2021-22 Influenza vaccine is less effective against current viruses

US interim estimates for 2021-22 influenza The season suggests that the available influenza vaccines did not provide a significant effect in preventing medically associated illnesses in outpatients.

Findings from the new Centers for Disease Control and Prevention (CDC) show avoidance infections and disease burdens caused by the predominant influenza A (H3N2) strain this season. season.

Researchers led by Jessie R. Chung, MPH of the Influenza Division at the CDC National Vaccination and Respiratory Center, have found that the vaccine for this influenza season is effective against mild to moderate acute respiratory infections (ARIs) identified in the laboratory. I tried to estimate the sex. A practice that has been practiced annually by the CDC since 2004-05.

Due to inadequate data during the COVID-19 pandemic, such estimates were not accumulated for the 2020-21 influenza season.

The team interprets vaccine efficacy using interim data from 3636 children and adults diagnosed with ARI enrolled in the Influenza Vaccine Efficacy Network from October 4, 2021 to February 12, 2022. Did. Patient data was collected from one of seven research sites across the United States.

Researchers observed 194 (5%) positive test results for influenza A virus infection via real-time reverse transcription-polymerase chain reaction (RT-PCR). None of the tests for influenza B virus infection were positive. Another 11 patients tested positive for both influenza A virus and SARS-CoV-2 virus. Of the 178 subtyped influenza A viruses, all but one were identified as A (H3N2).

Only 41% of participants who tested positive for the flu were vaccinated against the flu this season, while 50% of those who were negative were vaccinated against the flu. Vaccine efficacy against outpatient medically outpatient ARI associated with influenza A virus was only 14% (95% CI, -17 to 37). Vaccine efficacy was 16% (95% CI, -16 to 39) for subtype A (H3N2).

Influenza A (H3N2) is currently the most prevalent strain in the United States, as previously observed during the 2021-22 influenza season. Although the number of cases remains relatively small compared to past influenza seasons, Experts HCP Live® Its A (H3N2) is a particularly nasty virus subtype.

Tim Uyeki, MD, MPH, and MPP, Chief Medical Officers of the Influenza Division at the CDC’s National Vaccination and Respiratory Center, said last year that the most serious influenza pandemic in recorded history was associated with this subtype. Said.

“The bottom line is that you may be at risk of a fairly serious influenza pandemic from the type A (H3N2) virus, which is how antigenically similar the virus has been exposed to in the past. It depends on what you are doing. Often the H2N3 vaccine strain is mapped to it, “Uyeki explained at the time.

In these latest CDC findings, Chung et al. Found that influenza vaccination rates were also this season among patients in high-risk groups, including pregnant women, toddlers, preschool children, and racial and ethnic minority groups. Pointed out that it remains low.

“The CDC continues to recommend influenza vaccination if the outpatient’s illness (vaccine efficacy) declines. This is for people who have been vaccinated but are still infected. There is increasing evidence suggesting that serious consequences such as hospitalization, ICU hospitalization, and death can be avoided, “they wrote. “In addition, vaccination may prevent illnesses and serious complications of infection with other influenza viruses that may be prevalent later in the season, such as the influenza A (H1N1) pdm09 and B viruses.”

The team identified four study limitations, including limitations on estimation of vaccine efficacy for influenza A and subtype A (H3N2) only. The nature of self-reporting of recording influenza vaccinations. During the COVID-19 pandemic, which affects outpatient care rates, patient health care behavior changed. Limitations of influenza disease evaluated to interpret the efficacy of the vaccine.

That said, the findings show that clinicians should not limit their awareness and response to influenza cases based on the vaccination status of patients this season.

“Physicians should not wait for confirmation of clinical testing for influenza, and the decision to use antivirals should not be influenced by the patient’s influenza vaccination status,” they concluded. “Clinicians need to be aware that influenza activity may continue or increase, and influenza should be considered as a diagnostic potential for all ARI patients.”

the study, “Interim Estimates of Efficacy of Seasonal Influenza Vaccines 2021-22 — US, February 2022”Was published online Weekly morbidity and mortality reports..