Swedish researchers have just upended one of medicine's most routine interventions: the prescription of antibiotics for common sore throats. After analyzing data from the entire Swedish population in 2024, scientists at the University of Gothenburg discovered that even aggressive antibiotic strategies prevent only a fraction of the serious infections they're meant to stop.
The findings matter because sore throats are among the most common reasons people visit a doctor, and preventing invasive group A streptococcal infection—or iGAS—has long been cited as a reason to treat uncomplicated cases with antibiotics. iGAS is rare but potentially life-threatening, occurring when the bacteria enter the bloodstream or lungs. Its incidence has been rising in recent years across several countries, fueling the debate around prevention strategies.
But the numbers tell a different story. Ronny Gunnarsson, lead author of the study published in the International Journal of Infectious Diseases and a family physician and professor emeritus at the University of Gothenburg, and his team calculated what would happen under different treatment scenarios. Even in an extreme scenario where every person seeking care for a sore throat was tested and treated if carrying the bacteria, antibiotics would prevent at most 6.7% of iGAS cases in children and just 2.8% in adults. Under current Swedish guidelines, which recommend testing only when patients meet three to four specific symptoms according to the Centor criteria, the preventive effect drops to a maximum of 1.6% in children and 1.2% in adults.
The implication is staggering: between 45,000 and 110,000 patients must receive throat swabs and up to 110,000 antibiotic prescriptions must be written just to prevent a single case of iGAS. "The proportion of iGAS cases that can actually be prevented with antibiotics is much smaller than one might think," Gunnarsson explained.
The researchers identified several reasons for this surprisingly limited effect. Most people who develop a sore throat never visit a health care center at all. Those who do typically wait until the third day of illness or later, by which time they've already passed their most contagious period. Perhaps most striking: 15–25% of iGAS patients are infected by asymptomatic carriers—people who feel completely healthy and thus would never receive antibiotics under any testing regime.
Broadening antibiotic prescribing for sore throats would carry substantial costs. The study warns that a lowered testing threshold would burden primary care systems, crowd out treatment for other patient groups, and expose people unnecessarily to antibiotic side effects. These are not trivial concerns in an era of growing antibiotic resistance.
Rather than chasing prevention through antibiotics, the researchers argue, health care systems should pivot toward faster recognition of genuine warning signs that signal serious infection. In the longer term, they point to a more promising solution: the development of a safe and effective vaccine against streptococci. Such an approach would address the root cause rather than attempting to treat an infection that antibiotics, despite their widespread use, do little to prevent at the population level.