New Brunswick

Got questions about your first dose and the protection it offers? These experts have answers

Now that most eligible New Brunswickers have received their first dose of the COVID-19 vaccine, experts answer questions about how protected people can feel now, the variant threat, and more.

As N.B. closes in on 75% vaccinated goal, here are some insights into what that first shot means

About 73.6 per cent of the eligible New Brunswick population has received a first dose of COVID-19 vaccine. (Andrew Vaughan/The Canadian Press)

As of Friday, 73.6 per cent of eligible New Brunswickers had received at least their first dose of a COVID-19 vaccine.

Once that hits 75 per cent, the province will enter Phase 1 of its reopening plan and residents will have a host of new freedoms, including as the ability to travel freely to and from P.E.I. and Newfoundland and Labrador and the elimination of the steady-15 rule.

But as that 75 per cent mark nears, many have questions. 

Can you stop worrying about getting sick?

How safe are you against variants?

What about delaying second vaccine doses? 

CBC News spoke to experts on these topics and more. Here's what they had to say:

Can I relax after a single dose?

While it's still necessary to follow Public Health orders, someone who has received their first dose should feel an added level of comfort knowing they have more protection than they did before getting the shot, said Caroline Colijn, a mathematics professor at Simon Fraser University who has worked on models that forecast COVID-19 case counts under various circumstances.

"After two or three weeks, protection looks pretty good, and you should know that both you and the people around you are protected."

If both you and the people around you are vaccinated, the risk of transmission "really gets quite low," Colijn said.

"It's not to say it's zero – vaccines are great, but they're not 100 per cent – but I think if you're following public health guidelines, it's a huge additional level of protection to have those people vaccinated even with one dose, as long as it's been those few weeks."

Caroline Colijn, a mathematics professor at Simon Fraser University, said a first COVID-19 vaccine dose offers good protection against catching the disease or spreading it. (Courtesy of Caroline Colijn)

Does the vaccine decrease ability to spread COVID?

The short answer is yes. Getting vaccinated will reduce one's chance of spreading COVID-19, Colijn said.

That chance of spreading it is further reduced when interacting with others who have received at least their first dose.

"So, first, you're protected from getting infected in the first place. Then if you are infected, the virus load in your body is probably lower and you're less infectious," she said.

"Even with one dose, it is a very different situation than in an unvaccinated population where neither party has been vaccinated."

What about protection against variants?

Cases are declining in all provinces, but variants are still something of a wild card.

Colijn notes there is limited real-world clinical data on the effect of vaccines on variants, which means it's important for provinces to remain vigilant to reduce their spread.

Of the known variants of concern, she thinks the Delta variant,  which was originally detected in India, is the one that should be most on our radar right now.

"I do think we need to keep monitoring what's happening with the variants of and vaccinations," she said.

The U.S. Centers for Disease Control and Prevention says current data suggest COVID-19 vaccines offer protection against most variants currently spreading in the U.S., though some variants might cause illness in some people even after they have been fully vaccinated.

Is a delayed second dose still effective?

When they first released their vaccines, the makers of Pfizer-BioNTech and other vaccines advised people get their second dose within three weeks of receiving their first.

But supply concerns have pushed officials in many jurisdictions to delay administering the second dose by as much as 16 weeks for the sake of getting first doses into as many arms as possible.

While studies have found peak immunity comes from spreading the two doses out by 12 weeks, waiting a little longer would not be an issue, said Dr. Krishana Sankar, a science advisor for an online anti-misinformation initiative known as Science Upfirst.

Krishana Sankar is a science advisor for Science Upfirst, says the efficacy of a COVID-19 vaccine isn't affected if the second dose is delayed. (Submitted by Krishana Sankar)

However, Sankar cautioned, there are "a few things that we have to consider when getting our second dose," including efficacy, supply and variants.

"Because we do have variants of concern circulating, it would be more effective if we are able to get our second dose of the vaccine sooner rather than later," she said.

Is a second AstraZeneca dose safe?

The AstraZeneca vaccine raised concerns after reports linked it to rare occurrences of blood clots.

The vaccine has been linked to two deaths in recipients in New Brunswick, and last month, the province announced it was no longer offering it to people as their first dose, but would continue administering it to those who wanted to have it for their second dose.

While there still is a risk of getting blood clots on the second dose, the risk is much lower, with a chance of one in 600,000, Sankar said.

"So the risk is rare, but it is present," she said.

"It's important for people to be aware of that and know what the signs and symptoms are, and to immediately go to the ER if they do see those signs or symptoms."


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