Adrian writes:

If we decide to get the bivalent booster, how important is the timing?  My wife saw an article claiming that you shouldn’t get it sooner than 4 months after a previous COVID infection because the body won’t develop a strong immune response to the shot, but I recall guidance on TWIV that people could get the vaccine a few weeks after infection.   So does the timing matter?  (My daughter and I had COVID in July, only 3 months ago.)  It seems like ideally we would want to get the shot to maximize the period where we experience temporary immunity to infection, which would suggest at least 6 months between shots.  But does that mean six months since a COVID infection as well?   Would the answer be different for my kids, aged 17 and 20 than for my wife and I, who just entered our 50s? 

Anthony writes:

Hi Daniel, 

I just received my bivalent booster of the COVID-19 vaccine but am also prescribed hydroxyzine for anxiety and was wondering if you knew anything about anti-histamines reducing the efficacy of a vaccine because of reduced inflammation and thus reduced immune activation.

Thanks for all the information you and Vincent provide.



Bradley writes:

I love your podcasts!!! This is my question. I was told that I should wait at least 14 days after taking Covid-19 booster before taking a live vaccine. Could you explain this waiting period vs. vaccines that are given simultaneously? I had the opportunity to take my first Jynneos intradermal vaccination at a festival in San Francisco this last weekend, so I did even though I was only 10days post Covid-19 booster. It was convenient – no waiting in lines. Do I have anything to worry about? I am 63 and sure I had DryVax when young. I have quite an injection site reaction.

Erica writes:

Hello Dr Griffin,

I first want to start by saying thank you to you and Dr Racaniello for the incredible service you are doing for the scientific and general public community. I realize what a great time commitment doing all of these podcasts (TWIV and TWIP) is, so my students and I are incredibly grateful. I teach undergraduate Medical and Molecular Virology at Colorado State University (with Tony Schountz, who has been a guest on TWIV).  I share TWIV with my students often, and often have students bring to my attention interesting shows, so I know first hand what a great resource TWIV is.

I am curious if you have any clinical experience with patients who have Mast Cell Activation Syndrome and COVID.  I was originally diagnosed with Mastocytosis that they later downgraded to MCAS, and I am very well controlled with lots of H1 and H2 antihistamines and Elmiron, without having to take Cromolyn.  I have read that patients on the mast cell stabilizers are actually less likely to progress to hospitalization, and I know that famotidine has been correlated with better outcomes (I am on high doses of famotidine).  What I cannot find any information on is, do people with MCAS have to be more concerned about long-COVID?  There are publications indicating that many of the symptoms of Long-COVID are the same as those seen in MCAS, and speculation that SARS-CoV-2 may be causing/exacerbating MCAS. (Int J Inf. Dis. 2021 Nov 112:217-226 Mast cell activation symptoms are prevalent in Long-COVID Weinstock at el. Int J Infect Dis 2020 Nov: 100:327-332 COVID-19 hyperinflammation and post-DOVID-19 illness may be rooted in mast cell activation syndrome) but I can find no data about if people with MCAS are actually more likely to develop long-COVID.  Thank goodness so far I have not had COVID (I know I am N antigen negative by ELISA as I am donating blood to a colleague’s study looking for immunological markers that might predict a person’s likely hood of developing long-COVID.) My primary care says she wants me to be extra careful, which I have been (my husband and I, like you and your wife, appear to be the only people still wearing masks in Fort Collins 😊).  She says she has no idea how COVID would affect me.  So I am curious if you are seeing any MCAS patients, and if they are more likely to develop long-COVID?  I realize there are not very many of us with diagnosed MCAS, which may be why this data is not available, but would appreciate your insights if you have any. 

Thanks for all you do.


Erica Suchman PhD
University Distinguished Teaching Scholar
Department of Microbiology, Immunology and Pathology
Colorado State University

William writes:

I have heard some talk about using high dose influenza vaccine in immunocompromised patients under 65years old.  Is this a good idea?

William Hardman , M.D.

I appreciate the work you do to keep me up-to-date with your webinars.  You and Vincent are excellent teachers!

Carol writes:

Thank you so very much for your weekly updates. They have been invaluable to me and I’m sure a lot of other people. 

As you have recommended, I have tried to get a plan in place for the day that I test positive for COVID-19. I am 65 years old with no health conditions that would make me have a negative outcome from Covid. But I would still like to be prescribed paxlovid because of my age. My significant other is the same age as I am and otherwise healthy. Neither of us takes any medications. We have the same primary care physician. My significant other recently tested positive for Covid and was required to have a creatinine blood test done before he was prescribed paxlovid. I have never heard you give this recommendation and I have serious doubts as to the necessity of this hoop that we are being required to jump through, to say nothing about the expense ($230). I messaged my primary care physician and this is the response I got:

“You are correct, you need to have a creatinine done in the last six months, 

Your last one was in late 21, so I will put in the order and you can come in to the lab and get that done, 

We don’t give it out prior to any infection, and I would also say, that you don’t need to take the medication if you are not that sick.  I am seeing more people who are fully vaccinated, and not that sick, so the medication will not help in that situation. 

If you do test positive, you would schedule a video or phone visit

I would also make sure you have a pulse ox machine so you can assess your oxygen levels.” 

So I see three red flags here:

1) Is it necessary to get that creatinine blood test done prior to taking paxlovid? 

2) And, “if you are not that sick”…”the medication will not help in that situation”. Isn’t the reason to take paxlovid to prevent me from progressing to a more serious illness?

3) And with his seeming hesitancy to prescribe it early on, what is the point of telling me that I need a pulse ox machine to let me know later that second week that I now have more serious disease when in all likelihood it could have been prevented if I had taken paxlovid that first week?!

Based on your many recommendations, I think maybe it is time for me to find a new primary care provider?

I very much value your input. 

Thank you,