What is the BA.5 variant and why does it seem to be reinfecting so many people with COVID-19?


BA.5, part of the Omicron family, is the latest variant of coronavirus causing widespread waves of infection around the world.

According to the most recent report from the World Health Organization, it was behind 52% of cases sequenced at the end of June, compared to 37% in a week. In the United States, it is estimated to cause about 65% of infections.


BA.5 is not new. First identified in January, it has been tracked by the WHO since April. read full story

It is a sister variant of the Omicron strain that has been dominant worldwide since late 2021 and has already caused spikes in case rates, even with reduced testing, in countries such as South Africa, where it was first found, as well as the UK, parts of Europe and Australia.

Coronavirus cases around the world have been rising for four weeks in a row, WHO data showed.


Like its closely related brother, BA.4, BA.5 is particularly good at evading the immune protection provided by vaccination or previous infection.

For this reason, “BA.5 has a growth advantage over the other Omicron sub-lineages that are in circulation,” Maria Van Kerkhove, the WHO’s technical lead on COVID-19, told a news briefing on Tuesday.

For many people, this means they are being reinfected, often even shortly after having COVID-19. Van Kerkhove said the WHO is evaluating reports of reinfections.

“We have ample evidence that people who have been infected with Omicron are becoming infected with BA.5. There is no question about it,” said Gregory Poland, a virologist and vaccine researcher at the Mayo Clinic in Rochester, Minnesota.

If that seems particularly common now, it could simply be because so many people received Omicron, the researchers suggested.


While the rise in cases has led to more hospitalizations in some countries, deaths have not risen dramatically.

This is largely because vaccines continue to protect against serious illness and death, if not infection, and manufacturers and regulators are also looking for modified vaccines that directly target Omicron’s newer variants.

There is also no evidence that BA.5 is more dangerous than any of the other Omicron variants, the WHO’s Van Kerkhove stressed, although spikes in cases may put health services under pressure and put more people with HIV at risk. prolonged COVID.

The WHO and other experts have also said that the ongoing pandemic, prolonged by vaccine inequity and the desire of many countries to “go beyond” COVID-19, would only lead to more new and unpredictable variants.

Scientists are already drawing attention to BA.2.75, first identified in India, which has a large number of mutations and is spreading rapidly.

The WHO said on Tuesday that the pandemic remained a global health emergency and that countries should consider public health measures such as wearing masks and social distancing when cases rise, along with vaccinations. read full story

“What people fundamentally don’t understand is that when there is this high level of community transmission, this will mutate,” Poland said. “Who knows what will come next. We are playing with fire.”

(Reporting by Jennifer Rigby in London and Julie Steenhuysen in Chicago; editing by Philippa Fletcher)

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