Routine vaccines could be key to combating antibiotic resistance

As vaccination coverage among young children increased, antibiotic use fell sharply, showing how immunization can quietly reshape the fight against drug resistance.

Introduction

Antibiotic use is widespread and often medically unnecessary, contributing to the emergence and growth of antimicrobial resistance (AMR). This represents an unprecedented public health threat that threatens to return the world to the pre-antibiotic era.

During the study period, intensive efforts were made to encourage the correct use of antibiotics. Clinical guidelines for the treatment of otitis media, sinusitis, pneumonia, and throat infections were issued, defining when to prescribe antibiotics, which drugs to use in different situations, and the role of watchful waiting.

Numerous measures have been launched to combat AMR, including the “Essential Elements of Hospital Antibiotic Stewardship Programs” and the “National Action Plan to Combat Antibiotic-Resistant Bacteria” (CDC).

Immunization programs prevent several common infectious diseases in children, for which antibiotics are often prescribed. The reasons for this use include the difficulty in distinguishing bacterial from viral respiratory infections in young children and the prophylactic use of antibiotics to prevent rapid and dangerous deterioration in this vulnerable group.

Previous studies suggest that pneumococcal and influenza vaccines reduce antibiotic use in children. However, these studies have largely focused on individual vaccines, ignoring the synergistic benefits of immunization programs targeting multiple pathogens.

The current study sought to fill this gap by using 20 years of claims data to estimate the true impact of vaccination on antibiotic use in children under five. However, the authors note that the study’s ecological design does not allow for causal inferences.

About the study

The study used the Merative® MarketScan Commercial Claims and Encounters database to collect coverage data for four common childhood vaccines: pneumococcal conjugate vaccine, Haemophilus influenzae type b vaccine, diphtheria-tetanus-pertussis vaccine, and influenza vaccine. The data also included antibiotic prescriptions and antibiotic-treated respiratory infections among children under five years of age over the entire study period.

Based on annual vaccination estimates, children were classified as having received all four vaccines, 1 to 3 vaccines, or none.

Research results

Vaccination trends

The study found that 32.5% of the 6.7 million children under five received all four vaccines in 2004. By 2019, that figure had risen to 67%, with only 2.5% of children remaining unvaccinated.

Use of antibiotics

Broad-spectrum antibiotics accounted for about half of all prescriptions throughout most of the study period. Penicillins accounted for 50% to 61%, while cephalosporins and macrolides accounted for 30% to 45%.

Overall, the number of antibiotic prescriptions has halved over this period, from 1.9 to 1.0 per person per year, with the largest declines seen in 2003–2007 and 2010–2013.

Macrolide antibiotics decreased by 73%, broad-spectrum antibiotics by 57%, and penicillins by 44%.

These results are consistent with previous studies showing, for example, a 6% reduction in antibiotic prescriptions after a 10% increase in influenza vaccination coverage. Macrolides showed the largest reduction because they were frequently prescribed for respiratory infections, especially in patients with penicillin allergies.

Respiratory infections

The most common respiratory infection treated with antibiotics was otitis media. Viral respiratory infections accounted for 30% to 38%, and throat infections accounted for 11% to 15%.

During the study period, the number of respiratory infections treated with antibiotics fell by more than a third, from 2.4 to 1.6 episodes per person per year between 2000 and 2019. Sinusitis fell by 65% and throat infections by 40%.

Stable urinary tract infection rates

Rates of urinary tract infections (UTIs) treated with antibiotics remained relatively stable throughout the study period, except for a modest decline of 5%–24% observed in 2016–2019.

Conclusions and consequences

The slow decline in antibiotic use since 2000 coincided with an increase in vaccination coverage through 2011. The most significant decline in antibiotic use for viral infections occurred after the introduction of the influenza vaccine into the routine childhood immunization schedule in 2004. This highlights the role of prophylactic antibiotic use for influenza, the most common viral respiratory infection.

Thereafter, the main decline was due to antibiotic stewardship programmes, as vaccination rates remained stable until 2017. Small increases in vaccination coverage and ongoing antibiotic stewardship programmes were associated with a sharper decline in antibiotic use.

Thus, increased vaccination coverage and antibiotic stewardship efforts have jointly contributed to this trend. Other factors include improved diagnostics, access to managed care for children, and rising socioeconomic levels of the population, which affect access to medicine and the risk of infections.

Increased use of electronic health records could also help track medical history and antibiotic prescribing practices, providing automated recommendations.

Conclusion

These results indicate a dramatic decline in antibiotic use among young children in the United States, coinciding with an increase in vaccination coverage. Thus, immunization programs have a significant public health impact beyond vaccine-preventable diseases.

But the authors caution that the study cannot prove that vaccination alone caused the reduction in antibiotic use. Future studies should include data on Medicaid-insured and uninsured children, who are less likely to be vaccinated, and examine the effects of different combinations of vaccines.

"These findings highlight the potential policy implications of integrating vaccination programmes into antibiotic stewardship efforts to reduce unnecessary antibiotic use, which will ultimately support public health efforts to combat antibiotic resistance," the study concluded.