December 5, 2023

Study Finds Gradual Increase in COVID-19 Infection Risk After Second Vaccine Dose

The research study was brought out by the Research Institute of Leumit Health Services in Israel. Israel was one of the first countries to roll out a large scale covid-19 vaccination campaign in December 2020, however which has seen a revival of infections since June 2021.
The findings confirm that the Pfizer-BioNTech vaccine provided exceptional protection in the preliminary weeks after vaccination, but suggest that protection wanes for some people with time.
Throughout the world, big scale covid-19 vaccination campaigns are assisting to control the spread of the virus, however even in countries with high vaccination rates, breakthrough infections can happen, which researchers think is due to a gradual loss of resistance with time.
Taking a look at the time elapsed considering that vaccination and threat of infection could supply important ideas about the need for a third injection and its favored timing.
To do this, the scientists analyzed electronic health records for 80,057 grownups (typical age 44 years) who got a PCR test a minimum of three weeks after their 2nd injection, and had no proof of previous covid-19 infection.
Of these 80,057 participants, 7,973 (9.6%) had a positive test result. These people were then matched to unfavorable controls of the very same age and ethnic group who were evaluated in the very same week.
The rate of positive outcomes increased with time elapsed considering that a 2nd dose. Throughout all age groups 1.3% of participants evaluated favorable 21-89 days after a 2nd dosage, but this increased to 2.4% after 90-119 days; 4.6% after 120-149 days; 10.3% after 150-179 days; and 15.5% after 180 days or more.
And after taking account of other potentially influential factors, the scientists found a substantially increased risk of infection with time expired because a 2nd dosage.
Compared to the initial 90 days after a 2nd dosage, the danger of infection throughout any age groups was 2.37-fold higher after 90-119 days; 2.66-fold higher after 120-149 days; 2.82-fold greater after 150-179 days; and 2.82-fold greater after 180 days or more.
The scientists acknowledge that interpretation of their findings is restricted by the observational style, and they can not eliminate the possibility that other unmeasured factors such as family size, population density, or infection pressure might have had an effect.
This was a large research study of people who all got the same vaccine, and the researchers were able to carry out detailed analysis of the data, suggesting that the outcomes are robust.
As such, they conclude that in individuals who got 2 doses of the Pfizer-BioNTech vaccine, defense appeared to decrease in time, and the risk of breakthrough infection increased progressively compared with the protection provided during the preliminary 90 days.
The results suggest that factor to consider of a 3rd vaccine dose may be warranted, they include.
Recommendation: “Elapsed time since BNT162b2 vaccine and threat of SARS-CoV-2 infection: test negative style research study” by Ariel Israel, Eugene Merzon, Alejandro A Schäffer, Yotam Shenhar, Ilan Green, Avivit Golan-Cohen, Eytan Ruppin, Eli Magen and Shlomo Vinker, 25 November 2021, The BMJ.DOI: 10.1136/ bmj-2021-067873.

Results validate that protection wanes with time and recommend a third (booster) dose may be warranted
A study published by The BMJ discovers a progressive boost in the risk of covid-19 infection from 90 days after receiving a second dosage of the Pfizer-BioNTech vaccine.