Danika writes:

Hello Dr. Griffin and TWiV team!

I am 30 weeks pregnant today and just got my COVID booster this morning after being cued into the research on the benefits of maternal vaccination on infant hospitalization, in particular in the 3rd trimester, from being a loyal TWiV listener. I now have had 4 moderna doses.

Anyway, word “got out” that I made this decision to get vaccinated and both my mother and mother-in-law contacted me in horror about my decision and are very worried about my unborn child.

While I certainly don’t agree with them, and, as an epidemiologist myself, I do not agree with their assessments of the literature, my mother sent me this article recently published in the journal, Vaccines.


I admit, this article went over my head quite a bit, but sounds a little bit like what I’ve been hearing about “antigenic sin” perhaps? I understand that a lot in this article is speculation, and clinically, we see plenty of good coming from vaccinations and at least 2 good papers on benefits of getting vaccinated during pregnancy that put me at ease.

However, I would really love a breakdown of this article. In particular claims like this, 

“Even the protection that COVID-19 vaccines provide against severe symptoms and hospitalization is now being questioned following an outbreak in an Israeli hospital that resulted in the deaths of five individuals (all with comorbidities) who were fully immunized”


“All in all, reviewed data indicate that IgG4 production induced by repeated vaccination does not in any way constitute a protective mechanism. There are also warning signs in recent literature that indicate the cellular immune response induced by the typical vaccination course may be severely compromised by repeated administration of the same booster shot or infection following vaccination, which, in combination with impaired antibody immune responses, may cause recipients’ symptoms to worsen or their disease to last longer. Excessive vaccination is likely to create an immunosuppressive microenvironment that is crucial for promoting immunological tolerance.”

Would love to hear your thoughts.



Caroline writes:

Dear Dr. Griffin, my 26 year old son is planning a rock climbing trip to Kliphius ( 3 hrs from Cape Town) South Africa.  Does he need any updated vaccines.  Thank you.

Caroline Wong, M.D. (nephrologist that follow Vincent on Q and A, and office hours)

Tom writes:

Dear Dr. Daniel,

Thank you for all that you and the entire TWiV team do to keep us informed. I am a 68 year old man, with no other known factors that put me at risk for severe Covid other than my age.  I have not yet had the virus. 

And thanks to your recommendation I have a plan.  I have been in touch with my doctor to be sure that if I do get infected, he will prescribe Paxlovid, and not suggest I “wait and see” or prescribe something that will do me no good.

My question relates to an upcoming trip I have to Europe (Ireland/Scotland), which introduces a hitch in my plan. I will be gone for about 2 1/2 weeks.  So if I were to be infected with SARS-CoV-2 in the early days of the trip, I would not be able to get a Paxlovid prescription from my doctor within the optimum treatment window.  

What suggestions would you have for someone like me to protect myself? I have had three boosters of the RNA vaccine, including the bivalent.  But the last was in December, so I would expect that my antibody levels have contracted. I plan to wear a mask while traveling. I’d like to be able to take Paxlovid with me just in case. But can a primary care doctor prescribe it “just in case”? 

What do you recommend?

Tom Andre

Pasadena, California

Marcus writes:

Hi, I’m a GP in Australia and we have run into a problem where the government is no longer supplying paediatric Moderna vaccines (6 month to 4y) due to contract issues.  They do have access to the Pfizer Paediatric vaccine.  For children that have already had 1 Moderna vaccine is there any evidence for mixing vaccines ie Moderna first Pfizer second despite the difference in dosing regimes?  Alternatively there is an option to bring forward the 2nd dose (8 weeks later) forward to 4 weeks, is that a better option?  Wanting to do the best by my patients.


Laurie writes:

Good morning.  I am a partner in a busy pediatric practice in SF.  The FDA has come up with confusing new recommendations mandating that we get rid of the ancestral vaccine (no!) and replace it with the bivalent.  As part of this new recommendation, we are supposed to start giving infants the 6-12 yo dose (or we can give Pfizer.)

Is there any science behind this?  What does the FDA advisory committee think about this?  Should we implement this before the ACIP weighs in?

We appreciate any insights you can provide.  Thank you once again.

Laurie Schultz MD MPH

Golden Gate Pediatrics