COVID-19 vaccine campaign continues as Manitoba loosens restrictions

The medical lead of Manitoba’s Vaccine Implementation Task Force said Wednesday that the campaign will continue, despite the province aiming to lift all public health restrictions by mid-March.

“The work continues because we still need to reach those Manitobans who have not made the decision to be vaccinated,” said Dr. Joss Reimer during the weekly COVID-19 and vaccination update from public health.

Reimer then highlighted three recent studies that she said apply to people infected with Omicron, the most recent variant of COVID-19 that became dominant in the province and pushed the healthcare system to new limits.

The first study was done in mice that were infected with either the original COVID-19 strain, Delta or Omicron. She said scientists then used the blood from these mice to see if it could neutralize five different variants, including Omicron. What was found, Reimer explained, is the blood from mice infected with Omicron had a weaker immune response to neutralize Omicron, and no protection against any of the other variants. The blood from mice infected with Delta did better, but still did not neutralize all variants.

Reimer said the worry is people only infected with Omicron may not be protected going forward, but not much weight should be given to studies just done in mice because they don’t confirm the same happens in humans. She went on to say she brought this study up because there was a second part that did analyze blood from humans. This second half showed blood from someone infected with Delta could neutralize two of five variants, and if the person was vaccinated that jumped to five out of five. Reimer said the conclusion to this study was Omicron infections in people who are unvaccinated may not produce an antibody response that protects against other variants and in people who are vaccinated, the addition of an Omicron infection may be effective at producing antibodies.

The second study she cited was out of Austria. Reimer said researchers here looked at three different groups of people: those infected with Omicron only, those infected with Omicron following a previous infection, and those infected with Omicron who were vaccinated. She said it was found that vaccinated people or those who had a previous infection had high antibodies against all variants. In people who were only infected with Omicron, people had low antibodies against Omicron and tested negative for antibodies against all other variants. She said researchers here concluded unvaccinated people infected with Omicron only may not be protected well against any other non-Omicron variant and should subsequently be vaccinated to ensure they have protection.

The third study was out of South Africa, where Omicron was first documented. Reimer said scientists found unvaccinated people with an Omicron infection did not produce an immune response against any other COVID-19 variant.

WHAT DOES ALL OF THIS TELL US?

“If you’ve had two COVID infections or a vaccine and a breakthrough infection, your body does make a lot of antibodies against all the variants that we’ve seen so far. But if you’re unvaccinated and you were infected with Omicron, you might be protected against Omicron in the future but you won’t be protected against other variants,” said Reimer.

She added that for vaccinated or people infected twice, they don’t know how long these antibodies will last and they don’t know how well they’ll work in the real world against the existing variants or any future variant.

“This is why we still recommend that you get your next dose to give yourself the best possible chance to fight the next variant that comes even if you did have an infection,” she said.

She also said if someone never develops antibodies in the first place, they are still at risk.

“This is unfortunate. We had hoped that an Omicron infection, because there were so many of them, would help prevent further infection in people going forward. And what we’re seeing instead is in people who have never had any vaccine or previous infection before Omicron, it’s still critical for them to get vaccinated.”

Reimer said that’s why it’s important for people eligible to get their third dose, especially people 50 or older or someone with a pre-existing condition, and for children who are of eligible age to get vaccinated. She also said if you’ve recently had an Omicron infection to get vaccinated after a few months have passed.