This Year’s Flu Shot Is a ‘Good Match,’ CDC Says—But Cases and Hospitalizations Continue to Rise

Low vaccination rates, increased susceptibility to infection, and more holiday gatherings could be behind the spike in hospitalizations.

FAST FACTS

• The influenza vaccine has been carefully tailored to align with the prevailing strains in circulation during this particular season, as affirmed by the CDC director. This alignment underscores its anticipated efficacy in thwarting severe illnesses.
  
• Despite this, there is a concerning escalation in hospitalizations attributed to the flu, primarily stemming from inadequate vaccination rates and the decision of individuals to forgo masks or self-isolation when unwell, as opined by experts.
  
• As the holiday season approaches, it is imperative for individuals to integrate precautionary strategies. These may encompass relocating gatherings outdoors or considering cancellation in cases of illness, thereby safeguarding the well-being of more susceptible demographics such as elderly individuals, infants, and other vulnerable cohorts.

During a press briefing on December 5, Rochelle Walensky, MD, who serves as the director of the Centers for Disease Control and Prevention (CDC), conveyed that this year’s influenza vaccine demonstrates a significant alignment with the strains currently in circulation, indicating a promising level of effectiveness. This announcement coincides with an unusually early and intense flu season that has resulted in a considerable number of hospitalizations for Americans in recent weeks.

The intriguing contrast between the vaccine’s effectiveness and the high prevalence of flu cases can largely be attributed to the diverse approaches people are adopting towards this flu season. Experts have identified two key factors: low rates of vaccination and a rise in individuals engaging in gatherings despite being unwell.

As emphasized in a press briefing by Andrew Pekosz, PhD, a virologist associated with the Johns Hopkins Bloomberg School of Public Health, the value of vaccines lies not merely in their availability but in their administration. He highlighted that vaccines become efficacious when they are administered, actively reducing the potential for disease transmission.

With the flu season in full swing and the holiday period approaching, the concern shifts to how individuals can best shield themselves and their loved ones. Expert insights provide valuable perspectives on the potential of the flu vaccine to mitigate severe illness, the heightened susceptibility of the unvaccinated population this year, and proactive measures to adopt as the flu virus reaches its peak over the forthcoming weeks.

Availability of a Well-Matched Flu Vaccine

Much like the COVID virus, the influenza virus undergoes annual mutations, necessitating corresponding updates to flu shots on a yearly basis.

According to Emily Sickbert-Bennett, PhD, the director of infection prevention at the University of North Carolina Medical Center, the intricate process of vaccine development requires scientists to anticipate the upcoming flu strains by year-end. Despite the variable nature of the flu virus, flu vaccines demonstrate commendable efficacy in curtailing severe illness and averting fatalities.

Even when the flu shot fails to perfectly align with the circulating flu strains, resulting in suboptimal matching, it still holds merit in diminishing the likelihood of flu-related hospitalizations. This perspective was underscored by Dr. Walensky during a briefing.

However, when flu shots effectively mirror the circulating virus strains, as is the situation with the current year’s vaccine, the act of getting vaccinated can lead to a 40%–60% reduction in the risk of requiring medical attention for flu-related concerns.

Dr. Walensky further reinforced this notion by highlighting that even in instances of imperfect matches, there is a 35% decline in hospitalization rates, illustrating the potency of well-matched vaccines. She emphasized the crucial role of proactive vaccination in preventing severe flu-related illnesses and urged people to take action to safeguard their health.

Factors Keeping Flu Cases High, Even With a Good Vaccine

Despite the well-aligned nature of this year’s flu vaccine with the circulating strains, recent CDC estimations reveal a concerning trend. From October 1 to December 3, hospitalizations due to flu ranged from 120,000 to 260,000 individuals, with an accompanying 6 million to 13 million medical visits attributed to flu-related concerns.

Experts elucidate that this phenomenon is a result of heightened susceptibility to the flu, stemming from both controllable and uncontrollable factors. Notably, flu vaccination rates remain disappointingly low; as of October, only 26% of adults had received the flu shot, while late November saw approximately 42.5% of children being vaccinated.

Emily Sickbert-Bennett underscores that while a specific vaccination rate isn’t a magic threshold, an increase in vaccinations corresponds to reduced severity of flu-related illness.

Moreover, the absence of widespread flu infections in the years 2020 and 2021 has inadvertently exacerbated the current situation. Andrew Pekosz explains that viral infections typically enhance immunity against influenza for a duration of one to two years. The lack of such virus-induced immunity leaves a greater portion of the population susceptible, especially those who opt out of vaccination.

The efficacy of flu shots, while commendable, doesn’t reach 100%, as Pekosz clarifies. Yet, despite the prominence of flu-related hospitalizations and cases, the severity of the virus itself might not be the sole driver.

Andrew Pekosz elaborates that the high numbers observed, compounded by their early occurrence, need to be contextualized. When evaluated in relation to the total number of cases, a drastic escalation in the percentage of cases causing severe disease isn’t evident at present.

How to Stay Healthy

As flu-related hospitalizations reach concerning levels, it becomes paramount for individuals to proactively mitigate transmission risks, especially with the forthcoming holiday season and the anticipation of increased gatherings.

Emily Sickbert-Bennett highlights the emotional challenge of canceling events in light of the current environment shaped by the COVID pandemic. Despite these sentiments, the practices employed during COVID to curb transmission can be instrumental in averting flu and RSV spread as well.

Comparatively, the 2021-2022 flu season was notably milder than the ongoing one and even preceding pandemic-era seasons. However, intriguingly, adult flu vaccination rates for this October surpassed those of October 2021 by around three percentage points.

While vaccination rates are an essential factor, it’s crucial to acknowledge that people, in general, are seemingly engaging in fewer preventive measures that otherwise curb viral dissemination, as pointed out by Sickbert-Bennett.

Keri Althoff emphasizes that the preventative measures that effectively addressed COVID transmission can also be applied to mitigate the spread of flu and RSV. This includes measures like hand hygiene, mask usage, relocating holiday gatherings to well-ventilated spaces, and undergoing COVID testing before interacting with vulnerable individuals.

Althoff underscores that during holiday gatherings, considering the susceptibility of individuals across various age groups is pivotal, especially pregnant individuals, children under 2, and adults over 65, who are at higher risk of severe flu complications.

Beyond festivities, wearing masks in public spaces, particularly when feeling unwell, is a prudent approach according to Althoff.

Sickbert-Bennett acknowledges the necessity of personal decisions in navigating interactions and activities, suggesting the availability of masks as a valuable precautionary measure.

In terms of recognizing symptoms and making appropriate decisions, Andrew Pekosz highlights that a negative COVID test result doesn’t necessarily indicate overall health, particularly if influenza-like symptoms like fever, sore throat, and cough are present. Staying home when feeling unwell is paramount, irrespective of the specific virus.

Althoff emphasizes the importance of managing hospitalization rates, a critical indicator of the healthcare system’s capacity. Preventing hospital overload is vital for maintaining quality care for respiratory illnesses and other health concerns.

In line with this, both Althoff and Sickbert-Bennett strongly urge eligible individuals to promptly get their flu shots. Even amidst the ongoing high flu case numbers, the window of opportunity to receive vaccination remains open.

Sickbert-Bennett reassures that the current period is opportune for obtaining flu protection, especially given the ongoing elevated flu activity since October and throughout December.