syringe and vials on a mask

A recent study published in the New England Journal of Medicine reported on data from 187 hospitals in the United States, where individuals treated with 2-dose COVID-19 vaccines were prevented from hospitalizations, emergency visits to hospitals, or even intensive care admissions as a result of virus exposure. Electronic health records (EHRs) providing real-world evidence suggested that the vaccines were successful in providing high levels of protection for populations affected by the virus, including the elderly.

Data was collected for patients admitted in the ICU as well as from hospital emergency visits and urgent care clinics. A total of 45,000 COVID-19 encounters were considered in this study.

Data analysis suggested that 2-dose mRNA vaccination of either Moderna or Pfizer vaccines were effective at preventing hospitalizations, emergency visits, and ICU admissions:

  • 89% effective at preventing hospitalizations from COVID-19
  • 91% effective at preventing emergency or urgent care visits
  • 90% effective at preventing ICU admissions

These efficacies were slightly lower in individuals with only 1 dose of the respective vaccines.

The authors commented, ”This study confirms that these vaccines are highly effective.” They also said, ”they offer significant protections for people older than 85, people with chronic medical conditions, as well as in Black and Hispanic adults. All are groups who have been hit particularly hard by this disease. We hope this information will convince more people to get vaccinated to protect not only themselves but their community,”

This study was the first of its kind to look at the effectiveness of the single-dose Johnson and Johnson vaccine. Data suggested that it was 73% effective against emergency care and urgent care visits and 68% effective against hospitalizations. However, it should be noted that this data was obtained with a smaller sample size and in order to check the precision of these estimates, more data would be needed.

The authors also said that this study involving real-world statistics correlated with the clinical trials and provide more confidence in the vaccines.


  • Thompson, M.G. et al., (2021). Effectiveness of Covid-19 Vaccines in Ambulatory and Inpatient Care settings. New England Journal of Medicine.
  • Image by ronstik from Pixabay 
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