Trending Clinical Topic: Flu

Ryan Syrek


December 10, 2021

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As the potential for another wave of COVID-19 looms, attention has also been focused on vaccination for influenza in the hopes of avoiding a compound pandemic. A new study on simultaneous COVID-19 and flu vaccination, research on postoperative outcomes in patients with COVID-19 who received flu vaccination, and several other flu-related findings resulted in this week's top trending clinical topic. A study that included 697 adult volunteers investigated the outcome of receiving an mRNA vaccine or a viral-vector vaccine at the same time as an influenza vaccine (see Infographic below).

The study was published in The Lancet and found that most reactions to the shots were mild or moderate. The research team suggests that simultaneous administration at a single appointment "should reduce the burden on health-care services for vaccine delivery, allowing for timely vaccine administration and protection from COVID-19 and influenza for those in need." The hope is to have a flu season as quiet as the one seen in the United States last year. In the 2019-2020 season, more 22,000 people in the United States died of influenza. Last year, deaths decreased to about 700.

This year, all the flu vaccines in the United States are four-component (quadrivalent) shots. Both the egg-based vaccines and the cell- or recombinant-based vaccines target two influenza A strains and two influenza B strains. Options include injections or a nasal spray. The Centers for Disease Control and Prevention says it expects about 58.5% of the population to get a flu shot this season, up from about 54.8% last season and 51.8% in the 2019-2020 season.

The benefits of influenza vaccination extend beyond the potential to avoid the flu. Patients who have COVID-19 and require surgery appear to have fewer complications if they have been previously vaccinated against influenza, says new research. In a preliminary study that has not yet undergone peer review, researchers analyzed outcomes after various types of surgery on nearly 44,000 COVID-19 patients worldwide, half of whom had received a flu vaccine in the previous 6 months. Those vaccinated against influenza had significantly fewer serious blood infections, fewer potentially life-threatening blood clots in their veins, fewer serious wound-healing problems, and fewer heart attacks. The flu vaccine was also linked with lower rates of stroke, pneumonia, and death.

Although simultaneous COVID-19 and influenza vaccines are safe, a recent study suggested a potential concern with same-day administration of flu and shingles shots. People who got the zoster (shingles) vaccine the same day as their annual influenza shot were more likely to skip their flu shot the following year than people who got the two shots on separate days. The findings suggest that individuals mistakenly think adverse effects commonly related to the zoster vaccine — including chills, fever, pain, and nausea — are caused by the flu vaccine. The study involved 89,237 people with an average age of 72 years. Those who had both shots the same day (n = 27,161) were significantly less likely than those who got them on different days (n = 62,076) to get their annual flu shot the next (2019-2020) flu season (87.3% vs 91.3%; adjusted odds ratio, 0.74; 95% CI, 0.71-0.78; P < .001). Results were similar across subgroups.

As everyone waits to see whether this year's flu season is as relatively nonexistent as last year's, interest in vaccination-related information is high. From studies with direct bearing on COVID-19 to research into other concerns, flu-focused news resulted in this week's top trending clinical topic.

Learn more about influenza vaccination.


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