coronavirus cases1

United States coronavirus cases have increased again after hitting a low point late last month, and some of the states driving the upward trend have also been hit hardest by variants, according to an analysis of data from Helix, a lab testing company.

cases trended steeply downward in the first quarter of the year, falling by almost 80 percent from mid-January through the end of March.

But during that period, states also rolled back virus control measures, and now mobility data shows a rise in people socializing and traveling.

Amid all this, more-contagious variants have been gaining a foothold, and new cases are almost 20 percent higher than they were at the lowest point in March.

Michigan has seen the sharpest rise in cases in the last few weeks.

B.1.1.7 — the more transmissible and more deadly variant of the coronavirus that was first discovered in the United Kingdom — may now make up around 70 percent of all of the state’s new cases, according to the Helix data.

The vaccines authorized in the United States are very effective against the B.1.1.7 variant and will significantly slow virus spread once a large share of the population is vaccinated.

Some experts estimate 70 to 90 percent of the population would need to acquire resistance before transmission would substantially slow.

As of April 5, less than 20 percent of the U.S.

Connecticut, New Jersey and Pennsylvania, among others, are all experiencing marked rises in case counts, and labs have identified both the B.1.1.7 variant and large shares of another variant, B.1.526.

The B.1.526 variant, which first appeared in New York City in samples from November, appears in two forms: one with a mutation that may help the virus evade antibodies and another that may help it bind more tightly to human cells.

The rapid spread of the B.1.526 variant, which made up more than 40 percent of sequenced cases in New York City as of mid-March, has prompted officials to say they believe it also could be a more infectious strain, though they say it is too early to tell whether it results in a more severe illness.

There is not enough genomic sequencing, the resource-intensive process required to discover that a case has been caused by a variant, to be certain how exactly much B.1.526 is spreading in the Northeast, but the available data indicates it is likely widespread.

the virus.

the virus1

The outbreak in the Northeast is currently much worse than it is in California, but California faces a variant of its own that makes up a large share of cases.

Studies have indicated the variant first discovered in California, B.1.427/B.1.429, may also be more transmissible than earlier forms of the virus, but it does not appear to spread as quickly as B.1.1.7.

It was discovered in more than half of samples tested in Los Angeles in mid-January, suggesting that it may have helped fuel the state’s enormous winter surge, which hit Southern California hardest1

the virus1

the virus

Like the variant first discovered in New York City, the B.1.427/B.1.429 variant has also been seen in high levels in neighboring states, including Arizona, but does not yet make up a significant number of cases outside the region

Higher vaccination rates among the country’s older adults — those prioritized first in the vaccination rollout — mean that some of those at highest risk of complications are protected as cases rise again

But almost 70 percent of the U.S

And in many states, those with high-risk conditions or in their 50s and 60s had not yet or had only just become eligible for the vaccine when cases began to rise again, leaving them vulnerable

Other states with rising cases are also seeing significant increases in hospitalized Covid-19 patients

Nationwide, the uptick in the number of hospitalized Covid-19 patients is more subtle, but with a large divergence by age group: There is a clear recent increase in coronavirus hospital admissions among adults under 50

Hospitalized Covid-19 patients

Covid-19 patients by age group

Hospitalized Covid-19 patients by day

Covid-19 patients by age group

The vaccine rollout continues to speed up, and recent studies confirm that vaccines are effective against the coronavirus in the real world, giving experts hope that an end may be in sight