What does the BA.5 subvariant mean for America?

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

Known as a subtype of Omicron BA.5 now dominatesAlong with another subtype, BA.4, it drives cases and hospitalizations, according to federal estimates released Tuesday.

America

Est. Share of cases from Omicron categories

January 1

4th of July

50%

100%

BA.1

BA.2

BA.4

PA.2.12.1

BA.5

New cases per 100,000 people

January 1

4th of July

100

200

BA.5

proof’s: CoVariants.org; GISAID; New York Times Database of Cases and Deaths | Note: Charts show 14-day case averages, and frequency of variations in cases is an estimate. Sequential rates reflect localized trends based on testing in a particular region or hospital. Charts show latest available data, may be lagging and may change as additional series are completed. Recent data are based on small samples and are particularly variable.

Although the popularity of home testing means that the actual infection rate is significantly underreported, the share of tests that come back positive is shooting upwards and is now higher than in other waves of the epidemic. According to the CDC, the risk of Covid-19 is increasing across much of the country.

“I think there’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 about the subgenre.

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

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Waves of infection – and the immunity that accompanies them – vary across countries and make for imperfect comparisons. Vaccination rates also vary. But where BA.4 and BA.5 predominate for weeks or months, secondary variants have caused an increase in cases and hospitalizations, despite some population immunity from previous waves.

Covid-19 hospitalizations per 100,000 people

South Africa

January 1

4th of July

25

50

BA.4 + BA.5

dominant

Sources: Our World in Data, CoVariants.org, Centers for Disease Control and Prevention, US Department of Health and Human Services. | Note: BA.4 and BA.5 are the dominant term assessments.

The CDC says there is no evidence yet that BA.4 or BA.5 is inherently more severe 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 the omicron variant confers some degree of immunity, Dr. Tobol said, and may explain why cases in the United States have not yet begun to take off in earnest. “But nothing like what we expected,” he said. Omicron subvariants represent escape from previous waves of virus, making previous infection more likely to protect against reinfection.

In Portugal, where vaccination rates are higher than in the US, cases rose sharply after BA.5 dominated in May, and hospitalizations neared the previous Omicron peak.

Portugal

Est. Share of cases from Omicron categories

January 1

4th of July

50%

100%

BA.1

BA.2

BA.5

No
Sorting
Information

New cases per 100,000 people

January 1

4th of July

200

400

No
Sorting
Information

proof’s: CoVariants.org; GISAID; New York Times Database of Cases and Deaths | Note: Charts show 14-day case averages, and variant frequencies are estimates from CoVariants pooled at two-week intervals. Sorting based on testing in a particular region or hospital may reflect localized trends. Charts show latest available data, may be lagging and may change as additional series are completed. Recent data are based on small samples and are particularly variable.

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Before BA.4 and BA.5 dominated South Africa in April, research suggested 98 percent of the population Some antibodies were present from vaccination 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 cause small increases in cases, hospitalizations and deaths.

South Africa

Est. Share of cases from Omicron categories

January 1

4th of July

50%

100%

BA.1

BA.2

BA.4

BA.5

No
Sorting
Information

New cases per 100,000 people

January 1

4th of July

25

50

No
Sorting
Information

proof’s: CoVariants.org; GISAID; New York Times Database of Cases and Deaths | Note: Charts show 14-day case averages, and variant frequencies are estimates from CoVariants pooled at two-week intervals. Sequential rates reflect localized trends based on testing in a particular region or hospital. Charts show latest available data, may be lagging and may change as additional series are completed. Recent data are based on small samples and are particularly variable.

Places emerging from significant spring waves of the virus may also not be spared. A different Omicron sub-variant, BA.2, has erupted in large numbers in several countries in Europe, leading to new hospitalizations and deaths that recently peaked in April. Yet in those countries, cases are rising again as BA.5 predominates.

France

Est. Share of cases from Omicron categories

January 1

4th of July

50%

100%

BA.1

BA.2

BA.5

No
Sorting
Information

New cases per 100,000 people

January 1

4th of July

200

400

No
Sorting
Information

Italy

Est. Share of cases from Omicron categories

January 1

4th of July

50%

100%

BA.1

BA.2

BA.5

No
Sorting
Information

New cases per 100,000 people

January 1

4th of July

100

200

No
Sorting
Information

proof’s: CoVariants.org; GISAID; New York Times Database of Cases and Deaths | Note: Charts show 14-day case averages, and variant frequencies are estimates from CoVariants pooled at two-week intervals. Sequencing rates vary between countries and sometimes reflect localized trends based on testing in a particular area or hospital. Charts show latest available data, may be lagging and may change as additional series are completed. Recent data are based on small samples and are particularly variable.

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

The U.S. has a lower vaccination rate than many of those countries, and a much lower share of seniors who have received one or two booster shots.

“A wave is hitting, there’s no question about it,” Dr. Topol said. “My concern is its length.”


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