JustThatVille
Given the ramped-up shipments of mRNA vaccines (i.e. Pfizer/BNT, Moderna) coming to British Columbia and the increased concern about significant, but still rare, clotting events after adenoviral vaccination (i.e. AstraZeneca, Johnson & Johnson), you may have pricked up your ears when you heard or read the following earlier this week:
British Columbians who received the AstraZeneca-Oxford COVID-19 vaccine as their first dose will likely be able to choose whether they want their second vial filled with the same vaccine, the province's top doctor has said.
Provincial Health Officer Dr. Bonnie Henry says as shipments of the Pfizer-BioNTech and Moderna vaccines increase, switching up the type of shot for the second dose is a possibility, as long as it is proven to be safe and effective.
"I expect people will have a choice," she told Stephen Quinn, host of CBC's The Early Edition, on Tuesday morning.
Henry said she is closely watching research being done now in the United Kingdom, where about 60 per cent of people were given AstraZeneca for their first shot. Researchers at Oxford University launched a study in early February to explore the possible benefits of alternating different COVID-19 vaccines...
It turns out that the group at Oxford (and Nottingham) that Dr. Henry referenced has now released preliminary data on the mixed vaccine regime, which they fancy up with the term 'Heterologous Prime-Boost'. This has led to a number of headlines like this...
So.
Mixing COVID-19 vaccine doses leads to more reactions, study finds, which may be 'first sign of success'.
So.
With that in mind, what does this group have to say, based on a letter they published in the Lancet Wednesday?
First, all they have released so far are data which looks at how folks who received either the AZ 'ChAd' adenoviral or the Pfizer 'BNT' mRNA vaccines first (i.e. the 'prime') and then received either the AZ or the Pfizer later (i.e. the 'boost') self-reported their symptoms.
First, all they have released so far are data which looks at how folks who received either the AZ 'ChAd' adenoviral or the Pfizer 'BNT' mRNA vaccines first (i.e. the 'prime') and then received either the AZ or the Pfizer later (i.e. the 'boost') self-reported their symptoms.
Second, they have only released data from folks who they received their 2nd 'boost' shot 28 days after their first dose. Here are the data of what those folks self-reported over the next 7 days:
As you can see, there are, indeed, increases in in reports for a number of indications (see 'Feverish' for example) after the mixing of the prime and boost (i.e. the second and fourth bar on each graph). However, most of this was self-reported as mild to moderate and there were no hospitalizations. The other thing, not noted in news reports, is that, generally, whenever anyone got the Pfizer/BNT vaccine, either once or twice (i.e. bars two through four on each graph), there were generally more events/symptoms reported.
As you can see, there are, indeed, increases in in reports for a number of indications (see 'Feverish' for example) after the mixing of the prime and boost (i.e. the second and fourth bar on each graph). However, most of this was self-reported as mild to moderate and there were no hospitalizations. The other thing, not noted in news reports, is that, generally, whenever anyone got the Pfizer/BNT vaccine, either once or twice (i.e. bars two through four on each graph), there were generally more events/symptoms reported.
Regardless, the kicker, according to the authors of the Lancet letter, is the following:
"(I)t is reassuring that all reactogenicity symptoms were short lived, and there were no concerns from the limited haematology and biochemistry data available..."
It is also important to note what was not (yet) reported in this letter - there was no report of these symptoms when the prime and boost were separated by 84 days (i.e. 12 weeks), as was done for most folks in the UK (and is closer to the Canadian/British Columbian paradigm, so far, of 16 weeks).
"(I)t is reassuring that all reactogenicity symptoms were short lived, and there were no concerns from the limited haematology and biochemistry data available..."
It is also important to note what was not (yet) reported in this letter - there was no report of these symptoms when the prime and boost were separated by 84 days (i.e. 12 weeks), as was done for most folks in the UK (and is closer to the Canadian/British Columbian paradigm, so far, of 16 weeks).
In addition, so far there have been no data reported on whether the vaccine mixture has positive effects on efficacy re: protection against infection and/or illness from the SARS-CoV-2 virus itself.
All of those data are supposed to be coming June which will be good timing around here as second dose times begin to roll in.
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