Saturday, December 2, 2023

New vaccine against Strep A could drastically cut antibiotic use for sore throats, study suggests

A new study published in the journal eBioMedicine predicts whether the widespread introduction of a vaccine against group A Streptococcus (Strep A) could reduce the use of antibiotics for sore throat.

Study: Antibiotic consumption for sore throat and the potential effect of a vaccine against group A Streptococcus: a systematic review and modelling study. Image Credit: goodluz /


Most sore throats result from viral infections; however, Strep A is the leading cause of acute bacterial pharyngitis or tonsillitis. Clinically, viral and bacterial sore throats are associated with similar symptoms. It is both expensive and time-consuming to differentiate between viral and bacterial infections through diagnostic tests, thus limiting their use in poorer settings.

In some cases, these infections may lead to severe complications, including streptococcal toxic shock syndrome (TSS), acute rheumatic fever culminating in rheumatic heart disease, and post-streptococcal glomerulonephritis. As a result, precautionary antibiotics against Strep A are often prescribed, with this being the second- and third-ranked cause for prescribing antibiotics in Europe and the United States, respectively.

The development of a Strep A vaccine has been proposed by the World Health Organisation (WHO) as a global priority.”

What did the study show?

The current study estimates current antibiotic consumption rates for sore throat in absolute and relative terms, identifies the antibiotics prescribed for this indication, and estimates the reduction that could potentially follow the rollout of Strep A vaccines.

The researchers analyzed about 100 studies on antibiotic usage for sore throat from 38 countries. On average, five courses of antibiotics were prescribed for sore throat for every 100 populations annually.

Moreover, one in 20 antibiotic courses was used worldwide, with this use rate reaching up to one in seven in some countries. The average rate among young people was about 13, while for adults, it was six for every 100 populations yearly.

Based on 2020 estimates for empiric prescription rates, an estimated 37 million antibiotic courses were prescribed annually to treat sore throats. In 2020, about nine million children between the ages of five and 14 received antibiotics for sore throat. Of these, about 50% were in response to diagnosed Strep A infections, which cause approximately 600 million cases of sore throat yearly. 

The studies on prescription rates were primarily performed in high-income countries (HIC), the most common of which included the U.S., the United Kingdom, and two Scandinavian countries. The countries of origin of these studies comprised about one-tenth of the world’s all-ages population and half of the population of high-income countries.

These countries comprised about 5% of the world’s children compared to over half of children in HIC and only 1% of middle-income countries. Low-income countries (LIC) were not represented.

Penicillins were most commonly prescribed for sore throat, with macrolides, lincosamides, and other beta-lactams also commonly prescribed. Amoxicillin-clavulanate was most frequently referenced among antibiotics not used according to current country-specific guidelines.

Antibiotics are often prescribed due to patient pressure, expectations, or the fear of losing or spoiling a good patient-practitioner relationship. However, antibiotic prescribing to patients who are unlikely to benefit can lead to significant health effects.

Suppose an effective vaccine was introduced against Strep A with approximately 10 years of protection and achieved 80% coverage. In that case, it is estimated that it would prevent almost three million antibiotic courses prescribed for sore throats in children between five and 14 years of age, the group with maximum usage rates. This estimate accounts for over 30% of current prescriptions, assuming that providers will still prescribe at the current rate when presented with sore throats.

Vaccination could also reduce antibiotic prescriptions for sore throat by preventing a significant proportion of Strep A infections. This would reduce antibiotic prescriptions for sore throat by at least 7.5 million annually.

Vaccines could reduce antibiotic prescriptions by over 40% with increased coverage and efficacy. HICs would significantly reduce antibiotic prescribing for sore throats, especially in the Netherlands, where prescribing rates are low.

What are the implications?

It remains difficult to confirm the global use of antibiotics for sore throat and how much of these antibiotics are used to treat Strep A infections.

Notably, no studies were performed in low- to middle-income countries (LMIC) despite the relatively higher rates of severe post-Strep A complications in these nations. Thus, exploring antimicrobial use for sore throat in these countries is crucial, as this may be a potential cause of antimicrobial resistance.

The current study does not account for herd immunity against Strep A or the possibility of a lower need for global antibiotic use for sore throats. The waning of vaccine efficacy over time was also not modeled.

Nevertheless, the study findings indicate that introducing an effective vaccine against Strep A could reduce antibiotic prescriptions for sore throat by at least 33%. The extent of this reduction would vary with alterations in prescribing behaviors by healthcare providers and changes in antibiotic consumption.

Thus, the impact of vaccination on antibiotic prescribing rates is as high or higher than the effect of improved vaccine parameters, including vaccine coverage, efficacy, or duration of protection. 

Journal reference:

  • Miller, K. M., Barnett, T. C., Cadarette, D., et al. (2023). Antibiotic consumption for sore throat and the potential effect of a vaccine against group A Streptococcus: a systematic review and modelling study. eBioMedicine. doi:10.1016/j.ebiom.2023.104864.

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