The National Advisory Committee on Immunization updated its guidance Thursday to say that mRNA COVID-19 vaccines, such as Pfizer and Moderna, are the preferred second doses for those who received the Oxford-AstraZeneca vaccine as their first dose.
This has left many of the 280,000 British Columbians who have received the AstraZeneca vaccine curious, and in some cases frustrated, about what will happen next.
Here are some answers to questions about the AstraZeneca vaccine.
If I received AstraZeneca as my first dose, should I get AstraZeneca as my second?
British Columbia is not adopting NACI’s guidance and said British Columbians can still make a personal choice for either a mixed schedule or two doses of AstraZeneca.
“The very real world evidence shows us we have good protection across the board with both vaccines in our community,” B.C. provincial health officer Dr. Bonnie Henry said
Henry says B.C. is informing people to make the choice right for them, adding that all vaccines in B.C. are “safe and highly effective, and so are all of the options.”
“We still know from the information that we are seeing here in B.C., but also primarily in the U.K., where a lot of AstraZeneca has been used, that vaccine effectiveness is very good for both AstraZeneca and the mRNA vaccines,” Henry said.
Why did NACI change its advice?
The science around COVID-19 vaccines has been evolving and changing as more studies are done. This latest guidance shift is based on preliminary data from a German study that showed people who had an mRNA vaccine after a dose of AstraZeneca had immune markers as good or better than those who received two doses of AstraZeneca.
But Henry was quick to note it was a very small study that adds to the information that we know.
What benefits could an mRNA vaccine provide as a second dose?
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Health officials say both vaccination approaches are highly effective but mixing an mRNA after a dose of AstraZeneca may give some boost to the immune system.
What is still unknown is whether that translates into better protection.
What B.C. and the rest of the world still do not know is whether the little bit of extra antibody or the cell-mediated response translates into better protection in the real world.
How much AstraZeneca do we have in B.C.?
According to the BC CDC dashboard, a total of 339,839 doses of AstraZeneca have been administered in the province. That is out of the 438,000 AstraZeneca vaccines that have been delivered to B.C
There are 34,000 more doses on the way. The province has said anyone who received AstraZeneca as a first dose will have the option to get it as a second dose. So far about half of those who got AstraZeneca as a first dose have received it as a second dose while the other half have opted for the mRNA vaccine.
If I received two doses of AstraZeneca already, can I get a mRNA as a third dose right now?
B.C. does not see any evidence that getting an mRNA vaccine a short time after receiving two doses of AstraZeneca will be needed or that it provides any additional benefit.
In the U.K., the vaccine effectiveness after two doses of AstraZeneca was exactly the same as after two doses of mRNA vaccines.
Henry and health officials around the world are looking at whether boosters will be needed in the fall.
“It may be months from now that we’ll find that immunity decreases with one or the other combinations of vaccines, and it may decrease with all of them,” Henry said.
“There are studies going on both in the U.K. and here in Canada, in the U.S., looking at intervals as well. It may be that people who got the vaccine at a shorter interval may need a booster dose sooner.”
When the border opens, will I be able to travel to the United States where the vaccine is not approved for use?
B.C. expects that vaccines approved by the World Health Organization will be the standard that someone will need to meet.
AstraZeneca is approved by the WHO.
The expectation is mixing-and-matching will also be approved for international travel but that has not been determined.
“These are details that are still in flux,” Henry said.
“We don’t know the answers to everything yet, but we have heard, at least my colleagues in the U.S., that AstraZeneca will be one of the vaccine combinations that they will approve.”
If you travel to the United States and have been doubled-dosed with AstraZeneca will you be able to do the same things as those vaccinated with a vaccine approved in the U.S.?
So far Saturday Night Live, The Late Show with Stephen Colbert and Springsteen on Broadway have announced fans will not be allowed in if they are immunized with AstraZeneca. Guests must be fully immunized with a vaccine approved in the United States.
But the expectation from B.C. health officials is this will change as COVID-19 case numbers decline and international travel is encouraged. Ultimately, businesses will have the ability to choose how they set vaccination policies for admittance.
“I understand it was the concert venue itself that made those decisions for reasons that I don’t know,” Henry said.
“We do expect that it will be the standard that WHO sets that allows us to have a measurable standard around the world, and all of the vaccines that are approved for use here in Canada and all the combinations are approved by WHO as well.”
If you received AstraZeneca as a first dose, how long should you wait to get an mRNA vaccine as a second dose?
There is still no solid information as to what interval is best.
Henry said on Thursday that there is no evidence to say that a gap of eight weeks is better than 10 weeks, or 10 weeks is better than 12 weeks, or 12 weeks is better than eight weeks.
B.C. wants to reassure people that are up to 16 weeks between doses, there is data showing that’s just as good too.
The body doesn’t lose its immunity in that short period of time.
“I wish it were black and white, but what we can say is that we don’t actually know what the optimal interval is yet, but there is mounting evidence and I think most of us would agree that the short interval of three to four weeks that was used in the clinical trials is probably not the optimal interval,” Henry said.
“And we don’t yet know for other series of vaccines against viruses like hepatitis and others. It actually is better, longer-lasting if you get it about six months, but we have not yet had these vaccines for that period of time to be able to know how long immunity lasts.”
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