December 4, 2022

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BNT162b2 mRNA COVID-19 vaccine has high protection for medical staff

NEJM: BNT162b2 mRNA COVID-19 vaccine has high protection for medical staff

 

 

BNT162b2 mRNA COVID-19 vaccine has high protection for medical staff.  On July 1, 2021, the New England Journal of Medicine published a real-world study conducted in 6 states in the United States.

The results of the study showed that two complete doses of mRNA vaccines (BNT162b2 and mRNA-1273) can effectively prevent up to 91% of asymptomatic infections, and in breakthrough cases (infections after vaccination), those who have completed partial or complete vaccination The viral load was reduced by 40%, the duration of symptoms was shortened by 6.4 days, the time spent in bed was reduced by 2.3 days, and the risk of fever symptoms was reduced by 58% for those who completed some vaccinations.

The study included 3975 medical staff (53%), emergency personnel (21%), other essential and front-line workers (26%). Approximately 62% were female subjects, 72% were 18-49 years old, and 69% of subjects had no chronic diseases. As of April 10, 2021, BNT162b2 vaccine accounted for 67% and mRNA-1273 vaccine accounted for 33% of vaccinations.

During the study period (2020.12.14-2021.4.10), regardless of whether the subject has symptoms of COVID-19, a continuous nasal swab nucleic acid test for up to 17 weeks will be performed; once COVID-19-related symptoms appear, additional samples will be collected Nasal swabs and saliva samples. A total of 204 (5%) subjects developed COVID-19 infections, of which 5 had completed full vaccination (≥14 days after the second dose), and 11 had completed partial vaccination (≥14 days after the first dose, and after the second dose <14 days), 156 people were not vaccinated; another 32 people <14 days after the first dose of vaccination were not included in the analysis because they could not determine the vaccination status. The main results of the study are as follows:

1. The analysis results after model adjustment show that the effective rate of completing two complete doses of mRNA vaccination to prevent asymptomatic infection is 91%, and the effective rate of completing partial vaccination to prevent asymptomatic infection is 81%. This result is similar to the high protection rate of the BNT162b2 vaccine in its phase 3 clinical trial and the data from the real-world study of British medical staff.

2. The analysis of breakthrough cases shows that compared with those who have not been vaccinated, those who have completed partial or complete mRNA vaccination have a 40% reduction in viral RNA load in their bodies. The average viral load of the former is 3.8 log10 copies/mL, and the latter is 2.3 log10 copies/mL.

3. The analysis of the infection time showed that among the vaccinated infected persons (75%), the RNA viral load was tested for only 1 week, while among the unvaccinated infected persons (72%), the testing time exceeded 1 week. week. The results showed that people who were infected after vaccination had shorter infection time, and the risk of nucleic acid positive for more than 1 week was reduced by 66%.

4. The results of the analysis of the severity and duration of the disease of the infected person showed that: the vaccinated person has fever symptoms [the febrile symptoms related to COVID-19 are defined as the risk of fever, fever, chills, or measured body temperature higher than 38°C] Reduced by 58%, the number of days sick in bed was reduced by 2.3 days, and the duration of symptoms was reduced by 6.4 days.

In summary, for people at high risk of exposure to the new coronavirus (such as medical staff, emergency personnel, other essential and front-line workers), the study has important value for the high protection rate of asymptomatic infection prevention, and can not only reduce vaccinators It also reduces the risk of virus transmission. At the same time, results such as reduced viral load and symptom relief in breakthrough infections suggest that it can effectively control the rapid spread of the virus and reduce the infectivity of breakthrough cases.

 

(source:internet, reference only)


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