The study confirms the launch of the COVID-19 vaccine, which is reducing the incidence of disease in the United States

By comparing the vaccination rates in 580 counties in the USA with the corresponding incidence rates for coronavirus diseases (COVID-19), a current study, which is currently available on the medRxiv * preprint server, has shown that the cumulative vaccination rates at the county level are significant have been associated with a simultaneous decrease in the incidence of COVID-19.

With mass vaccination efforts spreading around the world to contain the COVID-19 pandemic, there is an urgent need to assess in real time how vaccination rates (but also other important factors) are actually spreading in the community and localized outbreaks influence.

In early March 2021, more than 51 million people in the US were given at least one dose of COVID-19 vaccine, including over 26 million people fully vaccinated with both doses of Pfizer / BioNTech (BNT162b2) or Moderna (mRNA-1273) vaccines.

While Phase III clinical trials for the above two FDA-cleared mRNA vaccines have been shown to lower the risk of symptomatic COVID-19, their real efficacy and safety has recently been confirmed by the use of context-rich electronic health records across America and Israeli health systems.

However, the impact of vaccination on the transmission of severe coronavirus 2 with acute respiratory syndrome (SARS-CoV-2) in the community has yet to be characterized, which is what Dr. Arjun Puranik led a research group from nference in Cambridge, Massachusetts to investigate this very problem.

Curate data and compare rates

To conduct a full and real-world analysis of the exact effects of vaccines on COVID-19 incidence in the US, these researchers first received polymerase chain reaction (PCR) test data at the county level, as well as temporal and cumulative county-level vaccination data.

Then they focused on the correlation between two metrics: the cumulative vaccination rate at the county level (this is the percentage of the county population who received at least one dose) and the change in COVID-19 incidence rate from December to March (i.e. the difference) in 7-day incidence rates between December 1, 2020 and March 1, 2021).

In addition, by March 1, 2021, the researchers conducted a separate manual curation of cumulative vaccination rates in 1,408 counties from 28 states. Some of the analyzes in this document have also taken into account a time lag (or a one-month “gap period”).

Association between mass vaccination and COVID-19 incidence.  (A) US district map showing 7-day SARS-CoV-2 PCR positivity rates (PPR) for December 1, 2020 prior to the start of the FDA-approved COVID-19 vaccine rollout (left panel) and 7-day PPR for March 1 2021 after phase 1a of the mRNA vaccination between December 2020 and February 2021. The color bar varies from green (low PPR) to red (high PPR).

Association between mass vaccination and COVID-19 incidence. (A) US district map showing 7-day SARS-CoV-2 PCR positivity rates (PPR) for December 1, 2020 prior to the start of the FDA-approved COVID-19 vaccine rollout (left panel) and 7-day PPR for March 1 2021 after phase 1a of the mRNA vaccination between December 2020 and February 2021. The color bar varies from green (low PPR) to red (high PPR).

A decrease in COVID-19 incidence

This study has shown that cumulative county-level vaccination rates through March 1, 2021 are significantly associated with a consistent decrease in COVID-19 incidence, with stronger negative correlations in counties in the Midwest and counties in the South.

In addition, all of the regions studied show significant negative correlations between the cumulative COVID-19 incidence rate before the vaccine was launched and the decline in the COVID-19 incidence rate between December 1, 2020 and March 1, 2021 – with the western region of the United States States to be particularly noticeable.

However, the cumulative vaccination rate and incidence rates must be viewed as statistically independent variables, highlighting the need to continue the ongoing large-scale adoption of vaccination.

“In light of confounding factors such as different coronavirus restrictions and mask mandates, different population densities, and different diagnostic tests and vaccine availability across US states, we are promoting a public health resource to improve transparency in monitoring vaccine effectiveness,” the emphasize Authors of the study medRxiv paper.

Delivery of an evidence-based message

In short, this study highlights the importance of linking the current vaccine rollout with real-time monitoring of the spatiotemporal efficacy of the vaccine in order to turn the tide of the COVID-19 pandemic. This must be viewed as a data-informed endeavor as it affects strategies in other parts of the world as well.

“Even when people are waiting to be vaccinated, there have been reports of subpopulations who refuse to be vaccinated because of misinformation about the safety and effectiveness of vaccines being boosted through social media,” the study authors say.

Given the real world evidence that has been gathered about the effectiveness and safety of the vaccine for those who have been vaccinated, this study (and associated resources) highlights the positive public health impact of the vaccination campaign, in addition to motivating the global adoption of vaccines to the vaccination to finally stop the COVID-19 pandemic in its tracks.

* Important NOTE

medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.

New county-level data showing the relationship between aggressive vaccination and parentage in cases: //t.co/pYEfIVkcHV (preprint) pic.twitter.com/3UpCej7nPc

– Eric Topol (@EricTopol) March 8, 2021

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