Effectiveness of Pfizer-BioNTech Vaccine Against COVID-19 Associated Hospitalizations among Lebanese Adults ≥75 years- Lebanon, April-May 2021

  1. Zeina Farah
  2. Nadine Haddad
  3. Hala Abou El Naja
  4. Majd Saleh
  5. Pamela Mrad
  6. Nada Ghosn

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Abstract

Introduction

In Lebanon, the nationwide vaccination against COVID-19 was launched in February-2021 using Pfizer-BioNTech vaccine and prioritizing elderly, persons with comorbidities and healthcare workers. Our study aims to estimate the post-introduction vaccine effectiveness (VE) of Pfizer-BioNTech in preventing COVID-19 hospitalization among ≥75 years in Lebanon.

Methods

A case-control study design was used. Cases were Lebanese, ≥75 years and hospitalized with positive PCR result during April-May 2021. Cases were randomly selected from the COVID-19 database of the Epidemiological Surveillance Unit(ESU) at the Ministry of Public Health(MOPH). Each case was matched by age and locality to 2 controls. Controls were hospitalized, non-COVID-19 patients with negative PCR result, randomly selected from the MOPH hospital admission database. VE was calculated for fully and partially vaccinated, using multivariate conditional logistic regression analyses.

Results

345 cases and 814 controls were recruited. Half were females, with a mean age of 83 years. 14 cases(5%) and 143 controls(22%) were fully vaccinated. Bivariate analysis showed significant association with: gender, month of confirmation/admission, general health, chronic medical conditions, main income source and living arrangement. After adjusting for month of admission and gender, multivariate analysis yielded a VE of 82% (95%CI = 69%-90%) against COVID-19 associated hospitalization for those fully vaccinated and 53% (95%CI = 23%-71%) for those partially vaccinated (≥14 days of first or within 14 days of second dose).

Conclusions

Our study showed that Pfizer-BioNTech vaccine is effective in reducing risk for COVID-19– associated hospitalization in Lebanese elderly(≥75 years). Additional studies are warranted to explore vaccine effectiveness in reducing hospitalization in younger age groups, as well as in reducing covid-19 infections.

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  1. ScreenIT

    SciScore for 10.1101/2022.01.19.22269514: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: Ethical approval: The study was approved by the Institutional Review board of the Rafik Hariri University Hospital.
    Consent: Informed consent was obtained from study subjects prior to participation.
    Sex as a biological variablenot detected.
    RandomizationA random sample of 742 cases was drawn from the selected sampling frame and contacted to verify whether they meet our study inclusion criteria.
    Blindingnot detected.
    Power AnalysisOur sample size was calculated using the precision method with 90% vaccine effectiveness for full vaccination and 40% vaccine coverage, a ±5% precision and a type 1 error of 0.05.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Limitations: The study findings are subject to some limitations. First, The MOPH admission database, from which controls were sampled, is not inclusive of the total target population as it covers hospitalization of citizens who are uninsured and who usually belong to the most deprived segments of the population, such as seasonal workers, farmers, retired and unemployed persons, thus on average an older and poorer population (9). Additionally, vaccine effectiveness estimates might be confounded by certain unmeasured behaviors like adherence to non-pharmaceutical interventions, including mask use or recent attendance of gatherings in addition to some variables like socioeconomic status and prior SARS-COV-2 infection. This might have affected our results as uncontrolled confounders might lead to differences in vaccine uptake, exposure to infection, and development of severe disease implications.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  2. Version published to 10.1101/2022.01.19.22269514v1 on medRxiv