As highly-transmissible omicron subvariants circulate throughout the Midwest and U.S., a new coronavirus booster vaccine will look to loosen their hold.
Following recommendations set by an advisory panel from the U.S. Food and Drug Administration, the next generation of COVID-19 vaccines will be adjusted to better target the omicron COVID variant.
The booster shots could be distributed sometime in October or November, according to Chicago Department of Public Health Commissioner Dr. Allison Arwady.
"Once we know what that guidance looks like — the FDA and CDC are weighing in — we would have the timing for a potential fall booster campaign," Arwady said. "I'm guessing that fall booster campaign will come October, possibly November. It takes about three months to start producing, distributing, etc. doses that have that updated composition."
The Biden administration announced July 29 that it reached an agreement with Moderna to buy 66 million doses of the company's upgraded COVID-19 vaccine, which is enough of a supply for all of those who may want the booster in the winter.
The order of the bivalent shot follows the announcement last month that the federal government had secured 105 million doses of a similar vaccine from rival drugmaker Pfizer. Both orders are scheduled for delivery in the fall and winter, assuming regulators sign off on their effectiveness.
However, Arwady noted the difficulties of this possible development.
“This has been complicated because those subvariants continue to emerge. Neither company has developed the vaccine specific to BA.4, BA.5 because that just emerged in the last couple weeks," Arwady said last Tuesday. “There’s this question of when do you draw the line when it takes about three months for vaccines to be produced and distributed, but also wanting to make sure it’s the best match possible.”
Last Tuesday, Arwady said that the prevalent omicron strains, BA.4 and BA.5, are quickly shifting, with the latest two notably more infectious.
"The majority of the cases that we're seeing are either BA.4 or BA.5, and just as a reminder, BA.4, BA.5 are more contagious," Arwady said.
Aside from being even more contagious than previous variants, scientists are tracking a mutation in BA.4 and BA.5 that could help it evade some immunity and cause reinfections.
A genetic trait that harkens back to the pandemic's past, similar to what is known as the “delta mutation," appears to allow the subvariants "to escape pre-existing immunity from vaccination and prior infection, especially if you were infected in the omicron wave," said Dr. Wesley Long, a pathologist at Houston Methodist in Texas. That's because the original omicron strain that swept the world didn’t have the mutation.
This genetic change is bad news for people who caught the original omicron and thought that made them unlikely to get COVID again soon. Although most people don't know for sure which variant caused their illness, the original omicron caused a giant wave of cases late last year and early this year.
Long said lab data suggests a prior infection with the original omicron is not very protective against reinfection with the new mutants, though the true risk of being reinfected no matter the variant is unique to every person and situation.
With these two variants, Arwady noted that, in some cases, those previously infected with omicron "early on" have become reinfected with BA.4 and BA.5, including cases in Chicago.
"With BA.4, BA.5, we have started to see some examples, even of people who were infected with omicron early on, starting to occasionally get reinfected with BA.4 or 5," she said.
However, COVID vaccinations have continued to prevent severe hospitalization and death, Arwady said.
More than 23 million vaccine doses have been administered in Illinois since vaccinations began in December 2020. More than 69% of Illinois resident are fully vaccinated against COVID, with more than 76% receiving at least one dose. About 54% are also boosted.