I'm in the same position (were you also an eventually-unblinded placebo arm subject?) and after looking around at the literature, I've decided to not decide until day 57 post injection (the interim used in ENSEMBLE2). For now, let your immune system make use of what it has.
The answer scientifically is that I don't know, and nobody knows for certain. I don't see why it would be *harmful*. I can see a logistical argument that it would take a dose from someone else.
Let's look at the regulatory position on this. The EUA for the Pfizer vaccine, as an example, says the following: "There are no data available on the interchangeability of the Pfizer-BioNTech COVID-19 Vaccine with other COVID-19 vaccines to complete the vaccination series. Individuals who have received one dose of Pfizer-BioNTech COVID-19 Vaccine should receive a second dose of Pfizer-BioNTech COVID-19 Vaccine to complete the vaccination series."
This does not currently directly address your question. However, it suggests a spirit of avoiding the mix-and-match approach or using different vaccines in the same person. In the strictest sense I support this approach given the absence of data.
One thing I would mention is that, if you are concerned about the slightly lower reported efficacy of a single dose of the Johnson and Johnson vaccine compared with Pfizer or Moderna's vaccines, you shouldn't be. There are no head to head trials of these products and we cannot compare them directly. Even more importantly, there is an ongoing trial of two doses of the Johnson and Johnson vaccine. This trial is called ENSEMBLE 2. Once it reads out the Johnson and Johnson EUA is likely to be updated to include the results of this trial and I anticipate that a 2-dose regimen may be offered to people who received one dose. I would wait for this to happen, if I were you, especially given the labeling language I quoted. I think the data are just too murky right now to be sure of whether or not this is a good idea, and the vaccine you have already received is adequate to protect you from the most serious outcomes.
I got the J&J vaccine on March 7, and now my health care provider is offering me an mRNA vaccine. Would a double vaccination help? Hurt? Waste a dose?
I'm in the same position (were you also an eventually-unblinded placebo arm subject?) and after looking around at the literature, I've decided to not decide until day 57 post injection (the interim used in ENSEMBLE2). For now, let your immune system make use of what it has.
Good question.
The answer scientifically is that I don't know, and nobody knows for certain. I don't see why it would be *harmful*. I can see a logistical argument that it would take a dose from someone else.
Let's look at the regulatory position on this. The EUA for the Pfizer vaccine, as an example, says the following: "There are no data available on the interchangeability of the Pfizer-BioNTech COVID-19 Vaccine with other COVID-19 vaccines to complete the vaccination series. Individuals who have received one dose of Pfizer-BioNTech COVID-19 Vaccine should receive a second dose of Pfizer-BioNTech COVID-19 Vaccine to complete the vaccination series."
This does not currently directly address your question. However, it suggests a spirit of avoiding the mix-and-match approach or using different vaccines in the same person. In the strictest sense I support this approach given the absence of data.
One thing I would mention is that, if you are concerned about the slightly lower reported efficacy of a single dose of the Johnson and Johnson vaccine compared with Pfizer or Moderna's vaccines, you shouldn't be. There are no head to head trials of these products and we cannot compare them directly. Even more importantly, there is an ongoing trial of two doses of the Johnson and Johnson vaccine. This trial is called ENSEMBLE 2. Once it reads out the Johnson and Johnson EUA is likely to be updated to include the results of this trial and I anticipate that a 2-dose regimen may be offered to people who received one dose. I would wait for this to happen, if I were you, especially given the labeling language I quoted. I think the data are just too murky right now to be sure of whether or not this is a good idea, and the vaccine you have already received is adequate to protect you from the most serious outcomes.
it's not j&j but there is a current study of astrazeneca and pfizer in the uk, and some other discussion of mixed vaccines here: https://www.nature.com/articles/d41586-021-00315-5