The new COVID variant, Omicron, is causing COVID cases to skyrocket, including in our community. Below is a summary of key things to know based on what we know so far. A more detailed report follows the summary.
Omicron is much more transmissible: 2x as much as the Delta variant, 4x as much as the original COVID. But cases rise exponentially, so each doubling of the transmission rate results in much more than a doubling of cases.
Omicron seems to be more mild, though we’re still figuring out how much is due to Omicron and how much is due to protection from boosters and more people with prior COVID infection. Even if more mild, with so many more cases it will stress the health care system.
Vaccination helps. Recent booster provides about 75% protection against getting infected, but probably over 90% reduction in hospitalizations and deaths. Two shots from a while back has much less protection against infection, but still reduces severe cases by about two-thirds.
Prior COVID infection and no vaccination – there are lots of reinfections, but they tend not to be severe cases. Less clear about people who had COVID as long ago as the first wave, March-May 2020.
Vaccination reduces spread by reducing the number of cases and for those getting infected anyway, by being infectious for a shorter amount of time.
Antibody treatments for previous COVID variants was very effective, but it seems that only one of the three treatments (sotrovimab – made by GlaxoSmithKline) works against Omicron and is in short supply already. This will be problematic for high-risk patients.
New Pfizer pill (Paxlovid) was just approved and will work great against Omicron – but it will be a while before there is much supply. It won’t help much with this wave. The Merck pill (Molnupiravir) was also just approved – not as good as Pfizer’s and with more side-effects, but will help while supplies of Pfizer are limited.
Even if we will all eventually get COVID, there’s value in boosters and mitigation methods, as excellent treatments are not far off. That’s aside from trying not to overwhelm the healthcare system, which can lead to worse outcomes for COVID and non-COVID patients and increase the incredible burnout rate in health care workers. And let’s not forget that there are people whose health prevents or limits benefit from the vaccine, so reducing spread protects them as well.
Vaccination and booster shots make a difference, both protecting yourself and others. People who are at higher risk for severe COVID should be more careful, e.g. consider wearing KN95 masks as opposed to surgical masks. It should be noted that some people don’t realize they are at higher risk, e.g. Age 55+ and very overweight. Also, with COVID rates high and rising in our community, people with even mild symptoms should be quick to suspect COVID and get tested.
After Delta cases had already been climbing sharply again, the new Omicron variant has been taking over. It seems to be the most common strain among new cases. Like everything new in COVID, it has gotten a lot of news attention, and early information is usually based on little data that is usually heavily biased. For example, the earliest reports, based on a small number of cases in young, healthy adults, claimed it is just sniffles and nothing to worry about. And the earliest cases had many vaccinated people (which got a lot of attention) as well as many people who had previously been infected with COVID (which got little attention). At this point, there are some things we have learned.
How Transmissible is Omicron?
Very! Delta is about twice as transmissible as the original wild-type virus that originally spread through the country. Omicron doubles it again. That puts it quite high on the list of most infectious diseases. For example, if a person infects 4 people instead of 2, and then those 4 each infect 4 others instead of 2 others, that’s 16 new infections from the 1st person, instead of 4. It grows exponentially. So twice the transmission rate means the cases pile up quickly.
Is Omicron More Mild?
Probably. Recent, large data from South Africa suggest it may have 29% fewer hospitalizations (though more in children) and those that are hospitalized are, overall, less severe than with Delta. But it is not clear yet to what extent that is due to the virus being less virulent and how much is due to protection from vaccination or prior COVID infection. Vaccination rates are low in South Africa but the vast majority had COVID prior to Omicron. The newest reports out of the UK show hospitalizations to be fewer and less severe – but still unclear how much is because Omicron is milder and how much is due to protection from boosters and prior COVID infection.
How Well Does Vaccination Protect Against Omicron?
First, let’s understand that there are two types of protection. COVID antibodies protect against infection, but wane over time (after vaccination or COVID infection). Low levels of antibodies worked well against the original wild-type strain, but not as well against Delta – and work far less well against Omicron. Protection against severe disease comes more from memory T-cells which recognize the virus or spike protein from the virus from previous experience – infection or vaccination. Memory T-cells wane slower than antibodies, so their benefit lasts longer following vaccination or prior COVID infection. Memory T-cells acquired through vaccination or prior COVID infection seem to fight Omicron infections as well as they fought prior variants.
Based on South African data and lab studies (which correlate well), recent booster should reduce infections by 70%-80% and severe cases by more than 90%. People with 2 doses and history of COVID infection are likely to be up in this range as well. 2nd dose of vaccine some months ago (and no booster) might reduce infections by 30% and severe cases by 70%. Protection against infection from prior COVID (and no vaccination) is not clear – South African data and UK data differ substantially for COVID in the last 6 months. People who have not been vaccinated but had COVID infection 12-18 months ago may have little protection against infection, but likely still fair protection against severe cases – but data is lacking here.
Does Vaccination (and Boosters) Reduce Spread?
Yes! When it was reported that people with breakthrough infections (infection after fully vaccinated) can spread the disease and have similar peak virus levels, this was often misinterpreted to mean they spread it as much as unvaccinated people who get COVID. Vaccination reduces spread in two ways: even with more breakthrough infections, fewer people with the vaccine get infected than without the vaccine (personal benefit, and communal benefit from no transmission); those that do get infected are infectious for shorter periods of time (communal benefit). So, yes, vaccinations reduce spread!
Do Antibody Treatments Work Against Omicron?
Several available monoclonal antibody treatments greatly reduced hospitalizations in high risk patients with Delta. It now looks like only one of the three (sotrovimab – made by GlaxoSmithKline) work against Omicron and it is already in short supply and will be for a while. The Pfizer pill (Paxlovid) is amazing! In high-risk patients with COVID-19, treatment reduces hospitalizations by almost 90%. It works in a totally different way than antibody treatments and should hold up as well against Omicron and hopefully against new variants to come. It just got approved for emergency use, but there’s a long manufacturing time and supplies will be very limited for quite some time. The Merck pill (Molnupiravir) was also just approved, and while it isn’t as effective at preventing hospitalization, the trials showed no deaths in those who got the Merck pill vs. 12 deaths in those who received placebo. There are more side-effects with the Merck pill.
Mendel Singer, PhD MPH
Associate Professor and Vice Chair for Education
Dept. of Population and Quantitative Health Sciences
School of Medicine
Case Western Reserve University