mRNA Vaccines Found Very Protective
The Annal of Internal Medicine published an Original Research 'SARS-CoV-2 Vaccine Effectiveness in a High-Risk National Population in a Real-World Setting' on July 20, 2021.
This study found 'currently used (mRNA) vaccines against SARS-CoV-2 virus infection are highly effective (96%+) in preventing confirmed infection in a high-risk population in a real-world setting.
These researchers stated, 'veterans are at particularly high risk given their older age and greater burden of comorbidities compared with the general population, and the high level of vaccine effectiveness observed is therefore reassuring.'
Although these 2 studies had different designs and assessed different populations, the remarkably similar results provide further reassurance of the effectiveness of the vaccines in preventing infection in various real-world settings.
Vaccine effectiveness was 97.5% in persons aged 70 years or older and 96.4% among those younger than 70.
Although this difference was statistically significant, the numerical similarity implies similarly high rates of effectiveness. Thus, slightly higher effectiveness in older persons may be related to lower mobility and a lower likelihood of exposure to infection.
'Although we clearly show the effectiveness of the current vaccines in preventing infection, we did not assess their effectiveness in preventing severe disease and death. A cohort design is better suited to answer this question, as shown by the aforementioned study in Israel. Further studies are warranted to confirm this, although limited data from other health care systems suggest a high level of effectiveness in preventing these serious outcomes,' said these researchers.
Strengths of our study include the large national study population at high risk for infection and the use of the widely accepted test-negative case-control design. However, several limitations must be acknowledged, including a predominantly male population and a lack of data on disease severity and mortality.
Finally, they determined vaccine effectiveness over a relatively short period, and longer follow-up may be needed to determine long-term effectiveness.
In conclusion, the SARS-CoV-2 vaccines currently used in the VA health care system provided a high level of protection against confirmed virus infection, said these researchers.