Omicron: The map and the terrain

Omicron can stand a real chance if fatigue in community mitigation strategies and test-track-treat strategy are not quickly shaken off

The World Health Organization (WHO) designated variant B.1.1.529 a variant of concern, named Omicron, on November 26, 2021. This has put the world on tenterhooks, with countries scrambling for potentially turbulent times ahead after a relative calm of several months.

A navy engineer in Thane, Maharashtra, who tested positive for Covid-19 after returning from South Africa, has been kept in isolation, and his sample has been sent for genome sequencing. Two South African citizens in Bengaluru tested positive, and the state health minister reportedly said the sample of one of them is "different from the Delta variant". Another person in Chandigarh who returned from South Africa has tested positive alongside his family contacts; their samples await genome sequencing.

While some of them can turn out to be the first detected Omicron cases in India, it is likely to have slipped through undetected even earlier, as in several other countries across the world. The Union health minister confirmed in Parliament that "no case of Covid-19 variant Omicron has been reported in India so far."

What happened in Gauteng province, South Africa?

An index case, in epidemiology jargon, is the patient in an outbreak who is first noticed by the health authorities and who makes them aware that an outbreak might be emerging. As in the HIV pandemic, the primary case will never be known, but there will always be one (or even more). South Africa's National Institute for Communicable Diseases (NICD) reported 77 samples collected from Gauteng province between November 12-20; the first confirmed infection was from a specimen collected on November 9 2021. With 1.5 per cent of the country's land area, more than a quarter of the country's population lives here. The province is home to several large urban agglomerations, including Johannesburg, a megacity with international air traffic of about 10 million passengers. The province has the highest density for both HIV prevalence and persons living with HIV (PLHIV); add to this that 80 per cent of all areas in the country were identified as underserved areas. Persistent SARS-CoV-2 infection with accelerated intra-host evolution has been reported in patients with advanced HIV and antiretroviral treatment failure from South Africa. This is an important working hypothesis in the emergence of this variant.

It currently affects those under the 25 years age group in South Africa, about a quarter of whom are vaccinated. Reports from South Africa have sought to establish correlations between the local elections and the rapid spread of the new variant not just in the Gauteng province but in other provinces too.

Why is the WHO worried, and how has the globe responded?

The WHO is concerned as the genetic profile of B.1.1.529 carries over 30 mutations in the spike protein, which makes up most of the vaccines. Some of the genetic changes are known to have worrisome features affecting transmissibility and immune evasion. In response to

the genomic evidence, it was declared as a 'variant of concern'. The story of C.1.2 is not dissimilar. Also originating in the Gauteng and Mpumalanga provinces of South Africa in May 2021, it had also "mutated substantially" from the original Wuhan variant. It raised similar worries, too, spread across Europe and Asia but failed to dislodge Delta as the dominant variant.

The emerging evidence for Omicron shall be keenly watched to detect the increase in transmissibility or "detrimental change in Covid-19 epidemiology"; increase in virulence or change in clinical disease presentation; or decrease in public health and social effectiveness measures or available diagnostics, vaccines, therapeutics. As far as we know at present, there is evidence of rapid spread in South Africa, but clinical symptoms are mild, i.e., there is no increased virulence, and it remains largely detectable by current tests. The jury is out on whether existing vaccines are sufficient against Omicron or whether an updated vaccine is required. The WHO has clarified that it will be several weeks before definitive evidence emerges on these epidemiological features.

Notwithstanding the available evidence and caveats, several countries banned flights from South Africa (and several other countries in the region) while Germany labelled it as a "virus variant area". President Cyril Ramaphosa termed these restrictions "not informed by science".

The detection and rapid spread of this variant in southern Africa have rekindled debates on vaccine inequity. The global share of the population vaccinated with fully against Covid-19 is 43 per cent, and the corresponding figure for South Africa is about 24 per cent and nearly seven per cent for the continent as a whole. It has also brought to focus the inability of WHO's Covax initiative (intended to supply almost a hundred low-income countries) to acquire both doses and funds amidst ongoing hoarding by wealthy economies for boosters.

What will it mean for India?

Serosurveys at both national and state levels point to about 90 per cent seropositivity on account of both natural infection and vaccination. There is little difference in seropositivity among urban and rural populations or adults and children in most states. An absence of any post-festival surge (in October and November) confirms continuing high levels of protection. The AY.4.2 variant, also known as "Delta Plus", is about 10–15 per cent more transmissible than the Delta variant. While first detected in the country in April 2021, it has not been able to establish itself in any significant manner so far. Unless the Omicron has the substantial ability for breakthrough infections, Indian populations may continue to be relatively protected.

About a third of the total population is now immunised with two doses and about 58 per cent with a single dose. 'Patchwork vaccination' signifies pockets of low coverage of vaccination among areas with high levels of coverage; such areas are vulnerable to 'hyperlocal outbreaks' and may emerge as hotspots should the new variant get introduced. India's current concern is vaccine complacency in the backdrop of low numbers of daily new cases leading to large numbers not completing the full schedule. Nearly 2.7 million health and frontline workers are yet to complete their full schedule despite vaccination beginning for them early this year. Prior infection-induced immunity protects against reinfection, but this acquired immunity wanes over time, and vaccine complacency can prove to be costly in the wake of this new variant. Also being closely awaited is the policy on additional and booster doses by the National Technical Advisory Group on Immunisation (NTAGI) in the next few weeks.

While central and state governments are gearing up to rise to the challenge, Omicron can stand a real chance if fatigue in both community mitigation strategies - face masking, physical distancing, respiratory etiquette, and washing and indoor gatherings - as well as test-track-treat strategy, are not quickly shaken off.

(The writer is Chairperson at the Centre of Social Medicine & Community Health, Jawaharlal Nehru University, New Delhi)

Disclaimer: The views expressed above are the author's own. They do not necessarily reflect the views of DH.

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