Will achieving herd immunity be a road to success to end the COVID-19 pandemic?

Abstract

As the COVID-19 pandemic continues, the availability of several different new vaccines, their varying supply levels, effectiveness, and immunity duration across different ethnic populations, together with natural infection rates, will have an impact on when each country can reach herd immunity (ranging from 15.3% to 77.1%). Here we estimate the population proportions still required to gain immunity (ranging from 0.01% to 48.8%) to reach an overall herd immunity level to stop the exponential virus spread in 32 selected countries.

Keywords: Basic reproductive number; COVID-19; Herd immunity; Vaccination.

Fig. 1

Proportion of population already immune ($P_{im}$) (red) and the additional proportion still required to achieve herd immunity ($P$) (blue) in the 32 study populations stratified by vaccine availability for various key priority groups. With the most recent data for the numbers of vaccine doses given and naturally occurring COVID-19 cases, as reported from each country's population on 26^th May 2021,¹ assumed estimates for $V{E}_1$, $V{E}_2$, and $P_{ni}$ to be 70%², 88%³ and 80%^4,5, respectively, $P_{im}$ can be estimated. Percentages to the right of each bar represent the minimum proportion of the total population required to recover from COVID-19 to confer immunity with vaccine availability $\left(P_{crit}\right)$. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.). References 1 Coronavirus (COVID-19) Vaccinations. Available at https://ourworldindata.org/covid-vaccinations. Accessed April 28, 2021, n.d. 2 Lopez Bernal Jamie, Andrews Nick, Gower Charlotte, Robertson Chris, Stowe Julia, Tessier Elise, et al. Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study. BMJ 2021;373:n1088. 3 Bernal Jamie Lopez, Andrews Nick, Gower Charlotte, Gallagher Eileen, Simmons Ruth, Thelwall Simon, et al. Effectiveness of COVID-19 vaccines against the B.1.617.2 variant n.d. Doi: 10.1101/2021.05.22.21257658. 4 Boyton Rosemary J, Altmann Daniel M. Risk of SARS-CoV-2 reinfection after natural infection. Lancet 2021:1161–3. 5 World Health Organization. COVID-19 natural immunity: scientific brief, 10 May 2021. World Health Organization; 2021.