Covid cases in the UK sit at roughly 7.47 million infection cases and 135,000 deaths. The hospital admission rate of COVID-19-confirmed patients in England remained relatively stable and was at 7.29 per 100,000 people in the week ending 12 September 2021. Trends in hospital admissions varied across age groups and the English regions. A Dutch study delved into vaccine effectiveness in helping to reduce hospitalisations.
From April 4, 2021, to August 29, 2021, researchers enrolled 15,571 people hospitalised for COVID-19 infection into the study.
In the Netherlands, Alpha was the dominant variant from April 4, 2021, to May 29, 2021.
This position was taken over by Delta, which circulated from July 4, 2021, to August 29, 2021 — the end of the study period.
Researchers defined someone as being fully vaccinated 14 days after the second dose or 28 days after the first Johnson & Johnson dose.
Only a very small amount of the study participants was fully vaccinated, making it difficult to assess how the type of vaccine affected vaccine effectiveness.
Although the researchers suggest the lower vaccine effectiveness from Spikevax may have been because the vaccine was primarily given to patients who were already at high risk for severe COVID-19 disease.
The researchers gathered data on COVID-19 vaccination status did not include patient information on comorbidities.
Having a pre-existing health condition increases your risk of developing severe infection and could also explain the low vaccine effectiveness from Spikevax since it was administered in high-priority groups.
The registry included patients who did not enter the hospital for COVID-19 infection but rather people who later tested positive.
The researchers suggest this could cause a bias in vaccine effectiveness estimates because it affects the severity of infection in some patients. Although, they note that misclassification is more likely to occur with vaccinated patients.