When the Omicron subvariant of the Covid-19 virus came on the scene, it didn’t follow the pattern that scientists came to expect. In earlier surges, two or three weeks after cases spike, hospitalizations and deaths rose as well. With Omicron, both increased, but more slowly, and topped out at lower levels.
The difference between Omicron and previous versions of Covid-19 led to the widely held belief that Omicron isn’t as bad. However, Dr. Christopher Chiu, a COVID-19 researcher at Imperial College London, points out, “There is no real evidence for that.” The data shows that over 200,000 of the country’s more than 1,030,000 Covid-19 deaths are attributed to the Omicron variant, and it’s still killing over 400 people a day.
Why is there a difference between Omicron and other Covid-19 variants?
One key element is that there are now treatments available that weren’t when the initial strain or the Alpha and Delta variants were raging. However, the primary factor is immunity. According to Dr. Chiu, “Omicron is largely causing breakthrough infections in people who already have partial protection from immunity conferred by vaccines or infection.” By the time the Omicron subvariant arrived, nearly 60% of Americans had the protection of Covid-19 vaccines, and roughly 30% of Americans (including some who’d been vaccinated) had already been infected with the coronavirus.
In June, the Centers for Disease Control and Prevention (CDC) determined that Covid-associated hospitalizations were 4.6 times higher for unvaccinated adults than vaccinated people. Yet, it’s essential to point out that vaccinated people have varying degrees of immunity and recovery time from infections. Factors influencing the readiness of a person’s immune system are how long ago they had any previous infections, what variant infected them, their current vaccination statuses, and other factors such as their ages and the medications they take.
Given that Omicron’s severity is impacted by vaccination status, many individuals wonder if they should get another vaccine booster. If so, when?
An increasing number of studies show that when the Omicron variant infects, it triggers the immune system just like any other illness to rapidly activate immune memory cells that are already on standby, created by previous vaccinations or infections.
According to Rosemary Boyton, a professor of immunology and respiratory medicine at Imperial College London, “People are now walking around with different immune-imprinted covid responses, depending on what vaccine schedules they’ve had — one, two or three doses — and what infections they have had in the past. Imprinting is different according to where you live in the world, what vaccines you received — and that’s determining the subsequent immune response.”
Using the flu as an example, when an individual encounters a flu strain similar to the one they were first exposed to, they’re better protected against severe illness. The 1918 flu pandemic was caused by an H1N1 strain, which circulated for decades afterward. During the 2009 H1N1 pandemic, older people exposed to H1N1 in childhood had stronger immune responses than younger people infected with other strains.
Since Covid-19 and all its variants are so new, how closely it’ll follow the process is unknown. Despite the uncertainty, many scientists feel moving forward with boosters targeting specific variants and subvariants is a good idea because even though the protection is short-term, they’ll most likely prevent severe illness.
As far as the timing of the booster, experts say it depends. The CDC recommends that everyone receive booster shots as soon as they’re eligible. Currently, all adults who are 50 or older and anyone 12 and older who are immunocompromised can receive a fourth shot.
So, if you’re under 50, don’t have underlying health conditions, and have already received one booster shot, you can wait for the Omicron-specific booster shot. Also, experts indicate that people with “hybrid immunity,” who received a booster shot in the past and recovered from a Covid infection, should wait for the Omicron-specific shot.
The targeted vaccines are set to be released shortly after Labor Day.