The new Omicron subvariant
Published in
4 min readMar 28, 2022
The new kid on the block can prove itself to be troublesome.
What is Omicron?
- Omicron is a new variant of COVID that is seen to be more transmissible than its other counterparts.
- The omicron variant has significantly more mutations than previous SARS-CoV-2 variants, particularly in its S-gene, the gene that encodes the virus’s spike protein.
- This makes it more likely to evade the immune response and persist in a host, and has caused surges in COVID numbers in multiple countries.
The new Omicron variant
- The initial Omicron variant was variant BA.1 now has a sister variant, BA.2.
- This raises questions as to whether it has the same potential to cause a surge in cases as the BA.1 variant.
- A recent study shows that mRNA vaccines offer a similar degree of protection against the two strains — although protection against SARS-CoV-2 infection and symptomatic disease wanes within months of a third dose.
- Before exploring this study further, it is imperative to mention that it has not yet been peer-reviewed, and so the findings should not be taken as fact. This is a very new area of research and there are many unknowns.
The study
- The paper involved a massive observational study using vaccination records and SARS-CoV-2 test results from Qatar’s health-care system.
- The basis behind it was to ascertain whether the BA.2 variant can evade vaccine protection.
- Researchers have known for months that the BA.1 subvariant evades much of the protection that mRNA vaccines offer against mild-to-moderate disease.
- Scientists quickly realized that BA.2 spreads more rapidly than BA.1, but it wasn’t immediately clear whether the newcomer would also prove to be more adept at evading vaccines.
- They found that Qatari residents who received two doses of either the Pfizer–BioNTech or Moderna mRNA-based vaccine enjoyed several months of substantial protection against symptomatic disease caused by either BA.1 or BA.2. But protection waned to around 10% after only 4–6 months, meaning that the vaccines prevented only 10% of the cases that would have occurred if all of the individuals had been unvaccinated.
- Protection against BA.2 did not seem to wane any faster than protection against BA.1, and a booster shot brought the protection against symptomatic infection by either subvariant back to 30–60%.
- Surveillance data collected in the United Kingdom reveal a similar trend: vaccine effectiveness against symptomatic COVID-19 is less than 20% for both subvariants 25 weeks or more after a second dose, but rises to roughly 70% 2–4 weeks after a third dose.
- Analysis of data showed that protection against severe disease remained at 68% or higher for at least 7 months, even in people who had only received two vaccine doses, and shot up to over 80% after a booster dose.
- Co-author of the study and epidemiologist Laith Abu-Raddad says that because 70–80% of the pooled cases were BA.2, he suspects that vaccines still offer a high level of protection against severe disease in the face of surging BA.2 levels.
- Abu-Raddad says the results give him hope because vaccines prevent many of the worst COVID-19 cases, even in response to BA.2.
Plans for the future?
- “Another week, another COVID variant”. While an exaggeration, given the role of evolution in viruses, this new subvariant definitely won’t be the last. But how do we tackle this problem in the future?
- Going forwards, Abu-Raddad thinks researchers should move away from designing vaccines against single variants and instead focus on pan-coronavirus vaccines. “This would be a more fundamental solution for the future,” he says.
References:
Chemaitelly, H. et al. Preprint at medRxiv https://www.medrxiv.org/content/10.1101/2022.03.13.22272308v1 (2022).
