Why we must not take Omicron lightly

Omicron, the new variant of SARS-COV-2 virus, hit world headlines last month and since then, it has spread to 108 countries. India, too, has been seeing a surge of cases of Covid-19 in the last two weeks, with an alarming positivity rate of 3.64 per cent in Delhi on January 1. There is no denying that we are in the midst of the third wave of the Covid-19 infection.

India has already recorded around 2,000 cases of Omicron. These numbers may not, however, be the true reflection of the actual figures since they are based on genome sequencing, which is being done for only about 1 per cent of the cases. With impending elections in many states and poor compliance with Covid-appropriate behaviour guidelines, India could see a rapid increase in the numbers.

The second wave of Covid-19 in April-June had devastated the nation because we had started believing that we had some kind of natural immunity and that we had won over the virus. How wrong were we!

The new variant has around 50 mutations, with 32 of them in the spike protein, and some of them in the region that promotes virus’ entry into the host cells. These mutations imply that the variant is more infectious, spreads rapidly and also can escape immunity conferred by previous infection or vaccination. The doubling time for the new variant is much shorter than that of the Delta variant, which suggests that it spreads faster. In a few weeks, it can become the dominant strain in any community it infects.

While Omicron is more contagious and multiplies rapidly, it seems to be causing a less severe disease. Laboratory studies show it multiplies rapidly in the upper respiratory passages, but does not penetrate the lungs per se as much, thereby not causing severe lung injury which could result in hypoxemia.

Studies from the UK suggest people catching Omicron are 50 to 70 per cent less likely to need hospital care compared with the previous variants. Data from South Africa show that while hospitalisations increased by 70 per cent there, the ICU occupancy remained low at 7.5 per cent, with less than 14 per cent hospitalised patients requiring supplemental oxygen. The death rates have remained low, both in the UK and South Africa.

A recent, yet to be published report, from Manchester, UK, has, however, suggested that there is no decrease in hospitalisations due to Omicron as compared to Delta.

The symptoms of Omicron are somewhat different from Delta, with running nose, sore throat, cough and fatigue, especially in the fully vaccinated. Significantly, a majority of the cases may not have any symptoms at all. In the unvaccinated, there is fever, with chances of a severe disease. In the US, hospitalisations due to Omicron are primarily in the unvaccinated individuals. Children, too, are getting admitted.

The situation in India is likely to be no different. The illness can be more severe in the elderly or those with other diseases, like heart or chronic lung disease and those on chemotherapy or immunosuppressants. Even the common cold or influenza virus kills millions each year in people with compromised health.

What should be done if one tests positive? Asymptomatic and mild cases should be home-isolated so that other family members do not get infected. While the UK defines self-isolation as seven days, in the US, it is five days. For people who are elderly or have comorbidities, consultation should be sought with a physician. Further intervention will depend upon clinical and laboratory parameters.

Experts have predicted that India is likely to see an increasing number of cases in the coming weeks, with a likely peak by mid-February. This can get compounded by election rallies in some states going to the polls. While there may not be as many severe cases this time as in the second wave, there are chances of panic, and the likelihood of testing and emergency facilities being overwhelmed.

One school of thought is that since Omicron generally causes a mild disease, its rapid spread may, in fact, boost the immunity of a large section of population, thereby helping us in the long run. But the uncertainties of severity of infection in the elderly, those with comorbidities and those yet unvaccinated (amounting to nearly 40 per cent of our population) should be a cause for concern.

On the other hand, laboratory data suggests that prior infection or vaccination or a combination of the two fail to neutralise Omicron effectively. The Pfizer vaccine has been shown to lose efficacy to 60 per cent by five months against the Delta variant, and below 40 per cent against Omicron. A booster increases effectiveness against Delta uniformly but there is not much data against Omicron. After much debate, the Indian Government has also allowed ‘precautionary dose’ to some groups of vulnerable people.

While the available evidence so far suggests that Omicron causes a milder disease, we should be wary in the coming months. A spate of cases in schools and colleges across the country confirms the need for vaccination for all. It is important to ensure that people who have hesitated to take the second dose be coaxed to get it.

In October, the WHO had laid down guidelines for booster shots which were to be administered to a vaccinated population that has completed a primary vaccination series when, with time, the immunity and clinical protection has fallen below a rate deemed sufficient in that population.

Experts point out lack of relevant Indian data. We do not have our own data on the degree by which immunity wanes at different intervals following vaccination. We should also know how many infections occur after a single dose and at different intervals after the second dose of Covishield or Covaxin. We also do not yet know whether a mix-and-match strategy for the booster dose of the two available vaccines is better than a single vaccine.

Omicron is a reminder that the world continues to struggle against the pandemic. Unless vaccine inequality ends and there remain pockets of vulnerable populations, the virus will find hosts to multiply with the potential to mutate further. The next variant may be a super-variant, who knows?

The onset of Omicron should be a warning to us to not be complacent. While the government handles vaccination, it comes back to us, the individuals, to do our bit — wear a mask, avoid crowded places, get the two shots (and the booster, too) and avoid unnecessary travel — to prevent the virus from overwhelming us.