  Despite ample supply of COVID-19 vaccines, the proportion of fully vaccinated
individuals remains suboptimal across much of the US. Rapid vaccination of
additional people will prevent new infections among both the unvaccinated and
the vaccinated, thus saving lives. With the rapid rollout of vaccination
efforts this year, the internet has become a dominant source of information
about COVID-19 vaccines, their safety and efficacy, and their availability. We
sought to evaluate whether trends in internet searches related to COVID-19
vaccination - as reflected by Google's Vaccine Search Insights (VSI) index -
could be used as a marker of population-level interest in receiving a
vaccination. We found that between January and August of 2021: 1) Google's
weekly VSI index was associated with the number of new vaccinations
administered in the subsequent three weeks, and 2) the average VSI index in
earlier months was strongly correlated (up to r = 0.89) with vaccination rates
many months later. Given these results, we illustrate an approach by which data
on search interest may be combined with other available data to inform local
public health outreach and vaccination efforts. These results suggest that the
VSI index may be useful as a leading indicator of population-level interest in
or intent to obtain a COVID-19 vaccine, especially early in the vaccine
deployment efforts. These results may be relevant to current efforts to
administer COVID-19 vaccines to unvaccinated individuals, to newly eligible
children, and to those eligible to receive a booster shot. More broadly, these
results highlight the opportunities for anonymized and aggregated internet
search data, available in near real-time, to inform the response to public
health emergencies.
