COVID-19 hospitalization is a primary measure of the disease’s severity. Hospitalization data shows the risk of severe outcomes is not uniform across all demographics, with age being a significant factor. Age influences the likelihood of an individual requiring hospital care for a COVID-19 infection.
Overall Hospitalization Trends
Since the beginning of the pandemic, COVID-19 hospitalizations have occurred in distinct waves, often corresponding to new viral variants and shifts in population immunity. Data from public health agencies like the Centers for Disease Control and Prevention (CDC) illustrates these periods of intense strain on healthcare systems, followed by intervals of lower transmission and fewer hospital admissions.
While the total number of hospitalizations has fluctuated, the burden has not been static across age demographics. During some periods, a larger proportion of hospitalized patients were younger adults, a shift often linked to vaccination campaigns that first targeted older populations. This dynamic highlights how public health interventions and viral evolution continuously reshape hospitalization trends.
Hospitalization Rates in Children and Young Adults
While children and young adults experience lower rates of severe COVID-19 compared to older individuals, hospitalization is not a rare outcome. Infants under six months old can have hospitalization rates comparable to those of adults aged 65-74, particularly during Omicron waves. This vulnerability is notable because these infants are too young for vaccination, highlighting the importance of maternal vaccination during pregnancy to confer passive immunity.
For older children and adolescents, the risk, while lower than for adults, is still significant. The hospitalization rate for adolescents aged 12-17 was 2.5 to 3 times higher than rates associated with influenza in a typical season. Nearly one-third of adolescents hospitalized with COVID-19 required admission to the intensive care unit (ICU), and a small percentage needed mechanical ventilation, underscoring the potential for severe disease.
Among young adults, aged 18 to 49, hospitalization patterns have shifted throughout the pandemic. After vaccines became widely available to older populations, this age group accounted for a significant portion of total COVID-19 hospitalizations. A CDC report indicated they made up over 40% of admissions during a period in 2021, as the sheer number of infections in this large demographic translated to a substantial number of hospital admissions.
Hospitalization Rates in Middle-Aged and Older Adults
The risk of being hospitalized for COVID-19 increases sharply with age. Middle-aged and, most notably, older adults face a disproportionately high burden of severe disease. This trend has remained a constant feature of the pandemic, even as new variants have emerged and population immunity has grown.
According to CDC surveillance data from late 2023 to early 2024, adults aged 65 to 74 had hospitalization rates over seven times higher than adults aged 18 to 49. For those aged 75 and older, the rate was more than 24 times higher. During this period, individuals 65 and over accounted for 70% of all adult COVID-associated hospitalizations.
This elevated risk translates into a significant public health concern, as severe outcomes are concentrated in this demographic. Among all in-hospital deaths from COVID-19, nearly half occurred in patients aged 75 and older. The data underscores that advancing age is a primary driver of severe COVID-19.
Factors Influencing Age-Related Disparities
The differences in hospitalization rates across age groups are largely driven by biological factors. One primary mechanism is immunosenescence, the natural decline in immune system function associated with age. As people get older, their immune response becomes less robust, which can lead to higher viral replication and a more severe disease course.
Another contributor is the increased prevalence of comorbidities in older populations. Chronic conditions become more common with age and can weaken the body’s defenses, making an individual more susceptible to a severe response from a COVID-19 infection. These conditions include:
- Heart disease
- Diabetes
- Obesity
- Respiratory illnesses
Data from hospitalized patients shows a high percentage, often over 80%, have at least two underlying medical conditions.
The Role of Vaccination and Variants
The landscape of COVID-19 hospitalizations has been significantly shaped by vaccination and the evolution of the virus. Vaccination is a powerful tool for reducing the risk of severe outcomes across all age groups. Data shows that unvaccinated individuals have a much higher likelihood of being hospitalized compared to those who are vaccinated; for instance, adolescent hospitalization rates were found to be ten times higher in the unvaccinated.
Different viral variants have also influenced hospitalization patterns. For example, the intrinsic severity of the Delta variant contributed to high hospitalization rates. In contrast, the increased transmissibility of Omicron led to massive waves of infection that, despite a lower individual risk of severe disease, still strained hospital systems due to the sheer volume of cases. The interplay between vaccination status and the dominant variant creates a dynamic picture of hospitalization risk.