Thoughts on Omicron and Isolation

I haven’t written much about the Omicron variant of COVID-19, because the news (like the virus) is moving very fast, and I may not be the best person to sort through it all for you. And even the people who are most qualified to do that are doing what they should do - waiting for data before giving specific advice and changing guidelines.

But still, if you have been watching the pandemic news over the past two weeks (or if you live in New York City), you will realize that this variant is much more contagious than previous versions. Just about everyone that I know here knows multiple people - vaccinated and boosted - who have had breakthrough cases. So here are a few things that you might want to consider. And like most COVID stuff, these may all turn out to be wrong in a few weeks, so keep watching the data!

1) Even though Omicron is better at establishing infection in vaccinated people, the vaccines continue to do what they are supposed to do - prevent serious illness and death. Absolute case numbers are through the roof here in NYC (partially because we do so much testing), but we haven’t returned to the overflowing morgues and tent hospitals in Central Park that we had in the spring of 2020. Our immunity wall seems to be holding up - 84% of the Manhattan population over age 5 is fully vaccinated. Breakthrough cases aren't a failure of the vaccines, their generally mild nature show how lucky we are to have had our shots.

My vaxxed and boosted son flew in from the west coast to spend the holidays with us. I was really looking forward to hanging out with him, but he got a breakthrough case and had to isolate, so we visited on zoom. Because he was protected, I was disappointed but not terrified, which is a big deal.

2) Compared to Delta, Omicron MAY be less lethal for any given person. There is some evidence that lung injury (the major cause of death from COVID) is less common. However, people are still dying of it. Do NOT let down your guard in terms of mitigation strategies during this surge in cases. Remember that it's not only about you and your personal comfort level. More cases always leads to more deaths - among the unvaccinated and those with serious underlying health issues. Mask up in public indoors. Keep the ventilation as good as you can get it. Don’t eat inside in restaurants. Consider having people test before indoor social events. This won't last forever, but we are in a tough spot right now.

3) Even if your vaccine will save your life, and even if acute Omicron infections turn out to be less lethal than Delta, it’s STILL better to avoid COVID-19. More infections means more community transmission. That means more chances for the virus to evolve further, into future variants. It also means more economic and psychological costs of the isolation period (more on that below). And, of course, we are only two years into the pandemic, so there is a lot that is still unknown about long COVID in recovered individuals and the future implications of past infection.

4) If you are six months out from your Pfizer/Moderna second shot, and you aren’t boosted, you aren’t well protected. I don’t consider you fully vaccinated, even though the app on your phone does. Looking at the most recent CDC data for deaths per 100K cases, it’s 0.5 for vaccinated and 0.1 for boosted. For unvaccinated, it’s 6.1. That’s over sixty times the chance of dying compared to boosted individuals. And with a more contagious variant, that means a LOT more cases, which means more deaths.

5) Past infection without vaccination (“natural immunity”) seemed to provide some protection against Delta, although not as good as the vaccines. It does NOT seem to provide much protection against Omicron.

6) Up until a few hours ago, the CDC isolation recommendation after COVID infection was 10 days after symptom onset (or positive test for those who never develop symptoms). But people MUCH smarter than me had pointed out that the 10 day requirement was determined in the early days of the pandemic, before we knew as much about the contagion window, and before vaccines.

Since we can now determine that some people become less contagious sooner than 10 days, letting them out of isolation (even with more stringent masking requirements) is a big advantage. Long isolation is a huge problem for so many people. For caregivers of young children. For people paid hourly, with no sick days. And for people doing critical jobs that aren’t easily replaced.

The New York Department of Health did this on December 24th, modifying isolation requirements for health care personnel and some other essential workers (who commonly have minimally symptomatic breakthrough infections). After five days of isolation, they were allowed to return to work with a high grade mask (e.g. N95, KN95 or KF94) if they have improving symptoms, no fever for 72 hours without meds, and no cough or runny nose.

Today (December 27th), the CDC extended that modified guidance to everyone, essentially mirroring the NY DOH guidelines with some minor differences. This is understandable, and there was no reason to limit this to medical personnel - this was an issue in many industries. Having healthy people who are not very contagious sit at home for day 5-10 after infection is a huge psychological, financial and operational burden on so many systems. For example, airlines had to cancel a lot of flights over the holidays due to staff being out on isolation.

As Omicron massively increased the number of healthy people falling under isolation requirements, this was becoming even more urgently needed. Of course, you want to contain the spread, but if people really aren’t contagious (or are minimally contagious, and that can be addressed with masking), letting them get back to work is a big benefit for them, their families, and society in general.

But you should know that this isn't just surrendering public health to economic reality - there really is good reasoning behind this decision. Dr. Ashish Jha (who you all should follow) suggested the following prior to the DOH and CDC announcements. Read his thread for the details - it’s one of the few things that makes it worth going on Twitter! The logic behind this is really solid and fascinating, I’ll summarize here because this is already too long…

Since we isolate to stop the spread of COVID, we should do that as long as someone is contagious, and their contagion window depends on a lot of variables. We have basically two ways of testing - molecular tests (e.g. PCR), that are expensive, slow, and essentially limited to medical facilities, and home antigen tests (e.g. BinaxNow, CareStat) that are quick, cheap and can be done by anyone at home. These antigen tests are referred to as "lateral flow" tests in the diagram below.

Antigen tests aren’t as sensitive as PCR, so they can miss infected people (false negative), especially soon after exposure. But that really means that they need a higher viral load to be positive. So if you want to make sure, for example, that you don't let anyone with a new, developing infection on an airplane who will soon be shedding virus, PCR is better.

But what we actually care about in this situation (determining the end of isolation AFTER infection) is contagion, not picking up every person with minimal or non-contagious viral shedding. People can have a positive PCR for weeks after infection, but we don’t make them isolate until that’s negative. If the antigen test converts from positive to negative in an isolated patient, that's a good sign of significantly reduced contagion potential.

Dr. Jha suggested 5 days of isolation followed by a home rapid antigen test for someone who is without symptoms. To be extra careful - for example, if they are in contact with high risk people - a second antigen test would make a false negative due to testing errors very unlikely. Limiting this strategy to vaccinated people would also provide an increased measure of conservatism, as it seems that the vaccinated may be contagious for a shorter time.

The CDC and DOH updated guidelines don't depend on testing, and only the DOH version requires vaccination. They both require high grade masking around others for the second 5 days. From my point of view, a negative home antigen test (or two) on day 5 would go a long way towards convincing me that someone was no longer contagious, as would having been boosted.

No one wants lockdowns, remote learning, or isolation. But this isn’t the spring of 2020. We have tools to fight this virus - vaccines, antiviral drugs, and knowledge.

Let’s use them. Let’s #stopthespread.