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Viral Weather: Herd immunity, creating a vaccine, and catching COVID twice?

Thursday, July 23rd 2020, 6:58 pm - From our Viral Weather program: Chris St. Clair speaks to an expert about developing a COVID-19 vaccine and why some people appear to be getting infected with the virus more than once.

While COVID-19 may feel like it's been in the news for a long time, in the world of viruses, it's still new.

There's still a lot we don't know, and it will be some time before we have a firm grasp on how the virus infects people and what its long-term effects may be.

One thing experts do know is that COVID-19 will be with us for a while.

Dr. Mark Cameron, an immunologist at Case Western Reserve University, says future coronavirus outbreaks are likely.

"We have to be ready and expect these viruses to emerge, and we have to lock them down and understand them more quickly because we do not other COVID-19 to occur and get past us like this one did," he says.

"Diligence, research, and international cooperation in identifying new infections and emergences is so important."


That's hard to say.

According to Dr. Cameron, experts were able to quickly develop a vaccine during the 2009 swine flu pandemic because it is easier to develop treatments for influenza.

"On the other hand, for coronavirus, there really hasn't [ever] been an effective vaccine," Dr. Cameron says.

"However, with COVID-19 this has given us the impetuous to figure it out."

vaccine - GettyImages-1205534989 File photo: Getty Images.


Over the past few months, we've seen disturbing headlines emerge of people recovering from COVID-19, only to test positive again days or weeks later.

Dr. Cameron says in some cases this can be attributed to false-positive tests. In other rare instances, it may be related to a poor antibody response.

"Usually, if you get a virus your body mounts an immune response to it and you have a memory of that virus and you have antibodies to deal with it," he says.

"You typically cannot get infected again with the exact same agent. However, with COVID-19, it looks like the antibody response our body produces, even if you get over the virus, isn't effective long term."

A low antibody response means the immune system may "forget" about the virus, leaving a patient susceptible to re-infection.

"As we develop a vaccine, that's something we have to keep in mind," Dr. Cameron says.

"It might be something we have to take every 5-10 years like a tetanus shot, to keep our immunity up."


Herd immunity occurs when most of the population is immune to an infectious disease. According to John Hopkins Bloomberg School of Public Health, it typically occurs when 70-90 per cent of a population is immune.

Vaccines can help with building herd immunity, but it's still not clear when a COVID-19 vaccine will be made available. Dr. Cameron says it could happen by early 2021 -- but realistically, it may be mid-to-late 2021 before an effective vaccine is on the market.

In the meantime, Dr. Cameron says it's important to continue practicing mitigation efforts, including mask-wearing, frequent hand-washing, and social distancing.

Watch the full 'Viral Weather' episode below:

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