How infectious is the Omicron variant?
The infectiousness of a variant depends on its transmissibility and its capacity to evade human immune systems. The sheer number of mutations in the spike protein of the Omicron variant affects both these properties, making Omicron 3-5 times as infectious as Delta, and also more capable than Delta for evading the immune defenses derived from the previous infection and/or vaccination.
As per WHO, it has a doubling time of 1.5-3 days. If you remember the chess lore of a king donating one grain in the first square, two in the second, four in the third and so on, you would get an idea of how rapidly it can spread. Even in India, we are seeing a case doubling every 3 days. At this pace, we may see around 4-5 lakh daily cases by Republic Day with Omicron overpowering the Delta variant in the next 4 weeks!
What should we do?
Most importantly, Omicron doesn’t transmit in ways differently from the earlier variants. Those who are vaccinated or don’t have any symptoms can also spread Omicron even when they do not know that they are carrying the virus. This means that our best preventive measures -‘universal’ masking, physical distancing and improving ventilation are more important than ever before. This also means that excessive focus on surface disinfection is not needed.
Avoiding large gatherings with unmasked interactions and non-essential travel for the next 4-6 weeks is going to be very crucial to slow down the surge.
How severe is Omicron?
Research in England, Scotland, and South Africa has found that Omicron causes milder illness than earlier variants, with the risk of hospital admission being lower (about 70% lower as per South African data). In South Africa, there was no significant spike in deaths despite the rapid spike in cases. South Africa’s optimistic data may not necessarily mean that Omicron is intrinsically less aggressive. The milder course is perhaps largely due to pre-existing immunity in these populations due to prior infection or vaccination.
What is not yet clear is whether the severity of infection is mild even in those who are unvaccinated and have not been previously infected with Covid. Given that the seroprevalence of Covid-19 antibodies in several Indian cities and towns was near 90% and with over 60% of our eligible population being completely vaccinated, we may cautiously hope that the upcoming third wave may not be quite as catastrophic. But those who are not immune will continue to remain at risk of hospitalizations and death.
What should we do?
Percentages do not give the complete picture when the number of cases increases rapidly. While the risk of severe disease or death may be relatively low for any individual, the threat at the population level may still be quite high due to the sheer number of potential infections straining our healthcare system and the death toll would then exponentially increase. How we prudently use the health care facilities will be key in keeping the death rate low.
Over 90% of the cases will be mild and can be easily managed at home. Despite this understanding, we are already seeing ‘fear admissions’ in hospitals. This artificially strains the system by making beds unavailable for those who need it most and for those with other emergent illnesses, a phenomenon we witnessed during the second wave. We should not be repeating this mistake again.
On the other hand, state-driven curbs will have to be based on the number of severe infections and not merely the total cases seen. Monitoring the oxygen requirement and available ICU bed status in a city/state may have to be the new yardstick to gauge the true burden on the healthcare system.
What is the role of vaccination and boosters?
Deciphering true vaccine effectiveness for newer variants in the real-world scenarios may take several months. Data from other countries like the UK has shown that two Covid jabs do not offer strong protection against symptomatic infection from Omicron. But vaccine effectiveness appears to be maintained against severe disease even when antibody levels seem to be waning. Recent data from South Africa showed a 70% protection from hospitalization after two doses of the mRNA vaccine, compared to 93% against Delta. This is probably because while the variant can evade pre-existing antibodies and cause infection, it may not be able to escape the unmeasured but powerful memory T- cell responses that prevent severe disease. Those who get their booster remain up to 70% protected even against symptomatic infection.
What should we do?
Will monoclonal antibodies and direct antiviral drugs be effective against the Omicron variant?
There are two categories of drugs that continue to have evidence of some efficacy in Covid-19.
Monoclonal antibodies (MAbs) are artificially manufactured antibodies that are injected and target a region on the spike protein to negate the virus. Unfortunately, these MAbs have little or no activity against Omicron because its highly mutated, and should not be used. The only possible exception is a drug called sotrovimab, which is anyway not available in India as of now.
The other class of drugs are anti-viral drugs. Omicron-specific data on the effectiveness of these including remdesivir and the recently approved molnupiravir is not yet available though it is not expected to be affected drastically. Although the approval of Molnupiravir may look exciting in light of the current rise in cases, analysis of the full clinical-trial data showed lower-than-expected efficacy. The study found benefits only in unvaccinated individuals. The protection from Delta or Omicron variant remains uncertain.
What should we do?
The management of Covid-19 has seen a roller coaster ride with the inclusion and disposal of multiple therapeutic options right from Hydroxychloroquine, Favipiravir and plasma therapy to antibacterial and anti-worm drugs. Almost 2 years into the pandemic, it is time that our treatment protocols be driven only by scientific evidence and not by ‘what we think works well’ or ‘what others’ prescriptions look like’.
After all, every drug has some side effects and it should only be prescribed if the expected benefit outweighs that risk. This is especially when over 90% of Covid patients will need either no drugs or just symptomatic treatment like a decongestant or paracetamol. The use of multidrug cocktails and expensive therapies should be discouraged.
How will Omicron span out in the pediatric population?
The latest coronavirus surge sweeping several countries has produced a worrisome rise in hospitalizations among children, double that among adults in some countries. A lot of this has got to do to with the lack of pediatric vaccination. Hospitalization figures can be misleading because they sometimes include all children who have tested positive for the Covid-19 upon admission and not necessarily those who are symptomatic for Covid.
Some of the recent increase in admissions in these countries was complicated by the spread of wintertime viruses in medically fragile children.
Preliminary reports suggest that, similar to adults, Omicron appears to be causing milder illness in children compared to Delta, and that vaccination offers protection against hospitalization if available.
What should we do?
New variants like Omicron are a reminder that the COVID-19 pandemic is far from over and following Covid appropriate behavior consistently is ‘human’ly impossible. The real end to this pandemic will be when we can go back to the no-masking days.
And this will only happen when vaccines are available to all countries with all people taking their vaccines whenever they become available. Clearly, the battle against Covid cannot be fought by a country in isolation. Until then, let’s get back to square one and do all we can to flatten the wave this time around!