Is the Omicron Variant Likely to Be Deadly: Rethinking the Impact of BA.4 and BA.5

The rise of new Omicron subvariants, BA.4 and BA.5, has raised concerns among epidemiologists and the general public. These subvariants, first discovered in South Africa, have shown a significant increase in cases, prompting further investigation into their transmission dynamics and potential impact on the pandemic.

The Rapid Rise of BA.4 and BA.5

Published in Nature, these subvariants have been detected in numerous countries, appearing to spread faster than earlier circulating subvariants, mainly BA.2. However, their impact on public health has been less severe, indicating a growing immunity within the population.

Biological Characteristics and Spread Mechanisms

BA.4 and BA.5 share genetic similarities with the earlier Omicron strains but possess unique mutations, such as L452R and F486V, in the viral spike protein. These mutations may alter the virus's ability to bind to host cells and evade immune responses. Recent studies suggest that these subvariants may be able to infect those previously immune to earlier forms of Omicron, leading to a resurgence in cases.

Global Impact and Local Variations

The effects of BA.4 and BA.5 vary significantly across different regions. In South Africa, despite a noticeable rise in cases, hospitalizations and deaths remained relatively stable. Conversely, in countries like Portugal, with higher vaccination rates, the impact was more significant. Demographics and immunity profiles play crucial roles in determining the severity and spread of these subvariants.

Effectiveness of Vaccines and Antibodies

Laboratory studies have indicated that antibodies from vaccines may be less effective against BA.4 and BA.5 compared to earlier Omicron variants. This suggests that even vaccinated individuals could experience multiple infections, highlighting the importance of booster shots and continued vaccine updates.

Future Variants and Immunity Evasion

The emergence of new subvariants indicates the ongoing challenge in creating a comprehensive immunity against evolving SARS-CoV-2 strains. Researchers suggest that further mutations could continue to evade existing immunity, necessitating continuous monitoring and adaptation of diagnostic and treatment strategies.

The rise of these subvariants underscores the evolving nature of the pandemic and the need for a flexible and adaptive approach to public health measures. As the virus continues to evolve, understanding and responding to these subvariants will remain critical in controlling the spread and minimizing their impact on public health.

Conclusion

While the Omicron BA.4 and BA.5 subvariants pose new challenges, ongoing research and adaptive policies offer hope for mitigating their impact. The current data suggests that despite their rapid spread, these subvariants do not yet represent a significant increase in mortality or hospitalization rates, provided there is a significant level of immunity within the population.

References:
1. Cao Y. et al. Nature. 2022.
2. Khan K. et al. Preprint at medRxiv. 2022.
3. Kimura I. et al. Preprint at bioRxiv. 2022.
4. Reynolds C. J., et al. Science. 2022.