Effectiveness of Messenger RNA Coronavirus Disease 2019 Vaccines Against Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infections During the Delta Variant Epidemic in Japan: Vaccine Effectiveness Real-time Surveillance for SARS-CoV-2 (VERSUS)

  1. Haruka Maeda
  2. Nobuo Saito
  3. Ataru Igarashi
  4. Masayuki Ishida
  5. Kazuya Suami
  6. Ai Yagiuchi
  7. Yuya Kimura
  8. Masaru Komino
  9. Hiromi Arai
  10. Toru Morikawa
  11. Iori Motohashi
  12. Rei Miyazawa
  13. Tetsu Moriyama
  14. Hiroshi Kamura
  15. Mayumi Terada
  16. Osamu Kuwamitsu
  17. Tomoichiro Hayakawa
  18. Eiichiro Sando
  19. Yasuji Ohara
  20. Osamu Teshigahara
  21. Motoi Suzuki
  22. Konosuke Morimoto

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Abstract

Background

Although high vaccine effectiveness of messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccines has been reported in studies in several countries, data are limited from Asian countries, especially against the Delta (B.1.617.2) variant.

Methods

We conducted a multicenter test-negative case-control study in patients aged ≥16 years visiting hospitals or clinics with signs or symptoms consistent with COVID-19 from 1 July to 30 September 2021, when the Delta variant was dominant (≥90% of SARS-CoV-2 infections) nationwide in Japan. Vaccine effectiveness of BNT162b2 or mRNA-1273 against symptomatic SARS-CoV-2 infections was evaluated. Waning immunity among patients aged 16–64 years was also assessed.

Results

We enrolled 1936 patients, including 396 test-positive cases and 1540 test-negative controls for SARS-CoV-2. The median age was 49 years, 53.4% were male, and 34.0% had underlying medical conditions. Full vaccination (receiving 2 doses ≥14 days before symptom onset) was received by 6.6% of cases and 38.8% of controls. Vaccine effectiveness of full vaccination against symptomatic SARS-CoV-2 infections was 88.7% (95% confidence interval [CI], 78.8%–93.9%) among patients aged 16–64 years and 90.3% (95% CI, 73.6%–96.4%) among patients aged ≥65 years. Among patients aged 16–64 years, vaccine effectiveness was 91.8% (95% CI, 80.3%–96.6%) within 1–3 months after full vaccination, and 86.4% (95% CI, 56.9%–95.7%) within 4–6 months.

Conclusions

mRNA COVID-19 vaccines had high effectiveness against symptomatic SARS-CoV-2 infections in Japan during July–September 2021, when the Delta variant was dominant nationwide.

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  1. Version published to 10.1093/cid/ciac292
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    SciScore for 10.1101/2022.01.17.22269394: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: All analysis was performed using Stata version 16.0 (Stata Corp., College Station, Texas, USA) Ethics: This study was approved by the Institutional Review Board (IRB) at the Institute of Tropical Medicine, Nagasaki University (approval no. 210225257) and the study sites.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Demographic and clinical information was collected from medical charts and recorded on an electronic database using REDCap [23].
    REDCap
    suggested: (REDCap, RRID:SCR_003445)

    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:
    This study had several limitations. First, the sample size was limited to 13 study sites in nine prefectures between July 1, 2021, and September 30, 2021. Second, recall bias could occur in vaccination histories. In Japan, medical professionals working at medical institutions are not allowed to access governmental vaccination records, and vaccination histories included in this analysis were obtained through interviews with patients or their family members. To strengthen our results, we conducted several sensitivity analyses (Supplementary Table 1). Vaccine effectiveness obtained from sensitivity analyses was similar to the primary analysis, and we considered our results robust. Third, since we didn’t conduct SARS-CoV-2 genome sequencing for test-positive patients, it was impossible to obtain an accurate estimation of vaccine effectiveness of mRNA COVID-19 vaccines against the Delta variant. Fourth, we included test methods other than PCR when determining cases and controls because in Japan, test methods such as LAMP and antigen quantification have been used as commonly as PCR. Since these tests have acceptable levels of sensitivity and specificity, we thought it reasonable to include these test methods. In conclusion, mRNA COVID-19 vaccines were highly effective for preventing symptomatic SARS-CoV-2 infections in Japan from July to September 2021, when the Delta variant circulated nationwide. Thus, vaccine effectiveness of mRNA COVID-19 vaccines remained high in Japan despite...

    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.

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  3. Version published to 10.1101/2022.01.17.22269394v1 on medRxiv