OpenSAFELY studies show the effectiveness of Pfizer COVID booster doses

In a recent study posted on medRxiv* Preprint server, researchers Pfizer in 7 million UK (UK) adults eligible for booster shots between September 16th and December 16th, 2021-BioNTech BNT162b2 Coronavirus Disease 2019 (COVID-19) The efficacy of the vaccine was evaluated.

study: Efficacy of BNT162b2 Booster Dose in the United Kingdom: Observational Study with OpenSAFELY-TPP.. Image Credit: Jo Panuwat D / Shutterstock

Background

Under the national COVID-19 vaccination program, the UK initially prioritized receiving booster shots in September 2021 before high-risk populations became available to the general adult population. However, after the emergence of the Variant of Concern (VOC) Omicron for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), booster availability decreased to 3 months on December 8, 2021. The individual received a second dose of COVID-19 vaccine.

About research

In this study, researchers estimated the efficacy of booster shots of the BNT162b2 vaccine in adults who received two vaccines between September 16 and December 16, 2021. The team used data from the OpenSAFELY-TPP database for research analysis. The database contained information on 40% of UK primary care practices linked to national coronavirus surveillance, hospitals, and death registration data. Study follow-up will continue for 10 weeks or December 31, 2021, and researchers will compare each booster recipient to the corresponding non-boostered control subject based on booster priorities and previous vaccination status. Did.

The team assigned matching controls to each study participant based on the National Health Service (NHS) region, study start date, vaccine brand, and date of second vaccination. A Cox regression model tuned for these factors to estimate the hazard ratio (HR). The 1-HR, expressed as a percentage, indicates the BNT162b2 booster effect. HR estimates were compared on days 1-28 and 29-70, overall and individually, with those who were not boosted. In addition, the teams were on days 1-7, 8-14, 15-28, 29-42, and 43-70. Results were available: positive SARS-CoV-2 test, COVID-19-related deaths, COVID-19 hospitalization, and COVID-19-independent deaths.

Survey results

The study population consisted of 6,990,219 individuals who matched as controls and then rematched in the booster group. As expected, the proportion of people with concordance factors and pre-existing morbidity was similar between study groups. The standardized mean difference between the two groups was consistently less than 0.1, but subjects in the control group had more learning disabilities, less frequent SARS-CoV-2 tests, and a rate of severe mental illness and deprivation. Was expensive. Screening for a 23,151,145 person-week follow-up resulted in 123,378 SARS-CoV-2 positive tests, 3,672 COVID-19 hospitalizations, 588 COVID-19 deaths, and 6,990 non-COVID-19 deaths. ..

Boosted individuals showed an abnormal increase in the overall incidence of the positive SARS-CoV-2 test approximately 7 days after receiving the booster shot. However, they did not show a similar pattern for other serious COVID-19 results. In addition, differences in the overall incidence of positive SARS-CoV-2 tests between study groups were apparent in the first few days.

Therefore, the 10-week risk of a positive SARS-CoV-2 test in the boosted and non-boosted groups is 47.3 and 84.0 per 1000, respectively, which corresponds to a risk difference of 36.8 per 1000. Deaths from COVID-19 and non-COVID-19 were 3.6, 1, and 8.1, respectively.

The (overall) booster effects on days 1-7 were 50.7%, 80.1%, and 88.5% for SARS-CoV-2 test positive, COVID-19 hospitalization, COVID-19 death, and non-COVID-19 death. , And 80.3%. .. In addition, the booster effect on all COVID-19 results was generally lower between 1 and 28 days and between 29 and 70 days. Within a shorter period of time, the booster effect on the positive SARS-CoV-2 test appeared to diminish from about 6 weeks after the booster. Vaccination, 68.2% vs. 45.3% between 15-28 and 43-70 days.

Conclusion

Overall, booster shots of BNT162b2 reduced the rate of SARS-CoV-2 positivity by about 50% in the first 10 weeks after booster administration. In addition, booster shots reduced the rates of COVID-19 hospitalization, COVID-19 deaths, and non-COVID-19 deaths. More importantly, the booster effect remained similar for all severe COVID-19 results, regardless of the brand of vaccine used for primary vaccination and previous infections.

Conversely, the estimated booster dose was lower in the under 65 and clinically vulnerable populations. The authors emphasized the need for long-term monitoring of the efficacy of booster vaccines, as current studies show evidence of a reduced booster effect on the positive SARS-CoV-2 test.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they have not been peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.