Flu Shots Estimated to be 40% Effective in Current U.S. Winter Season, CDC Reports

Health officials in the U.S. have reported that early estimates indicate flu shots are performing reasonably well in the current winter flu season. The vaccines have shown to be approximately 40% effective in preventing adults from falling severely ill due to the flu and requiring medical attention at a doctor’s office, clinic, or hospital. Meanwhile, vaccinated children were found to be around 60% less likely to seek treatment at healthcare facilities, according to the Centers for Disease Control and Prevention (CDC) vaccines meeting on Wednesday, February 28, 2024.

Effectiveness Expectations

Officials generally consider a flu vaccine to be satisfactory if it demonstrates 40% to 60% effectiveness. The success of the shots is often dependent on their compatibility with the prevailing flu strains. In this flu season, the vaccines have appeared to be well-matched, leading to relatively typical effectiveness rates.

Vaccination Rates

Despite the recommendations for annual flu vaccinations for individuals aged 6 months and older in the U.S., only about half of eligible kids and just under half of adults received flu shots in the past several months, based on CDC data. It is essential to increase vaccination rates to ensure better protection against the flu.

Tracking Vaccine Performance

The CDC monitors flu vaccine effectiveness through various systems. They collect data from a network of hospitals to assess how well the vaccines prevent severe flu-related illnesses that necessitate hospitalization. Additionally, outpatient data from urgent care clinics and hospital emergency departments is utilized to gauge the impact of flu vaccines on preventing medical visits due to flu symptoms.

Effectiveness Estimates

Estimates from four different surveillance systems were presented during the recent CDC vaccines meeting. The effectiveness findings, reported as ranges, indicated midpoints at around 40% for adults and approximately 60% for children. These estimates are consistent with the initial reports from the last flu season, signifying stable performance.

Concerns and Considerations

Dr. Sarah Long, a committee member advising the CDC on vaccines, expressed disappointment at the recent effectiveness findings and speculated about potential diminishing returns for annual influenza immunization. There are inquiries into whether repeated yearly vaccinations might be leading to lower immune system responses, but conclusive results are yet to be reached.

Key Message from CDC

Dr. Lisa Grohskopf from the CDC reiterated the importance of getting vaccinated, as it consistently proves to be more beneficial than not being vaccinated. This reaffirms the significance of flu vaccination in public health efforts to mitigate the impact of the seasonal flu.