Studies suggest a SARS-CoV-2 vaccine distribution strategy focused on where the virus spreads more easily

It’s been a few days since the United States achieved its goal of immunizing 100 million people 100 days after President Biden took office. Although the United States leads the world with more than 29.7 million cases of COVID-19 and more than 539,000 deaths, it has established itself as a leader in population vaccination.

However, with current vaccination strategies, Basic reproduction number (R₀), This helps to estimate the spread of COVID-19 cases.

New preprint research treatise published in medRxiv* A server by Anthony R. Ives of the University of Wisconsin-Madison and Claudio Bozzuto of Wildlife Analysis GmbH suggests that current vaccination efforts will reach the United States. Herd immunity In about 4.5 months. However, they advocate more cost-effective and more effective vaccine strategies that take geography into account. This helps to assign vaccines to populous counties that tend to be low-ranking and ethnic minority populations. These counties will currently be the last counties to reach herd immunity under current vaccine distribution strategies.

The author writes:

“From an epidemiological point of view, the difference in R is₀ Intercountry values ​​are partially dependent on population density, with counties at highest risk of resurrection and severe outbreaks finally reaching herd immunity. From a socio-economic point of view, these dense counties include many of the counties that are the economic engine of the United States. Finally, the densely populated counties have a relatively large population of African Americans, and current distribution plans lag about four days behind whites in reaching herd immunity. “

The proposed vaccination strategy targets counties with high R₀ Numbers

Given the high risk of spreading the virus in the urban environment, a high population density gives a high estimate of R.₀.. Therefore, the authors argue that vaccination strategies should target dense populations in order to reach herd immunity faster and avoid more COVID-19 cases.

To calculate this, they tracked the proportion of the US population that would reach herd immunity under current distribution strategies. Since March 15, 2021, they envision the following: The current vaccination rate using any of the three FDA-approved vaccines (Moderna, Pfizer-BioNTech, or Johnson & Johnson) is 1.58 million per day if 71.1 million people have already been vaccinated. Will be. With at least one vaccination, the vaccine is 90% effective and vaccinated people cannot spread COVID-19.

Their results show that US herd immunity can be reached in about 130 days.

Viable and efficient allocation of SARS-Cov-2 vaccine according to R0. Panel (a) shows the percentage of the US population living in counties that have reached herd immunity, calculated as 1 – 1 / R0 at the county level. The 0th day of the x-axis is March 15, 2021. The black line assumes the current distribution of vaccines evenly distributed to the county according to population size. The red line assumes that the distribution depends on the estimated R0 value at the county level. Panel (b) shows the average population density (population per km2) of counties reaching herd immunity in a weekly time frame. Panel (c) shows the percentage of white and African-American communities living in counties that have achieved herd immunity.

New plans reach herd immunity faster in all counties

In contrast, their analysis suggests that the proposed strategy helps the United States reach nearly the same herd immunity in all counties 51 days earlier than current vaccination strategies. In addition, the United States will eventually use 39% less vaccine under the new plan.

“These results depend on R₀A base strategy starting in mid-March. Overall profits are expected to diminish as population-based strategies are maintained. “

Variants of new concerns from the United Kingdom, South Africa and Brazil have pointed out that these estimates may change and may require more vaccination.

To account for the higher transmission rates of the new variants, they adjusted the formula to include 1.5 times higher transmission than was originally measured at the start of the 2020 pandemic.

The findings show that the strategy proposed by the researchers has reduced the time to reach herd immunity by 76 days and consumes less than 35% of the vaccine dose in the United States.

Evidence confirms that increasing vaccination efforts in populated counties is fairer and more efficient, uses fewer vaccines in the long run, and reaches herd immunity faster.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.