There does not seem to be any specific recommendation on getting the same or different brand of COVID-19 vaccine. (However, if you only got Janssen before, it is no longer available in the US, and does not appear to have new variant formulations.)
- In favor of the same brand: minimize the (very small) risk of adverse effects if you got that brand of vaccine before without adverse effects (versus a different brand with different ingredients, etc.).
- In favor of a different brand: different brands of vaccines may stimulate the immune system differently, possibly leading to a more robust immune response.
- In favor of a specific brand:
- Pfizer: some younger men may want a lower dose (versus Moderna) to minimize the (very small) risk of myocarditis*.
- Moderna: some older people may want a higher dose (versus Pfizer).
- Novavax: some people may want a “more traditional” protein subunit + adjuvant vaccine over an mRNA vaccine. Some people may see hints that Novavax immune response may be more durable over time than for mRNA vaccines.
*Myocarditis rates were very low with the 2022 boosters – possibly because (a) the Moderna booster has a lower dose than the Moderna original that had the highest rate of myocarditis in its second primary dose, (b) the time interval before booster doses was longer than between the primary doses where myocarditis was observed, and (c) those who had vaccine-associated myocarditis were less likely to get boosters.