Taking the booster dose enhanced the protection against severe COVID-19 breakthrough infection due to the Omicron variant, even though the natural immunity declined after the primary doses, suggests a study published in the journal Science.¹

In this study, the researchers tested seven Covid vaccines for their efficacy against the new Omicron sublineages, including the original Wuhan strain (G614). These vaccines were Pfizer, Johnson & Johnson, Moderna, AstraZeneca, Novavax, Sinopharm and Sputnik V. They also examined the effect of the mutations in the spike protein on the virus.

Results showed enhanced binding of BA.1, BA.2, BA.2.12.1, and BA.4/5 sublineages to the ACE2 receptors and marked decline of plasma neutralizing antibodies produced either by the natural immunity following infection or vaccine induced when compared to the ancestral strain. Also, the Omicron BA.5 was able to bind six-times more strongly with the ACE2 receptor than the ancestral Wuhan strain. However, administration of the booster dose, heterologous or homologous, increased the neutralizing antibody titers and activity of all vaccines tested against the Omicron sublineages.

The SARS-CoV-2 virus has evolved several times during the course of the pandemic leading to more infectious and immunoinvasive variants. The latest variant of concern is the Omicron, which evolved further into several sublineages including the BA.1, BA.2, BA.2.12.1, BA.4 and BA.5. Of these, the BA.5 is fast becoming the most prevalent sublineage. According to this study, it has maximum immune-evading properties among all Covid-19 variants. While this study demonstrates the increasing immune escape potential of the Omicron subvariants, it also shows that the booster may be protective against severe infection. Hence, all eligible persons must take their precaution dose to enhance their protection.  Now is also the time for the second generation Covid vaccines.

Reference

1. John E Bowen, et al. Omicron spike function and neutralizing activity elicited by a comprehensive panel of vaccines. Science. 2022 Jul 19;eabq0203. doi: 10.1126/science.abq0203.