How to deal with the Omicron challenge

New rules of the game are emerging and need to be learned fast

An Omicron led Covid-19 surge is beginning to gather momentum in India. Resembling a "really bad cold", it takes just three days to develop symptoms, become contagious and test positive. One in three Omicron cases shall have no symptoms but can infect others. With a doubling time of two-three days, the World Health Organization (WHO) confirms that it spreads significantly faster than the Delta variant in countries with documented community transmission. The Union Ministry of Health and Family Welfare put out a normative framework on December 21, 2021, and reiterated the earlier guidance regarding strategies for containment and restrictions with the district as a unit.

Testing and surveillance

A key challenge that has emerged in countries with rapid spread (and consequent load on the laboratories) of the Omicron variant is the time taken for RT-PCR samples, processed, and the results returned. A doubling time of as little as 1.5 to two days may render these of limited utility for public health containment measures. Rapid antigen tests or lateral flow tests have thus assumed greater significance. As the pandemic progressed, regulatory bodies approved these as "a new approach to combat the pandemic".

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These have played a key role in keeping educational institutions and workplaces open (testing up to twice a week). Self-administered tests are also advised before mixing with people in crowded indoor places when visiting someone who is at higher risk of getting seriously ill from Covid-19 or if one has been in contact with someone with Covid-19. Free home testing kits and community testing sites are increasingly being promoted.

The 5 per cent and 10 per cent test positivity rates (TPR) are considered as markers for kicking off stricter measures and restrictions. Through the Omicron phase, the weekly average TPR in South Africa ranged at an average of about 35 per cent through December. Even with daily new cases declining from a peak of 37,875 on December 12, 2021, to 3,232 cases on January 3, 2022, the TPR remained at a relatively high of 18.6 per cent. Omicron needs to make us rethink what has come to be recognised as conventional wisdom.

Why have some countries opted for 'minimal disruption'?

Omicron led Covid-19 surges across countries have been marked by stricter social distancing norms on the one hand and looser restrictions on the other. At least three realities seem to shape those opting for looser restrictions: 'decoupling' of hospitalisation in the backdrop of good vaccination coverage and a milder clinical disease, economic necessity and political imperatives. With peak infectivity one to two days before the onset of symptoms and up to three days afterwards, it has also meant reducing the period of those in home isolation to a week (with two negative tests).

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Different states in India have instituted measures ranging from limiting indoor gatherings to night curfews and even restricting flights from certain cities. If tests cannot be significantly ramped up and conducted large-scale at the community level, the infection shall continue to spread under the radar and render many of these partially effective at best.

Another vital issue is the rapid Omicron transmission among healthcare workers, with several medical institutions in India now experiencing outbreaks among their staff. Such outbreaks are liable to happen among other essential public service sectors as well. The UK is preparing for "worst-case scenarios" of 10 per cent, 20 per cent and 25 per cent absence rates; these outbreaks highlight the relevance of robust contingency plans to handle crises of this nature.

What about hospitalisation?

There is an emerging consensus that daily counts of new cases are not that relevant in this phase, and the parameter to monitor is hospitalisations. Hospital admissions are only one aspect of the severity and function of admission practices. Researchers continue to track data across different countries to understand how clinical markers of severity – use of oxygen, mechanical ventilation and deaths – are associated with Omicron. The jury is still out on whether the observed reduction in risk of hospitalisation can be attributed to immunity from previous infections or vaccination and to what extent Omicron may be less virulent.

Delhi had 6,000 active cases on January 1, 2022, with 247 hospital beds occupied and five patients on ventilator support. Contrast this to 6,600 active cases on March 27, 2021, when 1,150 oxygen beds were occupied, and 145 were on ventilator support. And 8,063 new cases were detected on January 2, 2022, in Mumbai, with 89 per cent cases reported to be asymptomatic; 503 were hospitalised, of whom 56 were put on oxygenated beds. Put differently, about half of those symptomatic required hospitalisation. Delta still remains prevalent while Omicron is on the rise; hospitalisation patterns require greater characterisation.

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A recent analysis of approximately half a million Omicron cases from England confirmed a reduced overall risk of hospitalisation compared to Delta. An 81 per cent reduction in the risk of hospitalisation was observed after three doses of vaccines compared to unvaccinated Omicron cases. In a context of 70.1 per cent of the population receiving two doses and 31 per cent a booster dose too, 43.2 per cent of those hospitalised had received two doses and 23.2 per cent a booster as well.

While seropositivity in most states in India is upwards of 90 per cent, about 40 per cent of the total population has received two doses and 60 per cent one dose. These factors are likely to interact and shape hospitalisation patterns across the states.

The WHO is worried, and India continues to prepare

The WHO cautions that with the significant growth advantage of Omicron over Delta, rapid community transmission is imminent, increasing hospitalisation and stressing health systems. The use of well-fitting masks, physical distancing, ventilation of indoor spaces, crowd avoidance and hand hygiene continue to be the mantra for reducing transmission. Interrupting chains of transmission will require enhanced surveillance with rapid testing and stricter cluster investigations and contact tracing of cases suspected to be infected.

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Covid-19 vaccination of eligible populations needs to be accelerated, prioritising unimmunised or partially immunised individuals at risk for serious disease. Public health and social measures (PHSM) in response to individual cases or clusters of cases are most effective when implemented in conjunction with community leaders and civil society. Effective community engagement will be crucial to escalating PHSMs in a timely manner to avoid overwhelming health care services.

(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.