By Aditi Madan
The Omicron variant has been identified in many countries around the world as a variant of concern by WHO in the last week of November 2021, given the higher transmissibility but milder disease severity. Its global trajectory depends on two factors, i.e., contagiousness and immune system evasion. Although Omicron is 90 to 95 percent less virulent, but there is still a segment of individuals, particularly older individuals who may get sick. According to epidemiologist, Marc Lipsitch, at the Harvard University, identifying how much transmissibility and immune evasion contribute to variant’s spread will help us to predict how many people are likely to get infected and how rapidly.
South Africa’s Gauteng province where Omicron’s 50 or so mutations were first identified has shown that Omicron is able to cause reinfections as well as breakthrough infections; however, there are signals that the body is able to guard itself better from serious diseases due to T-cell mediated immunity which is helping the body to protect itself from severe disease. The data of the initial 30 days of COVID-19 infections triggered by Omicron, in the Gauteng province, indicate that the infections caused by the variant were more contagious, but not so severe. Early results suggest that South Africa saw less hospitalisations and even lesser deaths than in the past waves, reflecting milder disease severity. But South Africa having a much younger population compared to the world can’t be overlooked as the lack of older and more at risk population getting COVID19 may have disguised the recent variant’s capabilities.
Omicron infected a greater number of children and adolescents, the largely unvaccinated population, which is 17.7 percent (1,151 out of 6,510) when compared with previous waves, i.e., 3.9 percent (306 out of 7,774) for the second wave and 3.5 percent (161 out of 4,574) for the third. And a large number of younger population were admitted in hospital due to low vaccine coverage in children over 12 and in young adults.
Emerging data from different countries points out that the experience of South Africa isn’t an anomaly. Data from most European countries supports higher transmissibility, milder disease severity, and lesser hospitalisations with the latest wave of Omicron variant than the previous variants. Analysis by the UK Health Security Agency highlights that Omicron is less likely to lead to a hospitalisation when compared with the previous wave (the Delta variant), and even if it does, admission won’t surpass levels seen during previous waves.
What’s been observed in South Africa may not be applicable to other countries given the different infection histories and vaccination rates across countries. For instance, US went straight from Alpha variant to Delta and never experienced a wave of infections driven by the Beta variant, while South Africa did, and the exposure to different variants could have altered the US population’s immune responses. However, overall data and evidence from other countries such as South Africa, Europe, and US handling Omicron variant suggest that Omicron is resulting in lesser hospitalisations than previous variants. However, it still continues to be a threat as it’s much more contagious, and may result in more people getting affected, even if the percentage of infected people getting severely sick is lesser in comparison to the last wave.
South Africa’s fourth wave has not been as severe as the earlier waves. South Africa undertook a guarded and thoughtful approach to the pandemic. During the recent wave, no new lockdown measures were announced. However, the country did the complete opposite, by lifting the night curfew and even stopping contact tracing. Based on a closed surveillance of hospitals and their death registers and number of cases, they observed that the virus was behaving in a much different way as people did not land up hospitalised and had very mild impact when compared with the Delta variant. Public health interventions adopted in South Africa such as wearing masks in public, emphasising on ventilation and maintaining physical distance, and being vaccinated helped control the spread of Omicron, and ensured that people did not get infected by any variant emerging in the country. Further, a high rate of prior Delta infections, immunity from vaccination, especially in the elderly, and a less severe variant could be the likely reasons behind this. Given the country’s weak medical and health systems, necessity gave rise to several innovative solutions such as use of zipline drones for transferring samples to testing sites in Ghana; awareness generation through in-flight public broadcasts in Rwanda; converting factories to mask production with set targets in Kenya, etc.
As far as India is concerned, many experts in India believe that the country has hybrid immunity due to which Omicron will be less effective. Amidst surge in Omicron cases in India, majority of the patients are either asymptomatic or with mild disease severity. Further, hospitalisations triggered by Omicron infections are fewer than those triggered by other variants such as the Delta variant, with average time spent in hospital also much lesser.
Given the high transmissibility with milder disease severity of Omicron variant, it is critical to adopt appropriate public health interventions and COVID-appropriate behaviour at all places and by all individuals. While Omicron may be the most immune evasive of the SARS-CoV-2 virus so far, early research shows sufficient protection could be provided through booster or third vaccination shots. Reducing vaccine hesitancy and promoting larger population coverage for vaccination becomes critical to reduce the potential impact of recent wave of Omicron in India. India as a country needs to seize the opportunity to learn from countries having responded to the Omicron variant and combine existing healthcare protocols, technological advancements, and innovation to enhance preparedness and response efficiency.