An observational study of the association between COVID-19 vaccination rates and entry into the Australian ‘Million Dollar Vax’ competition

Abstract

Objectives

To examine the association between financial incentives from entry into a vaccine competition with the probability of vaccination for COVID-19.

Design

A cross-sectional study with adjustment for covariates using logistic regression

Setting

October and November 2021, Australia.

Participants

2,375 respondents of the Taking the Pulse of the Nation Survey

Primary and secondary outcome measures

The proportion of respondents who had any vaccination, a first dose only, or second dose after the competition opened.

Results

Those who entered the competition were 2.27 (95% CI 1.73 to 2.99) times more likely to be vaccinated after the competition opened on October 1 ^st than those who did not enter—an increase in the probability of having any dose of 0.16 (95 % CI 0.10 to 0.21) percentage points. This increase was mostly driven by those receiving second doses. Entrants were 2.39 (95% CI 1.80 to 3.17) times more likely to receive their second dose after the competition opened.

Conclusions

Those who entered the Million Dollar Vax competition were more likely to receive a vaccination after the competition opened compared to those who did not enter the competition, with this effect dominated by those receiving second doses.

Strengths and limitations of this study

We use a nationally representative sample of individual self-reported vaccination status and timings.
We distinguish between the association between competition entry and first and second doses.
We adjust for a rich set of individual characteristics associated with vaccination status, and examine the factors influencing competition entry
The strong association for second dose vaccinations may reflect some individuals who had already scheduled their second dose after the competition opened, potentially leading to an overestimate of the association.

SciScore for 10.1101/2022.03.02.22271734: (What is this?)

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

Table 1: Rigor

Ethics	not detected.
Sex as a biological variable	Each wave includes 600 men and 600 women, and the shares of respondents for each state and ACT are proportional to the population of that state or territory.
Randomization	not detected.
Blinding	not detected.
Power Analysis	not detected.

Table 2: Resources

No key resources detected.

Results from OddPub: Thank you for sharing your data.

Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

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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