BA.5 What does subvariance mean for the US?

A highly contagious variant of the coronavirus threatens new infections in the United States, including among people who have recently recovered from the virus.

Known as a subtype of Omicron BA.5 now dominatesWith another subcategory, BA.4, it accounts for more cases and hospitalizations, according to federal estimates released Tuesday.

While the popularity of home testing means that the true infection rate is significantly underreported, the rate of tests that come back positive is rising and is now higher than for other infections. According to the CDC, the risk of Covid-19 is increasing across much of the country.

“I think that’s an underestimation of what it’s going to do to the country, and it’s already having an effect,” said Eric Topol, professor of molecular medicine at Scripps Research. Written in sub†

BA.5 and BA.4, the subtypes of the Omicron variant that took the world by storm this winter, are versions of the virus that are more adept at evading immunity against previous infections and vaccines. Both types have mutations in their spike proteins that differ enough from earlier versions of the virus that some antibodies can block them.

Waves of infection — and accompanying immunity — vary from country to country and make for imperfect comparisons. Vaccination rates also vary. But where BA.4 and BA.5 predominate for weeks or months, secondary variants have led to an increase in cases and hospitalizations, despite some population immunity from previous waves.

The CDC says there is no evidence yet that BA.4 or BA.5 is inherently more serious than other omicron subtypes, but as more people become infected, the number of hospitalizations due to the virus may rise.

Previous infection with another form of omicron variant confers partial immunity, Dr. Tobol, and that may explain why cases in the United States have not yet begun to take off in earnest. “But it’s not what we expected,” he said. Omicron subvariants represent escape from previous viral waves, thus protecting against re-infection from previous infection.

In Portugal, where vaccination rates are higher than in the US, cases rose sharply after BA.5 dominated in May and hospital admissions neared pre-Omicron peaks.

Before BA.4 and BA.5 dominated South Africa in April, research suggested: 98 percent of the population There were some antibodies to the vaccine or previous infection or both.

Even with those protective antibodies, many people in the country are still infected with BA.4 and BA.5, and sub-variants account for small increases in cases, hospitalizations and deaths.

Areas exposed to significant spring waves of the virus should also not be left out. Another Omicron subtype, BA.2, has erupted in large numbers in several countries in Europe, leading to new hospitalizations and deaths that recently peaked in April. But cases are increasing again because of PA5 in those countries.

Experts say it’s too early to fully predict what the new subtypes might bring to the U.S., which had recent waves of the virus in May and June, driven by BA.2 and another subvariant called BA.2.12.1. The high rates of recent infections from BA.2.12.1 are unusual in the United States, where there are now waves of BA.4 and BA.5 infections.

Vaccination rates in the United States are lower than in many countries, and the percentage of seniors who have received one or two booster shots is much lower.

“There’s a wave coming, there’s no doubt about it,” said Dr. Topol. “My concern is length.”

Follow the Corona Virus