season as “mild.”3 While the season wasn’t as dormant as the previous year, “the number of cases of influenza-associated illness, medically attended illnesses, hospitalizations, and deaths were the lowest since the 2011-2012 season which was the first full season following the influenza A (H1N1) pandemic.”3
As the United States entered the 2022-2023 flu season, some indications pointed to the possibility of a severe season. In an interview with Bloomberg, Anthony Fauci, the former medical advisor to President Joe Biden, said the United States should prepare for a difficult flu season. He pointed to the Southern Hemisphere for this prediction—the flu season in the Southern Hemisphere often provides a preview of what the Northern Hemisphere will experience, and that region faced a potentially record-setting flu season in terms of infection levels.4
So how has the 2022-2023 flu season shaped up? The numbers are still provisional, and the season is only half completed (flu season can last into May5). However, data from BIOFIRE TREND show that influenza began to rise in the United States in October, hit a peak in very early December, and dropped off by January.2 During the peak, influenza was circulating at higher levels than SARS-CoV-2.
Provisional data from the CDC indicate that the United States racked up 24 – 49 million flu illnesses so far in the flu season, along with 17,000 – 53,000 deaths.6 This compares with a total of 9 million flu illnesses and 5,000 flu deaths in the entire 2021-2022 season.3
Last year’s flu season was characterized by two waves, with the second wave coming in late spring and continuing into mid-June.3 This means that while influenza numbers fell off in early 2023, we are only halfway through the season and should prepare for a possible second wave in the spring. However, COVID-19 has made predicting respiratory circulation a fool’s errand. Or, as the CDC puts it, “the timing and duration of flu activity has been less predictable.”5
The United States has already experienced at least one influenza wave in the 2022-2023 respiratory season and may see another in the spring. Layered on top of that are the continuing COVID-19 pandemic and a resurgence of common respiratory pathogens like human rhinovirus/enterovirus, parainfluenza viruses, and respiratory syncytial virus. While the picture in 2020 was one of suppressed activity for non-SARS-CoV-2 respiratory pathogens, 2021 and 2022 exhibited diverse respiratory activity.2
This variety of respiratory circulation highlights the value of syndromic testing. Instead of testing for just one or two respiratory pathogens, BIOFIRE syndromic testing combines a broad grouping of probable pathogens into one quick test. A comprehensive respiratory pathogen panel makes it more likely for patients and their providers to receive actionable answers in a clinically relevant timeframe.
The BIOFIRE® Respiratory 2.1 (RP2.1) Panel is a multiplex PCR test that identifies 22 common respiratory pathogens, including SARS-CoV-2, influenza A and B viruses, respiratory syncytial virus, and more. Fast, comprehensive answers may help clinicians make crucial patient-management decisions around optimal therapy, admission, discharge, isolation, and cohorting.
The new BIOFIRE® SPOTFIRE® Respiratory (R) Panel is a respiratory PCR test tailored for the needs of outpatient settings. The SPOTFIRE R Panel returns results on 15 respiratory pathogens in about 15 minutes, enabling clinicians to offer their patients the confidence and peace of mind that come with comprehensive, PCR results—all onsite and within the patient visit.
References:
BIOFIRE® FIREWORKS™: The Ultimate Hub for Surveillance and System Data