It seems that the so-called “stealth variant” is not so insidious anymore. It is now clear that the BA.2 Omicron subvariant of Covid-19 coronavirus has spread and spread and spread. Samples suggest that BA.2 may currently account for nearly a quarter of all new Covid-19 cases in the United States, up from about one-tenth the week before. The question then is whether this specific sub-variant will fuel yet another Covid-19 increase in general?
As the Centers for Disease Control and Prevention (CDC) Covid Data Tracker showsJanuary 2022 is when the BA.2 subvariant first appeared in samples from patients in the United States who had been sequenced. BA.2 originally got its “stealth” nickname, not because it wears a trench coat and sunglasses. Unlike the BA.1 and BA.1.1.529 Omicron subvariants, BA.2 can be difficult to distinguish from the Delta variant on polymerase chain reaction (PCR) testing. It was a possible erroneous identity problem back in January, when the Delta variant was still found in patient samples.
But by the time February came, things in the US had essentially become Omicron all along. The Delta variant had been displaced by the Omicron variants as a participant in the reality TV show Survivor. During the week ending February 5, BA.2 was present in only about one percent of all samples from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from patients around the country who had ended up with undergoing genomic sequencing. But in the ensuing weeks, that percentage has since moved up to 2.2%, 3.8%, 6.6% and 11.6%, respectively, until it reached 23.1% in the week ending March 5th. With BA.2 as an Omicron sub-variant in an Omicron world, it can be easier to distinguish on PCR. Therefore, the stealth nickname may no longer apply.
Why the BA.2 subvariant may cause another increase
The BA.2 sub-variant may soon overtake BA.1 for one major reason: it appears to be even more transmissible than the BA.1, which was already more transmissible than the Delta variant, which was already more transmissible than the Alpha variant. E.g, a study in Denmark described in a pre-print uploaded to medRxiv found that people were more than twice as likely to be infected when sharing a household with a person infected with the BA.2 subvariant, compared to a person infected with the BA.1 variant. And remember what happened in 2021 when the Delta variant “more-transferable-than-Alpha” arrived on the scene and then again when the Omicron variant “more-transferable-than-Delta” arrived. Both ended up pushing into something that rhymes with glue blasts: new waves.
At the same time, it seems that a large part of the United States is behaving as if the pandemic was over and has left Covid-19 precautions as if they were sweater vests. Of course, the pandemic is not over yet with an average of over 1,200 Covid-19-related deaths per day in the United States over the past two weeks. Remember what happened in the summer of 2021 after the requirements for face mask were relaxed which I covered for Forbes back then? And what about in the late fall, after many types of mass gatherings and travels were resumed, which I covered for Forbes as well? Both times there were subsequent Covid-19 increases, suggesting that both relaxations were premature. So the abolition of Covid-19 precautions such as face mask requirements over the past month may end up being another round of premature relaxation. It could leave the population as someone who wears nothing but a strap in the supermarket, a little too exposed.
Why the BA.2 subvariant may not cause another increase
However, things are a little different now than they were in 2021. A larger part of the population may have at least some degree of immune protection against Covid-19 coronavirus. More people have been vaccinated or infected with SARS-CoV-2 since the summer and fall of 2021. Given 65.3% of the United States, the population is fully vaccinated and 44.4% boosted against Covid-19 not amazing numbers. But this is a case where higher is better.
Data suggest that the efficacy of Covid-19 vaccination against the BA.2 subvariant is comparable to what it has been against BA.1. Eg. on March 10 It reported the British Health Security Agency that three doses of Covid-19 vaccines were approximately 69% effective against symptomatic Covid-19 caused by the BA.1 subvariant and approximately 74% effective against Covid-19 caused by BA.2 at the 2-week mark after the last booster dose. These figures dropped to 49% (48 to 50%) and 46% (37 to 53%), respectively, when the booster dose was given over 10 weeks ago, which is another reason why maintaining additional Covid-19 precautions would help .
The season can be another factor. March is not the same as November, when the weather got colder and drier. In March, conditions can be a bit temperamental like The Incredible Hulk, which ranges from cold to hot. So it is not clear how much they can favor the transmission of the virus.
The BA.2 subvariant does not appear to cause more severe Covid-19 than the BA.1 subvariant
Another concern is whether the BA.2 subvariant can cause more severe Covid-19 than the BA.1 subvariant. Although the recent winter rise, further driven by the Omicron variant, affected more people than the increase in the summer of 2021, a saving grace was that the Omicron variant on average seemed to cause milder disease than the Delta variant. A study described in a pre-print uploaded to bioRxiv raised some fur when it found out that the BA.2 subvariant can cause more serious disease than BA.1 in hamsters. This can be bad news if you happen to look in the mirror and realize that you are a hamster. Of course, finding out you’re a hamster can be bad news in itself if all your clothes are for humans and your workplace requires clothing.
Of course, as any nightclub owner will tell you, humans are not the same as hamsters. What happens to hamsters does not necessarily happen to humans. Also, take any pre-print with a bucket hat full of salt. This is not the same as a peer-reviewed study published in a reputable scientific journal. So far, human data have not found appreciable differences in the results of those infected with the BA.2 versus BA.1 subvariants.
There have been some warning signs of a possible impending rise
So it is quite clear yet whether BA.2 will fuel another Covid-19 increase. However, warning signs have already appeared. Which I covered for Forbes on Saturday, several countries in Europe have experienced the recovery of Covid-19 over the past week. In addition, wastewater surveys in the United States have found recent increases in the presence of SARS-CoV-2 as Julia Raifman, ScD, MScAssistant Professor of Health Law, Politics and Management at Boston University School of Public Health, recently tweeted:
So is this proof that the horse has already left the stable, the hedgehog has already left the nightclub, and the fart has already left his pants, so to speak, when it comes to yet another Covid-19 wave? Now, stay tuned.