LETTER: COVID’s Omicron variant less severe for the vaccinated, boosters decrease transmission

It’s been just over six weeks since the Omicron variant of COVID was detected in Ontario.

As the cases continue to skyrocket, we are learning more about how Omicron differs from previous variants. This recent data is extremely important as we adapt our response to this latest wave.

Omicron replicates and transmits much faster than any other variant and most people are infectious a few days before they feel sick. If you are vaccinated, you may not have any symptoms. Cough and runny nose are the most common symptoms, followed by fatigue, headache and fever. Pneumonia is less common, but it can cause croup in young children. Living with someone who has COVID gives you a 30-50 per cent chance of getting infected, higher if you are not vaccinated. Therefore, household contacts need to isolate for five days even if they have no symptoms. While the initial illness may be less severe, the risk of long COVID or other complications remains the same.

Omicron’s 34 mutations make it more challenging for antibodies from vaccinations or previous infections to recognize it. Even so, having two shots is associated with less severe disease. In Ontario, right now, you are 80 per cent less likely to be hospitalized from COVID if you have received two vaccine shots and 90 per cent less likely to be admitted to ICU. Delaying the second shot also seems to have given many of us better protection against getting Omicron, compared with countries that didn’t. The delay between shots gives your immune system time to learn from the first exposure and allows it to develop a stronger and more complex response. After the second exposure, that response broadens, helping the immune system to better recognize changes in the invading virus.

Getting a booster after three months decreases your chance of getting Omicron by up to 50 per cent. That third shot causes our immune systems to create an even greater variety of anti-COVID antibodies, including those much more likely to recognize and attack Omicron. Fortunately, most people also have fewer side effects from their booster and the risk of myocarditis is lower. Mixing vaccines may provide slightly better protection. The most recent data also suggests that Moderna works slightly better against Omicron than Pfizer. This is very good news, given that we currently have lots of Moderna and lots of vaccination appointments available.

For those who are double vaxxed, getting your booster ASAP will increase your protection and help decrease transmission. Getting more first shots into those who are eligible is also critical, particularly before the next wave comes. For those needing a second shot, particularly the kids, the immunity data suggest that waiting the eight weeks, if possible, will provide better coverage in the long term. However, personal risk for severe illness or complications, along with risk for exposure need to be considered. If you have concerns, it is best to discuss these with your primary health care provider.

Regardless of your vaccination status, keep your masks on, wear the best mask you can find, and keep your distance.

Kristin Morrison, M.D., F.R.C.P.C. (Pediatrics)