Long-term protection and high efficacy of a bivalent BA.1 booster confirmed in the elderly

A recent study published in medrex sib* The preprint server estimates the duration of protection from monovalent vaccination and efficacy of Bivalent vaccine booster for hospitalization due to coronavirus disease 2019 (COVID-19).

study: Long-term protective duration of ancestral strain monovalent vaccine and efficacy of bivalent BA.1 booster for COVID-19 hospitalization during BA.5, BQ.1, CH.1.1. and his XBB.1.5 distribution in England. Image Credit: GroundPicture/Shutterstock.com

*Important Notices: medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.

Background

A monovalent vaccine based on the ancestral strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is effective against severe COVID-19.

However, the emergence of mutants with immune evasion properties has weakened vaccine efficacy and durability of protection. Several countries have implemented frequent booster programs to protect vulnerable (sub)populations.

Bivalent vaccine targeting ancestry and omicron spike protein being developed. Studies have shown that a bivalent vaccine enhances neutralization capacity against SARS-CoV-2 Omicron BA.2.75, BA.4, and BA.5.

About research

In this study, researchers evaluated the long-term protection of a monovalent vaccine and the efficacy of a bivalent vaccine against COVID-19-related hospitalizations in the UK. They implemented a test-negative case-control design.

The study periods are from June 13, 2022 to December 25, 2022 and from September 5, 2022 to February 5, 2023, depending on the efficacy of monovalent and bivalent booster vaccination, respectively. Evaluated protection period.

The date of the most recent positive test during the study period was identified. Non-Omicron cases were excluded. COVID-19 laboratory data were linked to the National Immunization Management System (NIMS).

Data on vaccination, sex, age, ethnicity, risk group status, immunosuppression, clinically highly vulnerable status, and social/health worker status were accessed from NIMS.

Hospitalizations for acute respiratory illness were identified from secondary use services and linked to test data.

SARS-CoV-2 testing was limited to hospitalizations requiring supplemental oxygen, intensive care, or mechanical ventilation to estimate vaccine efficacy for severe disease outcomes.

Multivariate logistic regression used test outcome and vaccination as primary variables of outcome and interest, respectively. Incremental vaccine efficacy (iVE) of the 4th vaccination was estimated compared to the last third of those aged 75 years or older who received at least 6 months prior to the sample date .

The iVE of the bivalent booster was estimated in people who had received at least two doses of the vaccine by 5 September 2022 and who had been vaccinated 6 months prior to the study date.

findings

The authors identified 63,251 tests from hospitalized patients aged 18 years and older. This includes her 19,841 cases who did not receive a bivalent booster.

The two-dose (monovalent) absolute vaccine efficacy (aVE) was 68.8% after 3–5 months and decreased to 22.2% after 15 months in the 18–64 year old group. Mean values ​​for 3 doses were 46.4% after 3-5 months and 18.3% after 12-15 months.

In those aged 65 years and older, the two-dose (monovalent) aVE was 71.7% at 3-5 months and 40.2% at 15 months after the second vaccination. The aVE after the third dose was 65.3% after 3-5 months and 52.3% after 12-14 months.

aVE for critical illness was 39.1% 15 months after the second dose and 49.3% 12-14 months after the third dose.

In addition, the iVE of 4th dose versus 3rd dose in individuals aged 75 years and older peaked at 50% and declined to levels similar to protection with 3rd dose.

The team identified 49,062 tests from hospitalized patients aged 50 and older who received bivalent boosters. Of these, 9,954 and he 39,108 were cases and controls, respectively.

Additionally, the iVE of the bivalent booster peaked at 53% after 2-3 weeks and declined to 35.9% after 10 weeks. No significant differences were observed when stratified by manufacturer of bivalent booster vaccines.

iVE for critical illness was 60.9% and 69.3% for the Pfizer and Moderna bivalent vaccines, respectively.

Moreover, iVE of bivalent booster vaccination increased with time from the last dose. There were no significant differences among those who received 2, 3, or 4 he doses before bivalent vaccination. Her bivalent booster iVE over 75 years was 48% after 2-4 weeks.

Conclusion

The study found that monovalent vaccine protection against hospitalization was long-lasting, leveled off about 6 months after the last vaccination, and moderately protected after 15 months. .

A bivalent booster increased protection by approximately 53% compared to a monovalent vaccine.

Taken together, these findings provide evidence that long-term protection against severe disease is conferred even after 3 or more doses of monovalent vaccine, and in those who are not at risk of severe outcome It suggests that no additional vaccinations may be necessary.

In addition, bivalent boosters conferred additional protection on older adults at risk of severe disease.

*Important Notices: medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be taken as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.