Every time someone in India (politician, media anchor or scientist) declares emphatically that we have attained herd immunity and no longer need to fear the virus, SARS-CoV-2 serves a reminder that it has new tricks to reveal. It happened before Alpha seared us and then again before Delta scorched us. Arrival of the Omicron variant follows fresh claims of herd immunity, which led to abandonment of COVID-appropriate behaviour in many parts of India during the festive season of October-November 2021. It is ironic that those who claimed a cast iron protection for the people of Delhi, with 97 per cent antibody test positivity in the sixth serological survey in October 2021, are among the first to demand a ban on flights from any country reporting the new variant. What a confession of vulnerability, despite the bravado!
A misplaced belief that India had seen the end of COVID was based on the assumption that most Indians have acquired immunity against the Delta variant during the devastating second wave, with the faster pace of vaccination thereafter providing additional protection. This optimistic view did not factor in possible emergence of new variants from unvaccinated persons in India or their entry from other countries. Hence the consternation, bordering on panic, that has been on display when Omicron emerged most unexpectedly.
There has been much speculation about the infectivity, virulence and immune evasion capacity of Omicron, even as data are scant at present and studies have just begun. This is reminiscent of Mark Twain’s wry remark “there is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.” While virus variants are no trifling matter, conjectures are running far ahead of available evidence. While public health prudence and political sagacity demand that we take protective action even on the basis of incomplete information, we should not rush to rash conclusions about how dangerous the new variant would be to infected individuals, populations at risk within countries and the interconnected global community. Scientific information and analyses are still emerging.
Understanding Omicron
It is likely that Omicron is highly transmissible from person to person. This is based on the mutations which it shares with Delta and several added new features. These give it higher replication rates in the upper respiratory tract, especially the throat. It has a greater ability to grip and attach itself to human cells using many of its 32 spike protein mutations to cling to the ACE2 receptors on cell surface. The speed with which it appears to have spread among people in the Gauteng province of South Africa and the detection of copious viral presence in the sewage water of Pretoria indicate that the virus spreads fast within a country. As the UK and Europe are adding to the daily list of new locations where cases are emerging (Portugal and Scotland being among the recent ones), global spread is attesting to high early transmissibility. It is unclear, however, whether it will displace the dominant delta from many parts of the world. The Formula One race for the variants is now on!
In contrast, more mutations do not by themselves indicate increased virulence. The principal objectives of mutations, as the virus tries to retain its presence in a world that is combating it, are to become more infectious and better at evading the immunity that has been conferred by vaccines or previous infection. It has no survival advantage in killing most of the humans it infects, if the supply of unprotected people is dwindling. Indeed, early reports from South Africa report no deaths so far and only mild symptoms not requiring hospitalisation. We need more information, from larger case series around the world, but early indications are of lower virulence as a trade-off for increased infectivity. That is consistent with the evolutionary biology of respiratory viruses.
Immune evasion or escape is of great concern, as it might lead to more ‘breakthrough’ infections in the fully vaccinated and ‘re-infections’ in those who had recovered from illness caused by earlier versions of the virus. As we know by now, currently available COVID vaccines do not prevent infections by the virus. They prevent the infections from leading to severe illness resulting in hospitalisation or death. As transmission rates increase in community settings, reinfections and breakthrough infections too will rise but will mostly result in mild illness.
Most of the vaccines used around the world are ‘spike protein’ specific. The mRNA and virus-vector vaccines have been designed to produce the spike protein in our bodies, so that a strong immune response can be generated against it. Since it is this protein which is used by the virus to enter our cells, antibodies generated against it can immobilise the virus in the blood stream, before it can enter the cells. Omicron’s shape-changing spike protein mutations may make it unrecognisable to the spike-specific antibodies. While there is a scientific basis for this concern, previous variants like Delta showed a diminished but still effective response to the current vaccines. Vaccine manufacturers are now preparing to tweak their vaccines against Omicron’s spike protein configuration.
An inactivated virus vaccine, like Covaxin, presents a larger array of viral antigens to the human immune system. The broadband immunity it evokes is not spike protein specific and, therefore, may be better able to counter the variant. This still needs to be confirmed in laboratory neutralisation studies. The situation may be similar for persons who were infected with earlier versions of the virus. They too would have immunity not only against the surface spike protein but also against other antigens that lie deeper in the virus. So, Omicron may be able to evade the anti-spike antibodies but will still yield to the antibodies against the other antigens as well as the cell-mediated component of the immune response.
Fight the Virus as Team World
To prevent infections in the first place, we need to both boost our natural immunity and adopt COVID-appropriate behaviours. This is an old refrain but needs to be repeated as people revert to unsafe behaviours when they feel that the danger is absent or minimal. Nutritious diets (rich in fruits, vegetables, nuts and protein), moderate physical activity, adequate sleep and breathing exercises can bolster innate immunity. Masks have to be worn outdoor and in crowded indoor locations. Homes, offices, shops and transport should be as well-ventilated as possible. Hand hygiene must be practised.
Travel bans may temporarily slow down but not prevent spread of the virus globally. They are counter-productive in many ways. We need to have strong entry point surveillance, effective identification of cases and contacts through appropriate testing accompanied by higher levels of genomic analyses of positive samples and gearing up of our health system for a more intense level of pandemic response. Vaccination coverage too must increase, to complete two-dose universal adult vaccination, followed by boosters for vulnerable adults and initiation of child vaccination for vulnerable children.
COVID does not let you forget that health is central to our development agenda. It has just sent another teacher to give us fresh lessons and also to test our retention of previous learning. It is up to us to prove that we are good pupils who can apply past knowledge and quickly adapt to new instructional methods. Do not play hooky in crowded streets, screaming from unmasked faces that the virus has been driven away. We can and must pass this test, not just as Team India but as Team World.
Professor K. Srinath Reddy, a cardiologist and epidemiologist, is President, Public Health Foundation of India (PHFI). The views expressed in this article are those of the author and do not represent the stand of this publication.
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