Sumary of Nationwide Swedish study strengthens evidence for a third booster COVID vaccine dose:
- Vaccines are effective against coronavirus disease 2019 (COVID-19) and protect from the risk of infection and severe illness and death.
- However, breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections have raised concerns about waning vaccine effectiveness.
- Several studies indicate that vaccines protect against severe illness up to 6 months after vaccination.
- Further observational studies have evaluated high real-world effectiveness.
- However, protection against severe illness appears to be maintained.
- The evidence is limited and inconsistent because of evaluations of different vaccines that may have variable long-lasting effects, a low proportion of old participants in the studies, and varying and relatively short follow-up times.
- Related StoriesAnother cohort formed using less strict matching criteria resulted in 3,966,630 individuals forming 1,983,315 pairs.
- Data on cases of symptomatic infection and severe COVID-19, i.