Does India Needs Booster Dose To Neutralise Omicron Threat: London Study Hints Big

With recent studies from the UK clearly hinting at a lower infection rate among the individuals with triple doses than ones having double shots, India has to decide on going for a booster dose sooner than later.

The study by MRC Centre for Global Infectious Disease Analysis, Jameel Institute and Imperial College London) hints at a grave scenario. It found Omicron infection higher in vaccinated individuals. But the infection risk is lower for individuals who have taken triple shots.

"We found a significantly increased risk of an Omicron case compared to Delta for those with vaccine status Astra Zeneca or AZ (Known as Covishield in India) 2-plus weeks (2+w) post-dose 2 (PD 2), Pfizer 2+w PD2, AZ 2+w post-dose 3 (PD3) and PF 2+w PD3 vaccine states with hazard ratios of 1.86, 2.68, 4.32 and 4.07, respectively, where PD3 states are categorised by the dose 1/2 vaccine used," the study observed.

Moreover, the study shows Pfizer proving more effective against Omicron than Astra Zeneca (know as Covishield in India).

PCR Test Failing?

As per the UK study, Omicron re-infection risk is 5.41 times that of Delta. Moreover, Omicron may escape the RT-PCR test. The reason is re-infections carry higher Ct values, as a consequence exhibit a higher rate of random PCR target failure.

"To assess the impact of Omicron on re-infection rates we relied on genotype data, since SGTF (S-Gene Target Failure) is associated with a higher observed rate of re-infection, likely due to re-infections typically having higher Ct values than primary infections and therefore being subject to a higher rate of random PCR target failure," the study observed.

The study further says, "Controlling for vaccine status, age, sex, ethnicity, asymptomatic status, region and specimen date and using conditional Poisson regression to predict re-infection status, Omicron was associated with a 5.41 fold higher risk of re-infection compared with Delta. This suggests relatively low remaining levels of immunity from prior infection."

How Omicron Spreads Faster?

As per a recent study by Hong Kong University, the new mutant replicates 70-times more within 24-hours in tissues that line the airways (especially the upper air tracts or bronchus).

"Omicron replicates itself 70 times faster in tissues that line the airway passages within 24-hours of infection. For which, the mutant speed up person-to-person spread," the study observed.

Why Omicron Is Less Severe?

A study by the Hong Kong University reveals that the Omicron variant multiplies 10 times more slowly in the lungs than the original kind of the coronavirus (Wuhan Virus). This is what made the new mutant less severe, the study added.

However, Dr Michael Chan Chi-wai, Associate Professor of School of Public Health and Principal Investigator, Centre for Immunology and Infection (C2i), Hong Kong Science and Technology Park (HKSTP) has served a warning.

"It is important to note that the severity of disease in humans is not determined only by virus replication but also by the host immune response to the infection, which may lead to dysregulation of the innate immune system, i.e. “cytokine storm”,’ said Dr Chan.

He further added that by infecting many more people, a very infectious virus may cause more severe disease and death even though the virus itself may be less pathogenic (means less virulent).

"Therefore, taken together with our recent studies showing that the Omicron variant can partially escape immunity from vaccines and past infection, the overall threat from Omicron variant is likely to be very significant,’ Chan Chi-wai informed.

Omicron New Symptoms

As per the data released on 16 December by the Covid Symptoms Study, run by the health science company Zoe and King’s College London, the top five symptoms of omicron infection are:

• Runny Nose
• Headache
• Mild to Severe Fatigue
• Sneezing
• Sore Throat

A study of symptoms reported in India shows that some Omicron carriers display fever symptoms.

Omicron Infects Which Age-Group?

As per the data from the UK and South Africa, Omicron infection is seen mostly in the 15-20 years age group.

However, a look at the age-group data of infected individuals in India reveals that the majority of infected belong to the age group of 24-45 years.