Do Vaccines Work against Omicron, is it as Deadly as Delta? FAQs on New COVID Variant Answered
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The decision to start vaccinating children aged 15 and above in India is prescient as the new variant—Omicron—of the now very familiar COVID-19 is seen to significantly affect children. COVID-19 cases among children are rising again in the US, with new pediatric patients up nearly 24 per cent over the previous week. A South Africa study found that children had 20 per cent higher risk of hospitalisation compared to earlier variants. Another study showed that Omicron is currently more concentrated in the young adult age group (20-29) compared to Delta. Younger people, with less vaccine coverage, are understandably a natural niche for spreading mutated and adapted SARS-Cov-2 like Omicron. Historically, this is how viruses evolve to find an equilibrium with the host.
Omicron has spread to 110 countries, fast becoming the dominant infection in many of them—72 per cent of all COVID-19 cases in the UK and 76 per cent in the US. Omicron is expected to replace Delta and become the dominant variant in many other countries in Europe at the start of 2022 (WHO). The lightning speed at which it is spreading has forced scientists to anoint it the ‘fastest spreading infectious disease known to man’. Based on a CDC analysis, US federal health officials recently warned that there might be a massive wave of COVID-19 infections as soon as January. Delta is likely to continue as the dominant variant for now. A combination of these two variants riding over flu and winter may be particularly challenging for communities not covered fully by vaccination.
Two years of grappling with the pandemic have equipped us with a better understanding and responsiveness to the new threat. There is, in a way, nothing new we need to do except reiterate the sustained need to comply with COVID-19 behaviours, get vaccinated, do everything to save our loved ones and us from getting infected, and for the rest, we have science to inform what changes. Let us attempt to answer some common questions on the new variant in the light of information we have today with the caveat that, like the earlier variants, it will take us more time to comment conclusively on the long-term effects.
The Good and the Bad News on Omicron
We have both good news and bad news on the new variant for the short term. Let’s digest the bad news first. Whether acquired through a previous infection or one or two doses of vaccines, existing immunity is not very effective against preventing Omicron. For Pfizer BioNTech-Comirnaty or AstraZeneca-Vaxzevria (known as Covishield in India) vaccines, vaccine effectiveness against symptomatic infection from Omicron ranges between 0-19 per cent following two doses and between 54-77 per cent after a booster dose. Protection against reinfection by Omicron after a past infection may be as low as 19 per cent. Studies show that reinfection rates are at least three times higher for Omicron than Delta.
Another study from South Africa estimates that Omicron is 36.5 per cent more transmissible than Delta and that Omicron erodes the population immunity accumulated from prior infection and vaccination. Also, the household attack rate of Omicron is about 16 per cent compared to around 10 per cent for Delta, meaning there is a higher chance of transmission to family members by both infected symptomatic and asymptomatic persons. Given the potential for immune evasion and faster spread, we must brace ourselves for a third wave of COVID-19 in early 2022. The signs of rapid increase of Omicron cases are already manifest in metros like Delhi and Mumbai.
Now, the good news and there are many. Getting boosted with vaccines considerably enhances protection against Omicron (70-80 per cent effectiveness in severe disease, hospitalisation and death), with milder and self-limiting symptoms like cold and cough among the fully vaccinated, slightly rougher for the partially vaccinated but again milder than Delta variant. Early data from South Africa, the United Kingdom and Denmark suggests a reduced risk of hospitalisation for Omicron by as much as two-thirds compared to Delta. The UK Health Security Agency found that those stricken with the Omicron variant are 31-45 per cent less likely to go to an emergency room and 50-70 per cent less likely to be admitted to a hospital than those infected with the Delta variant. We still need to confirm if this is due to acquired immunity or the less severe disposition of Omicron.
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The second good news is that the existing multi-target PCR tests can detect the infection by Omicron. We may need to modify some tests which are specific to Delta and do not target multiple sites of the virus due to the high number of mutations in Omicron—30 to 50 in number—with more than half of these on the spike protein, the target of PCR tests. Studies on the relative sensitivity of Rapid Antigen Tests (Ag-RDTs) are ongoing. So far, statements from manufacturers indicate that most of the currently used Ag-RDTs, including two WHO-approved (Emergency Use Authorisation) tests, have retained their ability to detect SARS-CoV-2 variants, including Omicron.
The third good news is that existing therapies—Corticosteroids and IL6 Receptor Blockers—work against Omicron, although the same cannot be said for monoclonal antibody therapy. Monoclonal antibodies will need to be tested individually for their antigen binding and virus neutralisation in cases of Omicron infections. We need more data on this front.
Symptoms of Omicron are also shown to be mild, anecdotally. CDC reports that cough, congestion, scratchy throat, runny nose, and fatigue appear to be prominent symptoms with the Omicron variant. And unlike Delta, many patients are not losing their taste or smell. The intensity of these symptoms increases in reverse proportion to vaccine status, and severe cases are mainly restricted to the unvaccinated. Omicron has a lesser effect on the lungs than Delta (pneumonia and acute respiratory distress syndrome), and the symptoms are more like those of upper airway infections like bronchitis.
The disease may not be more severe than Delta, yet we expect hospitalisations to increase as cases of Omicron will potentially double every 2-3 days. More hospitalisation means more stress on medical facilities and healthcare workers, leading to more fatalities due to sheer increase in numbers coupled with resource constraints and worn-out health staff. We must, therefore, enhance our preparedness, training of health professionals and response, including oxygen beds and ICU facilities, while accelerating the vaccine coverage and offering boosters to frontline workers.
Vaccines are the Most Potent Weapon
At the individual level, WHO reiterates that the most effective steps are physical distancing, avoiding crowded indoor spaces, wearing a well-fitted mask, opening windows to improve ventilation, keeping hands clean, coughing or sneezing into a bent elbow or tissue, and getting vaccinated when it’s our turn. Booster doses for vulnerable and frontline workers must be offered without delay. For public health authorities, enhanced surveillance with rapid testing and stricter cluster investigations and contact tracing of cases suspected to be infected with Omicron are strongly advised to interrupt chains of transmission.
Vaccines remain our most potent weapon against the spread and sustenance of COVID-19 pandemic. Delta is still the predominant variant against which vaccines are highly effective, and vaccines are likely to have some effectiveness against Omicron, particularly for severe disease, even if performance is reduced compared with other variants. The Government of India is sparing no effort to scale up vaccination through massive outreach and by offering doorstep vaccine jabs under the ‘Har Ghar Tika, Ghar Ghar Tika’ programme. Extending coverage to children is the right step by the visionary Prime Minister of India in stemming the spread of COVID-19, including the new Omicron variant. We, the citizens, must do our part by getting vaccinated and observing appropriate COVID-19 behaviours to keep our families and communities safe. In this endeavour, the 5T model of pro-active COVID management by the Odisha government is also appreciable.
Dr Mrinalini Darswal holds an MBBS degree and is an IAS officer who has worked as Special Secretary, Health; Commissioner Food Safety; Drugs Controller, and Project Director for HIV/AIDS Control Programme for Delhi Government. She is currently pursuing doctoral studies in public health, with a focus on COVID-19, at Harvard. The views expressed in this article are those of the author and do not represent the stand of this publication.
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