Since the first Covid-19 vaccines were approved in December, the U.S. has administered nearly 250 million doses, getting shots in the arms of more than four in 10 Americans. About a third of the population is fully vaccinated.
Those numbers are far from what experts say is probably necessary to achieve herd immunity, the point at which enough people become immune such that the whole community is protected. And the average daily rate of vaccinations has fallen by almost a third from its peak in mid-April.
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While those numbers are frustrating efforts to broaden the vaccinated population, the country does appear to have reached a tipping point in passing the 40% mark—a figure that many public-health experts call an important threshold where vaccinations gain an upper hand over the coronavirus.
NEW CASES PER 100,000, SEVEN-DAY AVERAGE
PEOPLE VACCINATED WITH AT LEAST ONE DOSE More new cases More vaccinations U.S. U.S. Top 10 Top 10 Bottom 10 Bottom 10
This chart shows how the seven-day average of new Covid-19 cases per 100,000 people has changed as more residents have received at least one vaccine dose. Since early March, after falling from a holiday surge that peaked in early January, daily case rates were mostly steady.
But as the country approached a vaccination rate of 40%, case counts began declining sharply.
States that gave more vaccines drove the decline. In the aggregate, the 10 states with the highest vaccination rates—all above 50%—recorded a steep drop in cases.
That contrasts with states where vaccination rates are lowest. This group, in aggregate, has lower case rates overall but has seen infections drop only modestly as vaccination rates lag.
Among those with the highest vaccination rates are states in the Northeast. After a surge in early spring, cases are sharply decreasing.
Other spring hot spots had fewer new cases after vaccinating about 40% of residents.
In contrast, new cases in the three states with the lowest vaccination rates have remained steady after initially falling below the U.S. average in early spring.
Some places to watch: warm-weather states where summer temperatures could force more gatherings in air-conditioned indoor settings.
Explore the data for yourself.
Note: Some dates are excluded due to irregularities in reporting.
Sources: John Hopkins University via Associated Press (cases); Centers for Disease Control and Prevention (state vaccinations)