Do I need to worry about Covid-19 again?

New data from scientists and vaccine makers Moderna and Pfizer/BioNTech suggests a newer, highly mutated Covid-19 variant is not as alarming as some experts feared when it was first detected several weeks ago.

Nicknamed “Pirola” on social media, the BA.2.86 Omicron subvariant is being tracked by the World Health Organisation (WHO) and the US Centers for Disease Control and Prevention (CDC).

What is new about Covid-19?

Covid-19 infections and hospitalisations have been rising in the US, Europe and Asia, but are well below previous peaks. The weekly US hospitalisation growth rate slowed for three weeks in August, according to CDC data for the week ended August 26.

As of August 30, CDC said the BA.2.86 variant was detected in at least four US states in people or wastewater. Delaware on Tuesday said it had detected a BA.2.86 infection at a hospital. The WHO has reported finding BA.2.86 in at least six countries.

According to CDC data, the EG.5 subvariant, a descendant of the Omicron lineage nicknamed “Eris” on social media that originally emerged in November 2021, now accounts for about a fifth of US Covid-19 cases.

A variant nicknamed “Fornax,” officially FL.1.5.1, is the next largest at 14.5% of US infections and represents a growing share of East Coast cases. A wide range of other variants account for smaller shares of the total, with BA.2.86 less than 1%.

Dr David Dowdy, an infectious disease epidemiologist at Johns Hopkins Bloomberg School of Public Health, believes FL.1.5.1 will become the predominant variant in the coming months, but he does not expect an infection wave like the one driven by Omicron last winter.

Dowdy suggested the surge in cases may be due to immunity from vaccination and infection wearing off since the last surge.

What do scientists say about BA.2.86?

Scientists have been keeping an eye on BA.2.86 because it carries more than 35 mutations in key portions of the virus compared to XBB.1.5, the dominant variant through most of 2023.

The dramatic changes — on par with the genetic shift seen in the Omicron variant compared with its Delta predecessor — raised concerns the new variant could cause a major surge.

Experiments testing versions of the virus in two US independent laboratories suggest that is unlikely, said Dr Dan Barouch, director of the Centre for Virology and Vaccine Research at Beth Israel Deaconess Medical Centre in Boston, whose lab led one of the studies.

His team tested lab-made versions of the virus in people who were vaccinated or previously infected and found antibodies against the variant were comparable or slightly higher than those against circulating variants.

Experiments done in the lab of Dr David Ho at Columbia University, as well as by teams in Sweden and China, had similar findings.

Will vaccines protect against new variants?

Barouch's studies also suggested newly updated vaccines will raise antibody responses “to some extent” against all circulating variants, including BA.2.86.

Moderna on Wednesday said clinical data showed its retooled vaccine generated a nearly nine-fold increase in human antibodies that can neutralise BA.2.86.

Pfizer said on Wednesday its updated Covid-19 shot showed neutralising activity against BA.2.86 and EG.5 in studies conducted on mice.

The updated shots are being reviewed by the US Food and Drug Administration and are expected to be available this month.

Reuters