13 September 2022 Blog Post: Fall 2022 COVID Boosters

What is in the new boosters? Is there any difference between the Pfizer and Moderna formulations?

Both new vaccines consist of equal portions of mRNA directed against the ancestral 2020 strain of the virus and mRNA directed against the newer Omicron BA.4 and BA.5 variants. The BA.5 is the primary variant that is circulating currently at 87.5% of samples studied.  BA.4 is far less frequently seen at 2.2% (link: https://covid.cdc.gov/covid-data-tracker/#variant-proportions). The Pfizer product may be used by adolescents (age, ≥12) and adults; the Moderna product may be used only by adults (age, ≥18).

Are there any studies in humans to support the use of this BA.4/BA.5 bivalent booster?

No – there are no clinical studies as yet supporting its use.  Animal and limited human studies have confirmed excellent antibody production against both ancestral virus and variant strains but there is no information regarding its efficacy. Canada, the UK, and the European Union have approved earlier bivalent boosters that target Omicron variant BA.1. Neither the Pfizer nor the Moderna BA.4/BA.5 bivalent booster that was authorized by the U.S. FDA is in use elsewhere in the world.

What happened to the old booster? Do I need to ask specifically for the new booster so I don’t get the old one?

The original Pfizer and Moderna monovalent mRNA COVID-19 vaccines are no longer authorized for use as boosters in the U.S. for adolescents (age, ≥12) and adults. Only children (age, ≤11 years) who received a primary vaccination with a monovalent product can receive a dose of the Pfizer monovalent vaccine as a booster. For everyone else, the new bivalent vaccines are the only boosting options so there is no need to ask for a specific booster.

How long should I wait from my last booster or primary series before getting this new one?

Both new vaccines are intended for use at least 2 months after a previous vaccination (whether a primary series or a first or second booster). As with prior boosters, the general recommendation for those that have had a recent community acquired infection is to wait at least 3 months before boosting after infection.

If I decide to take the new booster, when should I receive it?

This is an individual choice and has a number of factors to consider but waiting is a reasonable choice at this juncture. Firstly, for those concerned about the lack of human safety and efficacy data, it may feel more comfortable to simply wait until those data become available. Secondly, prevalence rates here in Los Angeles have been decreasing steadily since a mid-July peak making coming into contact less likely at the population level (Figure 1 below) so delaying vaccination makes sense from that standpoint as well.

Patients planning to attend a high-risk event or who are traveling in the fall might decide to get a booster a few weeks beforehand (generally two weeks before departure is about the latest one should wait). Others might prefer to wait until early winter in anticipation of the cold-weather surge in respiratory infections including COVID (we covered COVID seasonality in a post earlier this month). This latter approach fits too with the CDC’s seasonal guidance wherein they are recommending COVID booster and flu shots together (link: https://emergency.cdc.gov/coca/calls/2022/callinfo_090822.asp). 

𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿

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