European Omicron trends offer key lessons for Kerala

Public health experts say Kerala could face a unique situation of having both Delta and Omicron in circulation in the community, overwhelming health systems

As Kerala braces for a potential spread of Omicron virus variant in the days ahead, multiple plans and strategies will have to be implemented to ensure that the health system is not overwhelmed and non-COVID care is not hit as it was during the peak of the previous Delta wave.

“It is a different set of challenges that we might be up against this time, if a community transmission of the Omicron variant were to take place. After two years of dealing with the pandemic we know that there is no need for a knee jerk reaction. But there are huge uncertainties over at what point should we act and whether we should anticipate that the situation involving Omicron may turn out to be as bad as Delta was,” a senior public health expert says.

While real world data from South Africa always maintained that the Omicron variant caused less serious disease than Delta, public health experts seemed to be waiting for data from the UK and Europe to confirm this.

Till now, the Scientific Advisory Group for Emergencies (SAGE), UK has maintained that there was nothing to suggest that Omicron was any less severe than Delta.

However, the latest study from Imperial College, London concludes that the chances of Omicron-infected people being hospitalised is 20-25% less than those hit by Delta and that the chances of having a hospital admission of more than a day was less than 40-45%.

The study also says that this reduced severity of the disease could be upstaged by the greater transmissibility of Omicron, which can infect a large number of people all at once, and especially reach the vulnerable (elderly, those with co-morbidities and the immunocompromised) much faster than other variants did.

Public health experts point out that Kerala would be facing a unique situation of having both Delta and Omicron in circulation in the community. Going forward, either of these two or in combination can become a problem if test positivity rate goes over 10% and things can spiral out of control.

“The key metric that we should be looking at, in a situation of an Omicron surge, would be how fast hospital beds, ICU beds and oxygen requirements are moving and not case numbers. Once community transmission of Omicron starts, it will then run through everyone (the doubling time is just two days). One major concern would be that if healthcare workers are affected in large numbers, all patient care activities will break down. The absenteeism of healthcare workers in hospitals can precipitate a crisis and this we might have to anticipate and plan ahead,” says R. Aravind, Head of Infectious Diseases, Government Medical College, Thiruvananthapuram.

Even while acknowledging that Omicron might bring a less severe disease, it can put a lot many people in hospitals in a very short time — this would naturally include a large number of patients in the vulnerable category — stressing the health system. One challenge would be to ensure that tertiary care institutions are not overcrowded with mild cases and are free to handle serious cases of both COVID and non-COVID diseases.

“There is a category of people — those above 60 years, multiple co-morbidities, the immunocompromised — for whom Omicron need not necessarily be mild. As they were vaccinated much early, vaccine-derived immunity would have waned for them,” points out Dr. Aravind.

“Another main challenge is the high immune escape potential of Omicron which can evade both monoclonal antibodies (mAbs) and antibodies generated by vaccines or previous infection. This means that none of the mAbs currently used as life-saving drugs to prevent serious infection (Delta) in the vulnerable will work for Omicron infections and this might be a handicap,” he adds.

Public health experts point out that Denmark’s Omicron experience is something that should be taken note of by Kerala. Denmark with 77% background vaccination rate and a high level of previous natural infection — a situation akin to Kerala — was one of the first nations in Europe to experience the Omicron surge.

The picture emerging from both the UK and Denmark looks almost the same. Hospitalisations have surged but are now slowing down and showing signs of stabilising. The projected worst case scenario has not played out anywhere yet .

Even when data from South Africa, UK and Denmark point towards less hospitalisations and decreased severity, scientists are cautious because they are not sure whether the variant is intrinsically less virulent or if the reduced severity is because cases have so far been concentrated in the younger population. The uncertainties are too many, including the background vaccination and past infection rate in the population.

“In Denmark, 1% of the Omicron-affected required hospitalisation and 0.1%, needed ICU care. At the peak of Delta, Kerala had around 43,000 new cases a day. If Omicron can lead to a peak of around one lakh cases a day, then we should expect around 1,000 hospital admissions, with 100 needing ICU care daily. MCHs should tend only to those requiring ICU care while the rest of the hospitalisations should be managed by the hospitals in the periphery, suggests Dr. Aravind.

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