EG.5.1 Covid variant takes off, India not at risk currently

EG.5, a descendent of the Omicron lineage of XBB.1.9.2, was designated a variant of interest (VOI) after risk evaluation by the World Health Organization on August 10, 2023. It was previously designated a variant under monitoring on July 19.

The WHO said EG.5 may spread globally and contribute to a surge in case incidence. However, at present, there is no evidence of an increase in disease severity directly associated with EG.5.

EG.5 was first reported on February 17 of this year. As of August 9, EG.5 has been reported from a total of 48 countries.

So far, in India, one EG.5.1 was detected in Maharashtra in May. On August 11, Union Minister of Health Mansukh Mandaviya assured that India need not worry about a surge in cases.

On the same day, according to the Ministry of Health and Family Welfare, India has 1,505 active cases. Of these, Kerala reported 1,004 cases.

Cases reported in other states include West Bengal (220), Uttar Pradesh (60), Maharashtra (98), Tripura (17), Sikkim (14), Odisha (13), Haryana (23), Delhi (7), Himachal Pradesh (10), Karnataka (17), Telangana (4), Mizoram (4), Gujarat (3) and Tamil Nadu (5). The remaining states reported 2 to 0 cases.

“Though not as extensively done as in 2021, global genome sequencing databases indicate the remarkable rise of the new sublineage. EG.5.1 is taking off everywhere. It is definitely out-competing its predecessors in the XBB lineage that were dominating most of 2023,” Rajeev Jayadevan, co-chairman of the National Indian Medical Association COVID Task Force confirmed to Down to Earth.

Comparing epidemiological week 25 (June 19-25, 2023) to week 29 (July 17 to 23, 2023), the global proportion of EG.5 relative to other circulating variants showed a notable increase, rising from 7.6 per cent to 17.5 per cent, the WHO report observed on August 9.

Similarly, among countries with over 1,000 EG.5 sequences, the prevalence of EG.5 rose from 24.7 per cent to 45.0 per cent for China, 5.6 per cent to 12.8 per cent for the United States of America, and 7.6 per cent to 19.3 per cent for the Republic of Korea, the WHO noted in the same report.

“Within six weeks of its discovery in South Africa in late 2021, Omicron arrived at almost every doorstep in India, such is the speed of new variants. Besides, increasingly we are seeing that previous infection by a closely related sublineage might not be able to stop newer Omicron descendants from circulating,” Jayadevan told DTE.

“While it has a low-individual risk for mortality, if it happens to sweep through vulnerable segments of a large population, the total number of deaths will be considerable,” Jayadevan told DTE.

“India’s testing rates have come down as cases have decreased. Surveillance however continues in India which will be able to tell us how this will pan out,” Jayadevan told DTE.

“Although initial symptoms tend to be mild, people should not take COVID lightly as we do not want infection to happen on a large scale. Besides the immediate impact on the health of vulnerable individuals, about one out of 20 people go on to get Long Covid lasting several months. These patients suffer in silence, with poor quality of life,” the expert warned.

The recent VOI classification of EG.5 suggests that due to changes in the receptor binding domain of the spike protein, the variant escapes neutralisation by antibodies generated from previous infections or vaccinations, the Centers for Disease Control and Prevention says.

EG.5 carries an additional F456L amino acid mutation in the spike protein compared to the parent XBB.1.9.2 subvariant and XBB.1.5. Within the EG.5 lineage, the subvariant EG.5.1 has an additional spike mutation Q52H and represents 88 per cent of the available sequences for EG.5 and its descendent lineages, the WHO explained.

While waning immunity and frequent mutations are commonly cited reasons for the continued circulation of the SARS-CoV-2 virus, authors of a recent pre-print study in Japan were unable to pinpoint the reason why EG.5.1 is selectively rising.

Research by The Sato Lab (Kei Sato), division of systems virology at the Institute of Medical Science, University of Tokyo found that the rise of EG.5.1 is attributed to neither increased infectivity nor enhanced immune evasion. They found it was immune evasive as expected, but not any more than its peers in the Omicron lineage.

Thus, they believe that the emergence and spread of EG.5 is driven by other pressures that are yet to be ascertained.

As of August 6, 2023, over 769 million confirmed cases and over 6.9 million deaths have been reported globally since the pandemic broke out in March 2020, the WHO’s weekly epidemiological update on COVID-19 published on August 10 said. 

Globally, nearly 1.5 million new COVID-19 cases and over 2500 deaths were reported in the last 28 days (July 10 to August 6, 2023), an increase of 80 per cent and a decrease of 57 per cent, respectively, compared to the previous 28 days.

“While concurrent increases in the proportion of EG.5 and COVID-19 hospitalisations (lower than previous waves) have been observed in countries such as Japan and the Republic of Korea, no associations have been made between these hospitalisations and EG.5. However, due to its growth advantage and immune escape characteristics, EG.5 may cause a rise in case incidence and become dominant in some countries or even globally,” the update said.

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