The old US hot spots Covid-19 are the new hot spots

Public health officials and epidemiologists say the increased number of cases in many parts of the country can be attributed to a constellation of factors, including the spread of more transmissible variants; an increase in infections in younger people, often unvaccinated; relaxed prevention efforts and weak table restrictions and indoor masking; as well as pandemic fatigue.

A family model

After a sharp drop in mortality, recent cases reported by Covid-19 remained high in the United States, but some states saw cases jump back higher. It seems to follow a familiar pattern. When cases reached their peak in mid-April 2020, New Jersey, Michigan, Pennsylvania and New York were leading this growth.

However, when the nation reached a new high at the end of July, those four states were at low points as the pandemic center moved south and west. They grew again in the winter, along with the rest of the US, and are now the driving force behind this year’s latest growth.

Epidemiologists and public health authorities in Michigan have shown that school sports are a major source of Covid-19 transmission. In addition, at the national level, major outbreaks have been linked to the recent Easter holiday and spring break.

The ascent in variants

The UK variant is now the dominant variant in the USA. The Upper Midwest, including Michigan and Minnesota, where cases have been raised, has some of the largest known cases of the UK variant. Stem cases are also high in Tennessee and Florida. The variant was reported in each state.

Regional versions of the virus, first detected in New York and California, are also gaining ground. Like the UK version, they may be more transmissible than previous versions of the virus, the researchers suspect.

The prevalence of several infectious variants initially detected in South Africa and Brazil remains low in the US, but given the lack of large-scale genetic sequencing, the Centers for Disease Control and Prevention cannot provide accurate incidence rates for all of this.

The Biden administration announced on Friday a $ 1 billion investment in expanding genomic sequencing in the CDC, states and jurisdictions as part of the $ 1.9 trillion Covid-19 aid package signed into law last month. The money will support the collection of Covid-19 specimens, sequencing and data exchange to help identify virus mutations.

Younger people infected

Older patients have traditionally experienced more severe cases of Covid-19, with higher death rates and hospitalizations. Higher vaccination rates among older people, who have been given priority for vaccinations, have begun to reshape this trend – which could help increase the proportion of severe cases among younger patients.

Recently, infections and hospitalizations among people under the age of 55 have increased.

“Hospitals are seeing more and more younger adults – those between the ages of 30 and 40 – admitted with severe illnesses,” said Dr. Rochelle Walensky, director of the CDC, recently. “So what we really want to do is expand vaccination more and more, so that we can be in a place where we have … more vaccinations there and really fewer diseases that circulates ”.

About 25.4% of people in the US have been completely vaccinated, according to the Centers for Disease Control and Prevention. About 50.4% of Americans aged 18 and over and 39.5% of the total population received at least one dose of vaccine, CDC data show.

The new reported cases fell from a day earlier, to 42,018 reported for Sunday after 52,373 were reported for Saturday, according to the latest data compiled by Johns Hopkins University. The number of new cases recorded each day tends to be lower at the beginning of the week, as fewer people are tested and many states do not report data on weekends.

—Alberto Cervantes contributed to this article.