LETTER: Omicron getting better at evading COVID vaccine

We have all been hoping to have a carefree and COVID free summer this year. Looking at the rapidly rising levels in wastewater, it seems, COVID may have other ideas.

While last year, in the time before Omicron, there were several factors which helped keep COVID numbers down, this summer, hospital admissions are starting to rise.

Here’s what you need to know to lower your risk, so you don’t spend you summer holidays alone and miserable.

Omicron continues to evolve, and the new variants keep getting more contagious.

In Ontario, BA.5 is now causing most of our infections and it is about 20 per cent more transmissible that previous variants. So it’s even easier get infected, especially from casual contacts. If you are outside, social distanced and there’s a good breeze blowing away from you, you are probably safe without a mask, being unmasked in any other situation is risky. The time since your last vaccination and your total number of shots affect your risks.

Omicron is getting better at evading vaccine induced antibodies, but it still can’t escape entirely. Recent vaccination can prevent Omicron infection, although antibody levels fall off within 2- 4 months. Severe disease is still prevented longer term, by other vaccine induced defences, but you really need at least three shots for best protection. So, if you still need a 3rd or 4 th shot, getting it now, and toping up your immunity, might help save your holidays.

If you get COVID, Paxlovid should keep you out of hospital, but probably won’t make you feel better sooner. For those at high risk for severe disease, taking Paxlovid within the first 5 days of developing symptoms and testing positive for COVID significantly reduces your chance of being hospitalized. However, it doesn’t decrease symptoms or shorten illness in low-risk individuals. Since Paxlovid interacts with a lot of medications, keep your medication list up to date and bring it with you to your appointment and when traveling.

Previous infections are no protection. BA.5 also evades antibodies from all previous infections – so even if you have had COVID before, you can easily get it again. Some unlucky people are now on their three round.

People are getting a second Omicron infection within 6-8 weeks of the first. Even those with 2 shots + a previous Omicron infection would benefit from a booster.

Repeated COVID infections are not always milder and may increase your risk for complications and long-term problems. A large, pre-print US study found that the more times you get COVID, the greater your risk to develop complications or persisting symptoms. Being unvaccinated had the highest risk but having at least 3 shots significantly reduced your risk.

Updated vaccines are coming – and so is Christmas. There are multiple new and hopefully better vaccines are currently in development, but it is unclear exactly when these will be readily available. Getting a booster now, should not prevent you from getting the updated vaccine when it becomes available later.

Choosing your activities wisely, wearing a mask whenever you are in a crowd or indoors and topping up your vaccines if needed can all help you have a COVID-free summer. And please, help protect our health care system by always wearing a mask, whenever you are in any health care environment.

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