The next surge? It won’t happen right now despite the debate about the BA.2 “sub-variant”.

There has been quite a bit of discussion in the press about the most recent SARS-CoV-2 virus. U.S. public health officials are (for once!) being circumspect in their comments about the risk and have not called for reinforcement in public health restrictions. Importantly, there have been no increases in the number of cases or hospitalizations in the U.S.

Daily new COVID-19 cases. From the NYTimes

Despite the remarkable drop in US cases, several news organizations are raising concerns about whether there will be a surge in COVID-19 cases in the United States. Much of this concern comes from the fact that a surge in cases has been observed in some European countries attributed to what they are calling the “omicron BA.2 sub-variant.”

Note the recent uptake in new cases in the EU. The recent rise in infections does appear to have peaked this last week.

To understand the risk, it is important to first understand what is meant by an “omicron sub-variant.” The omicron virus called BA.1 that swept through the U.S. has a number of genetic alterations compared to the original COVID-19 virus. Omicron has over 30 mutations in the spike protein that binds the virus to cells. These mutations increase the risk that the virus is able to escape the protective antibodies from vaccination or a prior COVID-19 infection.

In contrast, BA.2 has only 8 unique mutations  and lacks 13 mutations vs. BA.1. BA.2 also shares around 30 mutations with BA.1. Since the two viruses are so similar, BA.2 is called a subvariant of Omicron vs. a new SARS-CoV-2 variant. Despite this, scientists have claimed that BA.2 is more easily spread and more resistant to therapy than Omicron.

Probably the two biggest determinators of whether there will be a US surge from this BA.2 sub-variant are when the virus arrives in the United States and whether it becomes involved in a significant proportion of U.S. cases. Recent studies have finally shed some light on this matter.

Evidence that BA.2 (yellow bars) has been present in US since December. It has been present in large numbers since early January.

The answer to when BA.2 arrived in the U.S. comes from a recent report on airport screening at international airports. The project initially screened travelers on flights from India to John F. Kennedy International Airport in New York, Newark Liberty International Airport in New Jersey, and San Francisco International Airport in California. In late November, screening was expanded to Hartsfield-Jackson Atlanta International Airport and involved travelers arriving from South Africa, Nigeria, Britain, France, Germany, and Brazil.

Proportion of Variants of SARS-CoV-2 in the US. BA.2 (pink bars) has rapidly risen to 35% last week, and is likely even higher today.

What became clear from this study is that BA.2 has been present in the U.S. since mid-December.  Importantly, the most recent data from the CDC revealed BA.2 is already responsible for 35% of the cases in the US!

Given both these pieces of information,  if a “surge” of cases from BA.2 were to occur in the U.S. it would probably already have happened. 

Published by jbakerjrblog

Immunologist, former Army MD, former head of allergy and clinical immunology at University of Michigan, vaccine developer and opinionated guy.

2 thoughts on “The next surge? It won’t happen right now despite the debate about the BA.2 “sub-variant”.

  1. Thank you once again Dr. Baker for being one of the few “voices of reason”. I wonder what your feeling is on the 4th dose? I am now almost 7 months out from my 3rd dose of Pfizer. Should I get the 4th? Should I switch to Moderna?

    Have you heard anything more about the Test &Treat plan that Biden announced during the Stat of the Union. The way he explained it is you got to the local pharmacies if you think you have COVID, the Pharmacist will test you, and give you PAXLOVID free on the spot if you are COVID positive. Sounds like a game changer for someone like me. I don’t want anything to do with the virus even a “mild” breakthrough infection. Do you know if there are any phamacies doing this yet in MI ?

    Thank you for your help!

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: