When a coronavirus variant is deemed a ‘variant of concern,’ one of the first things scientists investigate is whether or not it can evade vaccine-induced immunity. Of all the previously dominant variants, including Delta and Beta, studies revealed that fully vaccinated individuals do have a considerable amount of protection with both jabs.
The case however, has not been the same with the Omicron variant. Since the beginning of its growth, this strain has been constantly referred to as the ‘vaccine-resistant’ variant. Scientists are yet to solidify this claim with proper studies, but latest estimates from the Scientific Advisory Group for Emergencies (SAGE) have provided some solace during this uncertain time.
According to their modelling, which was published and presented by the London School of Hygiene and Tropical Medicine, a full course of the Pfizer vaccine (two doses) was estimated to reduce the risk of hospitalisation and death by the Omicron variant by 83.7%. Meanwhile the AstraZeneca vaccine decreased the chances of severe infection by 77.1%.
To compare, the results for efficacy against the Delta variant were 96% and 93% to 95% respectively.
After studying antibody activity, researchers also found that the immunity provided by both brands of vaccines do wane over time. The paper projected that the AstraZeneca vaccine ‘provided 36.1% of protection, while Pfizer provided 46.7% from getting symptomatic Omicron infection after six months,’ reported Mail Online.
Room for trouble
This suggests that the strain isn’t completely vaccine-resistant, but fully vaccinated people are still more vulnerable to infection, especially if they haven’t received a booster vaccine. Microbiologist Dr. Simon Clarke from Reading University told Mail Online that even a slight ‘drop’ in vaccine efficacy can still have catastrophic effects. He said:
Nobody ever expected Omicron to wipe out vaccine efficacy; it was just a drop that was expected — and that in itself can do enough damage.
Authors of the study have also reiterated the same, saying that the Omicron variant has the 'potential to cause substantial surges in cases.' They added:
These results suggest that Omicron has the potential to cause substantial surges in cases, hospital admissions and deaths in populations with high levels of immunity, including England.
The reintroduction of additional non-pharmaceutical interventions may be required to prevent hospital admissions exceeding the levels seen in England during the previous peak in winter 2020–2021.