Stemming the onslaught of Omicron

HYDERABAD, TELANGANA, 18/12/ 2021: A health worker inoculates a man with dose of Covishield vaccine against the Covid-19 coronavirus during GHMC’s free mega vaccination drive in Hyderabad on Saturday, December 18, 2021. Photo: NAGARA GOPAL / The Hindu

HYDERABAD, TELANGANA, 18/12/ 2021: A health worker inoculates a man with dose of Covishield vaccine against the Covid-19 coronavirus during GHMC’s free mega vaccination drive in Hyderabad on Saturday, December 18, 2021. Photo: NAGARA GOPAL / The Hindu

After the massive second wave of COVID-19 caused by the Delta variant, India has been in the endemic phase. This is the much-awaited respite that permits further relaxation of curbs on social interactions and reopening of all educational institutions. As these are implemented in different States at different paces, India now faces the threat of an Omicron wave. Some experts seem to believe that there will not be another wave since the Omicron variant is not causing severe disease in other countries. We cannot predict whether extensive transmission of Omicron will cause a wave. For some four months there was unrestrained circulation of the Delta variant before it showed up as the second wave of disease. Omicron will take less time as it spreads faster. We did not flatten the Delta wave curve with vaccination; we must use vaccination now to block another wave. The risk of a disease wave may be small but it is not zero.

The case for booster doses

Our best defence against Omicron is to bolster population immunity with vaccination. Omicron tends to evade immunity induced by infection or two doses of the vaccine. But the evasion is partial. The higher the antibody level, the better the protection. A recent report of cross-protection showed that all convalescent sera neutralised Omicron, albeit with low titres. A booster shot of a vaccine raises antibody levels at least an order of magnitude higher than those induced by infection or two vaccine doses. That is why many countries are providing booster jabs. What we believe is that the entire population should be vaccinated with two doses, including children (as Omicron causes more infection in children than Delta), and booster doses provided for those who had their second dose six or more months earlier.

Policymakers argue that Omicron will not cause serious illness, as initial trends suggest elsewhere, and so booster doses are unnecessary now. Everyone agrees that Omicron is spreading faster than even Delta. These observations must be seen against a background of the high prevalence of immunity in the population. Omicron’s true virulence in the non-immune population will be known only in due time. Should we therefore decide against booster doses now? Do we not know that booster doses will inevitably be necessary tomorrow, if not today? So, why not administer them earlier since we know that boosted immunity lasts longer?

All those who have followed COVID-19-appropriate behaviour and stayed safe may not be spared infection from Omicron. Diabetics; cancer patients; patients with autoimmune disease, chronic cardiovascular, renal or liver diseases; those who have had organ transplants; and those aged 60+ with immune senescence face the risk of disease. The World Health Organization (WHO) and Centers for Disease Control and Prevention advise a third dose for them to ensure adequate immunity. Apart from these categories of people, healthcare workers occupationally exposed to the virus are a priority. However, everyone who has taken two doses will need a booster sooner than later. If we wait for evidence on how many cases of serious disease and hospitalisation Omicron can cause, we may be too late in protecting these segments with the simple measure of administering a booster.

We know that breakthrough infection in two-dose recipients is common with Omicron. They will act as links in the chain of further transmission. We must slow down virus circulation and this can be achieved only by increasing the proportion of people who are adequately immunised.

Is there evidence that booster doses will protect us? Studies show that 70% of immunocompromised individuals show rapid increase in neutralising antibody titre with a booster dose. A booster dose with an mRNA vaccine protects well against symptomatic disease caused by Omicron. Will vaccines in India boost immunity against COVID-19? We must assume they do, but we also need to investigate this for confirmation. All these efforts should run in parallel. It is a well-accepted principle in vaccinology that booster doses consistently and exponentially enhance immunity. To face Omicron, which is highly transmissible and has a tendency to evade low levels of immunity, we must act now. Waiting for evidence is unwise – while anticipating evidence, we should offer boosters.

A second argument against booster doses is that India should share its vaccines with countries where the vaccination programme is lagging instead of administering booster jabs for its own citizens. The government has primary responsibility towards the Indian population. And India is doing its best to fulfil its obligations to low-income countries — more so than many developed countries.

Some argue that the two-dose vaccination programme for the entire eligible population will suffer if booster doses are administered. These two objectives are not in competition. Booster doses are to be administered after a six-month interval after the second dose. There is no reason why the two-dose programme and the booster programme cannot go hand in hand, especially since vaccine supplies are sufficient.

When responding to a crisis, decisions must be made quickly, with foresight, integrity and humanity. To wait for firm evidence to emerge before taking action or to take hasty, wrong decisions will entail a price. Foresight shows the middle path. WHO is reluctant to advise boosters now as its duty is to advocate vaccine equity. We must rely on our own integrity to enable us to balance our immediate needs and altruistic allocation for other countries.

Immunity is a spectrum ranging from protection from severe disease and death, to preventing even the mildest disease, to preventing infection itself. When we consider the nation’s health, our humanity demands that we protect the vulnerable from risk of severe disease and death. Retarding virus circulation and even inhibiting asymptomatic infections becomes a priority. This is the rationale for offering booster doses.

On child vaccination

It is urgent that we vaccinate children, already back in schools, as a defence against Omicron. The experience in other countries warns us that children without immunity get infected causing disruptions in school and transmission in households. Even children with asymptomatic infection will carry the virus home. Further, if we vaccinate children in a well-organised school-based vaccination programme, we will reduce the size of the potential ‘virus reservoir’ of that unvaccinated population segment. We need to fast-track approval processes for Emergency Use Authorisation for children. That will enable the next step of recommendation by the Technical Advisory Group on Immunisation. One vaccine manufacturer has made an intranasal vaccine in India. The need for it is now. Hence, its evaluation by a regulatory agency must be fast-tracked in an emergency mode.

How do we ensure that those who are immunocompromised get the booster dose? It is time that the vaccines already approved with the EUA are licensed quickly. This will enable physicians to assess the risk in individual patients and counsel them — thereby ensuring that those in need of booster jabs get them quickly.

We may be right in assuming that Omicron is relatively harmless. But we may also be wrong and the price we will pay then could be hefty. Instead, if we assume it to be ominous and take all precautions even before evidence clarifies the true picture of Omicron’s behaviour, society can go back to pre-COVID normalcy sooner.

T. Jacob John is retired Professor of Clinical Virology, CMC Vellore, and M.S. Seshadri is Medical Director of the Thirumalai Mission Hospital, Ranipet, Tamil Nadu

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Printable version | Aug 9, 2022 10:04:51 pm |