9 September 2022 Blog Post: New Booster Shot "Heralds" COVID Seasonality

The latest bivalent boosters began shipping over the Labor Day weekend and have now become available in local pharmacies. These are termed ‘bivalent’ as they contain two messenger RNA (mRNA) components of the SARS-CoV-2 virus – one from the original (ancestral) strain and the other a common sequence between the BA.4 and BA.5 sublineages of the Omicron variant. The artist formerly known as ‘the booster’ (which was monovalent) containing only the original strain has been taken off the market entirely and is no longer available. In this way, there will be no confusion about which booster to give to a patient, as only one has approval currently.

The timing of the bivalent booster shipping coincides closely and not coincidentally with seasonal influenza shots. We received our annual flu shots in the office about two weeks ago and have been dispensing them to patients already. It is a not so subtle nod to the seasonality of COVID-19. White House COVID-19 Response Coordinator Dr. Ashish Jha suggested that the bivalent booster could be bundled with seasonal flu shots saying (somewhat cumbersomely) “I really believe this is why God gave us two arms – one for the flu shot and the other for the COVID shot.”

Despite Dr. Jha’s clear misconception about the intelligent design of two arms (which were an obvious evolutionary pressure to allow for the  crossover dribble) – his framing is similar to the advice I have been giving patients about the timing of the bivalent booster. The overall goal being established protection by the Thanksgiving holidays, which is when seasonal respiratory viruses begin to spread in earnest – fueled by travel, family gathering and increased time indoors. Typically I recommend that flu shots be delivered by the end of October although we continue to vaccinate patients well into January (particularly if we have a later season surge).

There is clear evidence of a seasonal distribution of COVID-19. Below is a graph of prevalence (percentage rate of cases per 100 population) by week for Los Angeles County. There are three lines: 2020 (Blue), 2021 (Red), 2022 (Yellow)

Looking at the graph it is clear that there are low seasons: March to June (all years although remember in 2020 we were ‘flattening the curve’ and in 2021 we still had Spring mask mandates) and September to November (which is interesting because there is a lot of fretting that goes on with the opening of school in the Fall).

Summer 2022 showed a clear rise in cases but the obvious seasonality begins mid to late November (2020 especially), peaking mid January (Omicron in yellow was indeed everywhere in 2022) before falling rather rapidly by early February.

So the rollout of the updated COVID-19 boosters targeting the BA.4 and BA.5 subvariants are indeed meant to head off a 2022/2023 winter surge but also give us a sense of how the CDC is shifting our pandemic approach to a more predictive rather than reactive response. 

Dr. Fauci echoed this sentiment in classic Fauci speak: “It is becoming increasingly clear that—looking forward with the COVID-19 pandemic, in the absence of a dramatically different variant—we likely are moving towards a path with a vaccination cadence similar to that of the annual influenza vaccine, with annual, updated COVID-19 shots matched to the currently circulating strains for most of the population.”

𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿

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