There would have been a surge in instances if the variant is already current in India as Omicron spreads two to 3 occasions quicker than Delta
Over 100 Omicron variant instances have been detected up to now in 11 States in India. Except for one case of a medical physician in Bengaluru who has been confirmed to be contaminated with the Omicron variant, the remaining have been detected in worldwide passengers arriving in India and their contacts.
A November 30, 2021 round from the well being ministry clearly mentions that efficient December 1, all passengers arriving from specified “at-risk” international locations will likely be required to bear an RT-PCR take a look at on arrival. And random testing is to be achieved on 2% of the entire flight passengers arriving from different international locations. Incidentally, the at-risk international locations record has not been up to date for the reason that round was despatched on November 30; it contains solely Europe, the U.Okay. and 11 different international locations.
While all optimistic samples are to be despatched for genome sequencing, passengers arriving from at-risk international locations should bear residence quarantine for seven days, retest on the eighth day of arrival in India and if unfavorable, additional self-monitor their well being for the subsequent seven days.
The testing strategy adopted now appears to be like fairly just like the one put in place early final 12 months when testing was confined to worldwide passengers and their contacts if the index case exams optimistic. While over 80 international locations have confirmed Omicron variant, the testing in India is confined to worldwide passengers. Positive samples despatched for genome sequencing to verify for the Omicron variant are virtually primarily restricted to worldwide passengers. Is India missing to establish the Omicron variant in the neighborhood by not a minimum of randomly sequencing just a few optimistic samples? Absence of proof is unquestionably not proof of absence.
Limited testing
“This depends on the extent to which we believe the Omicron variant has already spread in the country. Levels of overall testing are currently fairly low, at the level of 1-3 million daily but the problem is that most of these tests are being done in a small number of States, mainly Kerala, Maharashtra and Karnataka. Because of this, it is hard to figure out to what extent silent spread has already begun in other parts of the country or whether cases are picking up,” says Dr. Gautam Menon, Professor of Physics and Biology at Ashoka University.
Based on the velocity at which the Omicron variant spreads, scientists have mentioned one contaminated individual can unfold it to 3 or extra individuals. Scientifically talking, the R0 of the Omicron variant is over 3. The Omicron variant has been discovered to unfold two-three occasions quicker than the extremely transmissible Delta variant. As a end result, in different international locations, Omicron instances are doubling each two to 4 days, which is much shorter timeframe in contrast with the Delta variant.
Since the variant spreads quicker than the Delta variant, there would have been a surge in instances in India whether it is already current in the neighborhood. “For now, we have nothing that suggests a large-scale rise in cases so far, which might have been a consequence of Omicron,” Dr. Menon says in an e mail to The Hindu.
Incorrect take a look at kits used
Not solely are the testing charges throughout India low, many of the RT-PCR take a look at kits used in lots of States shouldn’t have a S-gene goal within the primer. The S-gene dropout within the BA.1 sub-lineage is used as a proxy for figuring out the Omicron variant. In the absence of take a look at kits with a S-gene goal, solely genome sequencing can establish the variant.
“We need more random testing to detect community spread in those States which are not already testing well, and we need to sequence some fraction of the positive cases, both symptomatic and random, on a priority basis to look for Omicron. Right now, we don’t have any evidence of large-scale transmission of Omicron but that could simply be an artefact of lack of testing,” he says.
In the absence of elevated testing and genome sequencing, one other layer of complexity in noticing a surge in instances is perhaps associated to the gentle nature of the illness attributable to the variant in those that are already protected. While the Omicron variant could cause reinfections in individuals who have been beforehand contaminated and trigger breakthrough infections in totally vaccinated individuals and even amongst those that have acquired a booster shot, the instances principally have solely gentle illness.
Missing the gentle instances?
With a big proportion of the inhabitants in India being naturally contaminated, over 57% totally vaccinated and over 87% having acquired the primary dose, many of the instances attributable to Omicron could also be gentle, thus not being examined. A major quantity of people that have been vaccinated may need been beforehand contaminated throughout the lethal second wave. This mixture of an infection plus vaccination produces hybrid immunity, which is extra protecting than simply vaccination or an infection alone. This may very well be another excuse why instances in the neighborhood may need been missed.
One of the primary Omicron optimistic instances detected in India on November 22 was a medical physician in Bengaluru who had no journey historical past or contact with any worldwide passenger. This means that the opportunity of the variant already being current in the neighborhood can’t be fully dominated out. “That [case] is certainly evidence for some degree of community transmission, since there is no apparent connection to a case of international travel. However, not all such infections will necessarily lead to an explosion in cases and it is possible that this was a one-off event,” Dr. Menon says.
“I personally think it is just a matter of time till we see Omicron cases rising, perhaps by January. There is some level of protection, one assumes, from the fact that many Indians have sustained a recent Delta infection and many are now vaccinated as well. This may lead to overall milder cases, which might be one reason why we have not seen any sizeable jump in hospital admissions,” he provides.
Kerala well being secretary Dr. Rajan Khobragade says that apart from sequencing optimistic instances of worldwide passengers, Kerala will sequence optimistic instances from big clusters and superspreader occasions to rule out the Omicron variant within the State.
But Dr. Menon feels it is perhaps essential to sequence some fraction of symptomatic COVID-19 sufferers throughout the nation to evaluate the presence of COVID-19 and this particular variant within the inhabitants, and in addition take a look at randomly, in search of the presence of Omicron in a fraction of those who take a look at optimistic. “Only then can we assess the extent of community spread,” he says.
