Source page: McKinsey & Company
Commentary
Coronavirus vaccines are coming, but how effective will they be, and how widely adopted?
COVID-19 | Public Health
November 2, 2020 – The answers affect progress toward herd immunity—and the end of the pandemic. Click through the four plausible scenarios below to see how much natural immunity would be needed (achieved through exposure and other means) to supplement vaccines of different effectiveness and adoption levels.
Interactive
To read the article, see “When will the COVID-19 pandemic end?,” September 21, 2020.
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Visual form
Scenario scatter chart on a vaccine efficacy-versus-coverage grid.
Layout / body structure
The chart is organized as a two-axis scenario map with vaccine coverage on the horizontal axis and vaccine efficacy on the vertical axis. Read the numbered scenarios against the grid first, then use the surrounding annotations to see whether herd immunity can be achieved through vaccination alone or would still require natural immunity.
What is being compared
The chart compares four plausible combinations of vaccine efficacy and vaccine adoption or coverage. It shows how those combinations change the amount of natural immunity that would still be needed to reach herd immunity.
Measurement system
The horizontal scale is vaccine coverage in percent and the vertical scale is vaccine efficacy in percent. The annotations also track the natural-immunity level required for herd immunity in percent, with the chart anchored to an assumed herd-immunity threshold of 58 percent.
Visible structure inside the graphic
The visual is built as a rectangular coverage-by-efficacy grid with four numbered scenario points placed inside it. Text callouts beside the points label the scenarios as optimistic, midpoint, high coverage, and pessimistic, while an annotated threshold region marks where herd immunity is achieved through vaccine alone and where additional natural immunity would be needed.
Main takeaway from the visual
The chart shows that vaccine efficacy and vaccine coverage both matter, and that vaccination by itself may still fall short of herd immunity in several plausible cases. The more pessimistic combinations sit farther from the vaccine-alone threshold and therefore imply a larger need for natural immunity from prior exposure.
Key standout values or extremes
The chart is anchored to a 58 percent herd-immunity threshold based on an assumed basic reproductive number of 2.4. The natural-immunity scale is shown in 10-point steps up to 30 percent, and the four scenarios span from an optimistic case tied to roughly 70 percent early willingness to receive a vaccine to a pessimistic case with lower flu-like adoption ceilings.
Controls / sequence, when applicable
The embedded chart is presented as four clickable plausible scenarios, so the reader moves scenario by scenario to compare how different efficacy-and-coverage combinations change the natural-immunity requirement.
Companion media, when applicable
There is no separate companion audio or video; the chart is the full visual on this page.