AB.4 and BA.5 Variants, Pandemic Fatigue, and Waning Immunity: A Toxic Mix 


Few individuals in the United States are currently wearing masks, and many are continuing to engage in risky behavior. This may well be a toxic mix, and healthcare facilities and infection preventionists need to prepare for another possible surge in cases.   

Kevin Kavanaugh, MD

Kevin Kavanaugh, MD

In the beginning of the Omicron surge, the COVID-19 deniers were stating that no one died of the Omicron. At the end of the wave, the United States had more deaths than with Delta.

On Dec. 14, 2021, Infection Control Today® warned in an article entitled “Omicron’s Mild Symptoms Can’t Mask Danger It Poses” that “those who are not vaccinated or immunosuppressed are at risk for severe disease.” On Dec. 20, 2021, Reuters reported that “infections caused by the Omicron variant of the coronavirus do not appear to be less severe than infections from Delta, according to early data from the UK.” Despite the early warnings, reporting on infections being more benign with a lower-case fatality rate continued in most of the news media. This month, a definitive study from Harvard and the Massachusetts General Hospital concluded that the “Omicron variant is as deadly as previous waves after adjusting for vaccinations, demographics, and comorbidities.”

The confusion occurred because Omicron’s case-fatality rates are biased with the inclusion of a large number of vaccinated individuals. If someone concluded that the disease from Omicron was less severe, and thus, they do not need to become vaccinated and protect themselves, then they might have made a fatal error and, at the very least, increased their risk of developing long COVID-19.

For those who have not recently recovered from an infection or let their vaccination immunity wane, their chances of dying or getting long COVID-19 by undertaking a risky activity is far too high. One must remember that even with a low case fatality rate, very high infectivity can overcome the lower virulence by producing a large number of severe cases. Thus, their chances of getting sick during an event is a combination of the infectivity and virulence of the virus; and infectivity increases the chance of severe illness exponentially.
Unfortunately, one’s protection from an infection is not durable. The virus mutates and immune escape variants emerge. This appears to have happened in South Africa with the BA.4 and BA.5 variants. An estimated 90% of the population of South Africa has been exposed to Omicron, and they are still undergoing another surge with the new variants (See Figure).

BA.4 and BA.5 are thought to be 36% more infectious than the BA.2 Variant and effectively evade immunity. The severity of the disease is not known. Initial reports from South Africa indicate that severity is similar to Omicron; however, the accuracy of reporting from South Africa, similar to Sweden, has come under fire. An article in The Lancet reported South Africa’s excess death rate to be 3.31 times higher than their COVID-19 death rate—one of the highest ratios in the world.

The immediate outlook for the United States warrants concern. Cases are up 25% in the last week with hospitalizations increasing 9%. This increase is fueled by the BA.2 variant and its more infectious offspring, BA.2.12.1. The BA.2.12.1 variant is more infectious than BA.2 and currently comprises 36% of sequenced cases in the United States (as of April 30).
The CDC has also reported the BA.4 and BA.5 variant in 14 states and is likely already in every state in the nation. Although only a few cases have been reported and these variants comprise only a small minority of sequenced cases, individuals need to react now. especially because the United States does not have the best active surveillance system for variants with “some European countries and even South Africa have better sequencing capabilities than the U.S.” Because of these risks, the CDC has restated their recommendation to wear masks on public transportation, and individuals may need to reevaluate the wisdom of holding large events such as the White House Correspondence Dinner. The latter may well be another super spreader event with staff from at least 5 news agencies testing positive for the virus.
Although many individuals measure success by the number who die of COVID-19, the ravages of long COVID-19 are deeply disturbing. The United Kingdom’s Office for National Statistics estimates that 10% to 25% of COVID-19 survivors may develop persistent symptoms. A recent study from the University of Cambridge found that “78% (of patients with long COVID-19) reported difficulty concentrating, 69% reported brain fog, 68% reported forgetfulness, and 60% reported problems finding the right word in speech.” Further, COVID-19 causes impairment similar to what occurs between the ages of 50 to 70, equivalent to losing 10 IQ points.
From Dec. 2021 to Feb. 2022, the seroprevalence in the United States from SARS-CoV-2 infections was 58%. Since that time, many more infections from Omicron have occurred. In addition, 66% of the United States citizens are currently “fully vaccinated.” Thus, almost everyone in the United States has had some exposure to SARS-CoV-2. If herd immunity can be achieved, then the United States should have achieved it. If another surge occurs, unfortunately, those numbers may be the status quo.

With new variants emerging, cases rising and a more complete understanding of the dangers of long COVID-19, one can make a strong case for resuming public health measures intended to control spread and infections from this disease. Unfortunately, even in the face of waning immunity, few individuals in the United States are currently wearing masks, and many are continuing to engage in risky behavior. This may well be a toxic mix, and healthcare facilities, and infection preventionists need to prepare for another possible surge in cases.

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