Young adults are at higher risk of serious illness due to infection than school-age children-ScienceDaily

The study, led by the London School of Economics and Tropical Medicine, analyzed data from 32 different infections, 19 viral and 13 bacterial diseases, and used case fatality and hospitalization rates at different ages. I searched for a pattern of severity.

The severity of most infections was found to be lowest in school-age children (5-14 years). Surprisingly, many diseases such as polio, scab, HIV, tuberculosis, typhoid fever, and meningococcal meningitis were more severe in young adults in their twenties than in school-age children. ..

Some infections, such as COVID-19, SARS, plague, hepatitis A and hepatitis B, have a slower increase in severity with age after childhood, but for most infections this increase is more than in old age. It starts a long time ago. Dengue was the most serious infectious disease in school-age children.

These findings suggest that “immune aging” begins much earlier than previously thought, and by the age of 20 the severity of many infections after childhood may increase. .. Researchers say these results can have a significant impact on their resilience to infection, optimal vaccine schedules, drug design, and understanding of health protection policies throughout their life course.

Professor Judith Grin, lead author of the London School of Economics and Tropical Medicine, said: “Infants are particularly vulnerable to infections because their immune system is immature, and older people are vulnerable to weakened immunity. Surprisingly, their response to infections is at these extreme ages. How it changes between can be attributed to other aspects than immune function. “

To uncover patterns of severity of these diseases in different age groups, researchers collated more than 140 datasets with information on the severity of diseases of more than 30 different bacterial and viral infections. .. These included pre-antibiotic and pre-vaccination era studies to understand the natural response to infection.

They found that most illnesses are the least severe in school-age children, but often increase in severity in young adults. By the age of 20, the severity of polio, typhoid fever, tuberculosis, measles, smallpox, chickenpox, HIV, infectious mononucleosis, and yellow fever was high.

Infectious diseases that have become more severe after the age of 20 include Ebola hemorrhagic fever, meningococcal meningitis, cholera, scarlet fever, and Lassa fever. Some had a slower increase in severity after childhood, including seasonal influenza, brucellosis, and acute hepatitis B infection, which was more common since the age of 30.

For SARS, COVID-19, MERS-CoV, and hepatitis A, the severity of the disease increased from age 40. COVID-19 and SARS have more extreme age-related severity than other infectious diseases, are very mild diseases, mainly in children, and appear to be more lethal in the elderly.

Professor Grin added: “Unusually, information about age-specific responses to infectious diseases has never been compiled for a wide range of infectious diseases, and the reasons for changes in severity other than extreme age have been poorly investigated. Our results suggest a peak immune response that reaches school age and begins to decline much earlier than currently thought, and in some cases from age 15, and also for some vaccines. There are also age patterns of immune responses, how the body handles persistent ones. In viral infections, and immune markers, these together support our interpretation. “

Adolescents and adults may be exposed to high doses of infectious pathogens, which increases the risk of infection, but their relationship to disease severity is inconsistent and infectious doses are severe throughout adulthood. Can’t explain the continuous rise.

Comorbidities also tend to increase with age, but they are generally low in young adults and rarely explain the increase in severity.

Further research is needed to inform new approaches to drug and vaccine design on the mechanisms of immune aging and how school-aged children can increase their ability to resist infection. Understanding the different resilience of children and adults to infectious diseases should guide policies, including vaccination schedules and the role of school closure.

Researchers acknowledge the limitations of this study. Many reports were clinically diagnostic, based on surveillance data, or limited to inpatients. Finding enough detailed age-specific information for various diseases has not been easy, and formal systematic reviews have not been possible. Few studies have been done to investigate the effect of age on disease outcomes, so researchers collated information from different types of studies. To ensure impartial reporting, all identified studies with sufficient information were included in the review, regardless of the age pattern they presented.