A couple of weeks ago I wrote about COVID-19 variant B.1.1.529, better known as Omicron. One of the notes I ended with was that more information was forthcoming in the next two to three weeks, and that is exactly what happened. Again we a owe a huge acknowledgement to the South African scientists who test and track variants for helping to get us started in identifying this variant and how to address it.
We are still learning a great deal about Omicron. So far, in some early studies that have been conducted, we’ve seen that the variant seems to replicate more and faster in upper airway tissues (meaning that it could potentially spread much faster since that’s where respiratory droplets emanate from). Conversely, it seems to replicate more slowly in lung tissues. Scientists are hopeful that this means that it will cause less severe disease (maybe in the setting of early treatment). However, these are ex vivo studies, meaning they are conducted outside the human body in controlled tissue environments, which does not always translate when applied to a real human. That part remains to be seen.
In South Africa, there does seem to be a lower hospitalization/ICU rate compared to case/infection rate and compared to previous variants, but it’s not clear if this is truly representative or more a reflection of South Africa’s smaller and overall younger population (average age 10 years younger) with some degree of background immunity (due to past infection - not very reliable - and vaccination - more reliable but not as widespread in that community). Even with that, one person in South Africa spread it to at least three people (twice as fast as Delta in South Africa - cited in an article below). It is also burning through the United Kingdom at similar rates. This may wreak worse havoc as it spreads through the United States. So no, we don’t know if this is “more contagious but milder” and we should not take the chance when we have so many vulnerable people here (the immunocompromised, kids <5, the elderly) and a much greater chance of breakthrough or reinfection overall. Omicron, by some estimates, is thought to already the dominant strain in parts of the northeast and other areas.
There is a thought going around that viruses consistently evolve to become less virulent despite increased contagion - this is not true and has never been proven (at least not universally). Moreover, even if Omicron does cause "milder" disease (which, again, is not proven), that does not mean we're off the hook. We have a lot of evidence to show that even mild, non-hospitalized cases of COVID can result in Post-Acute Sequelae of COVID-19 or PAS-C ("Long COVID"). Death is still not the sole consequence of COVID, nor should it be the sole focus in outcomes.
As we near the peak of this fifth wave, with Omicron already working its way through parts of the US, a cry has once again risen of "Just let it rip through" and "we'll all get it eventually", and of course, the chorus of "just let it infect so we can get to herd immunity." I quote myself (I know, how conceited): I refuse to believe it is "inevitable" that "everyone will get COVID." I know I have to accept that it's a possibility, but that translates to a lot of people (most of whom will be less privileged than me) dying because they won't get the same resources I could if I got infected. Vaccines plus mitigation strategies remain the sole way to get through this without devastating loss. As epidemiologist Dr. Ellie Murray stated recently, we should demand better.
Ed Yong, one of the consistently best science writers, wrote a piece for The Atlantic and I honestly encourage you to read it. He remains masterful at putting things into understandable terms. He notes that Omicron is "A setback but not a catastrophe for most vaccinated people."
"The Omicron wave won’t completely topple America’s wall of immunity but will seep into its many cracks and weaknesses. It will find the 39 percent of Americans who are still not fully vaccinated (including 28 percent of adults and 13 percent of over-65s). It will find other biologically vulnerable people, including elderly and immunocompromised individuals whose immune systems weren’t sufficiently girded by the vaccines. It will find the socially vulnerable people who face repeated exposures, either because their “essential” jobs leave them with no choice or because they live in epidemic-prone settings, such as prisons and nursing homes. Omicron is poised to speedily recap all the inequities that the U.S. has experienced in the pandemic thus far."
"Vaccines can’t be the only strategy, either. The rest of the pandemic playbook remains unchanged and necessary: paid sick leave and other policies that protect essential workers, better masks, improved ventilation, rapid tests, places where sick people can easily isolate, social distancing, a stronger public-health system, and ways of retaining the frayed health-care workforce. The U.S. has consistently dropped the ball on many of these, betting that vaccines alone could get us out of the pandemic."
It's a really good piece. I certainly learned from it.
Let’s talk about what everyone wants to know: is Omicron going to escape vaccines?
The data from Pfizer’s testing offers some good news and bad news. The bad news is, there does seem to be a reduced neutralization from the two-dose regimen. Against hospitalization, vaccine protection seems to be down to 70% (compared to 93% against Delta). Against any infection, the two-dose series‘ effectiveness seemed to drop to 33% (80% against Delta), which…sucks.
BUT there is a solution! The third dose brings it back. Pfizer and Moderna have both released data regarding their booster/third-dose effectiveness against Omicron (remember in my last post I discussed how the COVID-19 vaccine is looking more and more like a three-dose vaccine, not unlike a few others we already have). This is not a political control move or any other conspiracy you’ve heard, and it doesn’t mean these vaccines aren’t working. We are learning about this virus and its evolution with each passing week. Third doses of the mRNA vaccines (or an mRNA vaccine after the J&J vaccine) get your antibodies (number and range of immunity) back up to a level comparable to a two-dose regimen vs. Delta. So far it does not seem like infection-mediated immunity is holding up against Omicron (but hybrid immunity - vaccine+infection - does to an extent).
Moderna reported that its booster dose (50mcg) yielded a 37-fold increase in antibodies against Omicron, while its full third dose (100mcg) yielded an 83-fold increase. Pfizer also reported that its third-dose/booster (same amount as second dose) yielded nearly a 25-fold increase in antibodies.
Several people have asked me the reasoning behind the difference in dose and booster recommendations for kids age 5-11 and 12-18 (and now the recommendation for boosters in 16-18). The short answer is: the difference is not for body size, but for maturity of the immune system. While this varies from person to person, there is a general evolution in the immune system's maturity and ability and processes from age group to age group. The boosters are now recommended for 16-18 because that's the data we have, timing-wise - younger kid vaccines were approved more recently so we haven't fully evaluated the need for boosters yet.
So, in short - get vaccinated, and if you qualify, get boosted (>6 months since second mRNA dose or >2 months since J&J dose, and at least 16 years old), and maintain these other mitigation strategies! As always, #GetVaccinated to protect yourselves and your loved ones, and each other's loved ones. In fact, #GetVaccinatedAndMitigate this holiday season. Get tested the day you're going to see family and have backup plans. And as usual, I welcome your questions.
https://www.imperial.ac.uk/media/imperial-college/medicine/mrc-gida/2021-12-16-COVID19-report-49.pdf