Omicron: Sound Alert Not Alarm
Too little is known as of now to presume this variant will be worse than Delta
K Srinath Reddy
29.11.2021
Covid virus variant B.1.1.529 had the shortest wait time for acquiring a Greek name, from the time of its first reported arrival into the world. Initially identified in Botswana and later confirmed by South Africa, it has been labelled as a variant of concern (VOC) by the World Health Organisation which named it Omicron. By November 26, it was also reported from Hong Kong, Belgium and Israel. By the next day, Omicron was detected in more countries, including two cases in the UK which had announced a ban on flights from African countries.
Several other countries too have banned flights from Africa and Hong Kong. It is not clear whether the ban will be extended to more countries that now have Omicron infected persons, such as the UK itself. It is also unclear how effective travel bans are, given the experience with the Alpha and Delta variants which slipped through such restrictions. The South African health minister has protested that his country is being unjustly penalised for efficiency in testing and honesty in reporting The heightened concern is linked to the large number of new mutations that Omicron has acquired, especially in the spike protein which the virus uses to enter the human cells. It was reported that these provide Omicron a greater ability, than the currently dominant Delta variant, to bind to the human ACE 2 receptor which opens the door to the interior of the cells. After entry, the virus uses human genetic material to make many copies of itself. They can then infect other humans, to continue the chain of transmission. Through these mutations, Omicron appears to have acquired features that give it greater infectivity.
Is the new variant to be feared more than the Delta variant? Will it dethrone Delta in a militant march around the world? Apart from higher infectivity, will it have greater virulence than Delta or other variants? Will it evade the immunity provided by currently available vaccines? Will it bypass the immunity acquired through natural infection with the ancestral virus or any of the variants that emerged later, including Delta?
While these are legitimate concerns, it is too early to definitively answer any of these questions. Data are still being gathered from the populations of different countries to assess infectivity and virulence and laboratory studies are being conducted to evaluate the ability of the variant to evade previously acquired immunity, whether from vaccines or natural infection. Statements from scientists are currently strewn with phrases like ‘may’, ‘could’ and ‘possibly’ as they await definitive evidence. However, many sections of the media and politicians of several countries have already assumed the worst and proclaim Omicron as the most dangerous coronavirus yet to emerge since Covid debuted in Wuhan.
It was breathlessly reported that two persons in adjoining rooms were infected, as proof that Omicron spreads via aerosols, while it is by now well accepted that the Covid virus had both aerosol and droplet modes of transmission all through the pandemic.
It is possible but not necessary that a variant which possesses more spike protein mutations will have spreading and staying powers that can conquer the world. The Beta variant, first reported from South Africa, was greatly feared because of mutations that gave it greater prowess of immune escape.
However, that variant has not spread wide to become the global threat it was feared to be. Neither did Lambda or Delta Plus variants, which too failed to displace the Delta. While Omicron might achieve greater success than other competitors to Delta, it still needs to demonstrate that its bite is as bad or worse than its bark.
Will the variant make all of the currently available vaccines useless for our defence? The most widely used Covid vaccines in the world, made on either mRNA or virus vector platforms, have exclusively targeted the spike protein antigen. It is likely that the virus has evolved numerous new spike protein mutations to evade the immune response they evoke. However, reduced efficacy does not mean absent immunity. It is possible that a considerable degree of protection against severe disease and death may still be offered by the vaccines.
Other vaccines, directed against multiple viral antigens through the use of an inactivated virus, may not be stymied by spike protein mutations. A broader band of immunity, produced by them, may help to capture and quell the masquerading mutant. We still need data to test these possibilities.
The debate on variants should not be confined to vaccines alone. We must recognise that masks effectively protect against transmission of the virus, including all its variant forms. Ventilation too helps in reducing transmission. Crowding is fraught with danger of a super-spreader effect. We can go on tweaking vaccines as new variants emerge but, unless we exhibit discipline to curb transmission in a sustained manner for several months at a stretch, the virus will find enough human bodies where it can experiment with new mutations.
It is time we stop periodically celebrating the presumed arrival of herd immunity and get down to the task of closing the channels of transmission, even as we work on developing vaccines and drugs against variants. Apart from entry point screening, which will only be partially successful because of negative RT-PCR tests early after infection, we should strengthen follow-up of entering travellers and trace contacts of those diagnosed even later.
The new mantra should be MVVT (masks, ventilation, vaccines and testing) rather than LTBP (lockdowns, travel bans and panic).
The writer, a cardiologist and epidemiologist, is President, Public Health Foundation of India (PHFI). Views are personal
It is possible but not necessary that a variant which possesses more spike protein mutations conquers the world. The Beta variant was greatly feared because of mutations that gave it greater prowess of immune escape. However, it has not become the global threat it was feared to be
