[Larry Corey] What we know about delta and vaccination

Sobering findings of the past few weeks have shaken both the American and scientific psyche. People have had to reassess their perceptions about the COVID-19 vaccines, and the reemergence of an epidemic many thought was over. Many of us have had to come to terms with how life can sometimes just be complicated.

It’s been a scientific and emotional roller coaster. In the spring, we saw the alpha variant, which was two times more infectious than the ancestral strain. That was followed by beta, which was eight times more resistant to laboratory assays and to neutralization with therapeutic antibodies in the petri dish. That variant was worrisome, because it was more capable at resisting vaccines. We were lucky because it was outcompeted by alpha -- a variant that the vaccines could handle.

Now delta is here and just ripping through both of them, like a hot knife through butter. It’s replacing beta with the same rapidity that it replaced alpha and all the in-between variants. It’s now the dominant variant in the US, showing up in more than 90 percent of positive cases.

So, what is it about this delta, or what I should say, many deltas?

What we’re seeing is this scientifically fascinating, but epidemiologically disconcerting change in the virus that’s happened at an incredibly rapid pace. Delta has some new characteristics which make it a formidable foe. It’s much more infectious to others; initial viral loads in the nose seem to be somewhat higher than previous strains with more rapid spread into the lungs and other organs within the body.

It is clear that the amount of virus required to infect others is lower, making transmissibility to household and casual contacts more efficient than the other variants. The average person who contracts a delta infection transmits the virus to between five and nine other people -- making this variant far more infectious than the original ancestral strain from a year ago.

Case numbers, predictably, are quickly increasing. Younger adults are being hospitalized. ICUs are filling up. Most disconcertingly, we are seeing more children being admitted in our pediatric hospitals. When we look at who’s in the hospital among adults, we see about 95 to 98 percent are unvaccinated. The same pattern is seen with children. The COVID-19 delta strain is a hospital epidemic of the unvaccinated.

With more than 100,000 cases a day being tallied in the US, it’s clear we need to take some new countermeasures to slow the spread.

Let’s look at vaccination and delta as it relates to the US:

The mRNA and Janssen vaccines both are highly effective against death and hospitalization (greater than 90 to 98 percent).

The protection from getting symptomatic COVID-19 appears to be a bit less with the delta variant -- studies show a range from 85 percent to 40 percent -- and this may differ by time post vaccination. But in all studies the severity of illness is markedly less -- the immune system of vaccinated persons can rapidly clear delta. As noted above, severe disease among the vaccinated in the US with the mRNA or Janssen vaccines is rare.

Transmission to others from vaccinated persons can occur, but it is less than from the unvaccinated population, although we have not yet demonstrated how much less.

So, yes, one can still get infected with delta despite being vaccinated if one doesn’t use precautions. That’s a fact. But a bigger fact is that you won’t get very sick, and you can reduce the risk of acquiring COVID-19 and spreading it if you wear a mask.

Perhaps we shouldn’t have been surprised. We understood that reducing acquisition of COVID-19 was a harder goal than ameliorating disease. But we do know the vaccines work and countless lives have been saved by them. So, the vaccines have markedly changed the dynamic of our thought process, but maybe what we need is to change our expectations.

It is true that the delta variant has swept in like a cold, damp morning shrouded by fog. And it’s left us with a bit of a shiver. But like all days, morning turns to afternoon and the sun gets higher in the horizon and some of the fog lifts. Although delta has taken us two steps back, a much more important step forward is to continue to vaccinate as many of our citizens as we can -- here in the US and around the world.

Once we do, delta may move itself two steps back, putting us once again two steps forward toward pre-COVID-19 normalcy.


By Dr. Larry Corey

Dr. Larry Corey
The writer is the leader of the COVID-19 Prevention Network Operations Center, which was formed by the National Institute of Allergy and Infectious Diseases at the US National Institutes of Health to respond to the global pandemic, and the chair of the ACTIV COVID-19 Vaccine Clinical Trials Working Group. He is a professor of medicine and virology at University of Washington and a professor in the vaccine and infectious disease division and past president and director of Fred Hutchinson Cancer Research Center.
This is a shortened version of an article titled “Vaccination and the delta variant: Four steps foward and two steps back,” published earlier at timmermanreport.com.– Ed.

[Overview of Global Bio Conference 2021]
Date: Sept. 13-15, 2021 (Mon-Wed)
Venue: Grand InterContinental Seoul Parnas and online
Theme: A New Normal: A Leap towards Newly Found Future of Biopharmaceuticals

With a global paradigm shift in the health care industry, where people turn more toward preventive measures than treatments, living a “healthy” long life is far more important than living “longer.”

With this flow, biopharmaceuticals take center stage with their key potential in combining biology and advanced technologies to cope with a novel infectious disease and rare incurable disease. Now that we are on this shifting tide, it is imperative to take measures for biopharmaceuticals’ leap toward the newly found future. At the GBC 2021, world leaders in biopharmaceuticals gather to discuss “What is the current situation that biopharmaceuticals are facing NOW?” “What are we expecting NEXT?” and “What is the future and BEYOND?” In addition, there will be further discussions on the sustainable future and insights on advanced biopharmaceuticals toward the “New Normal” and even the “Next Normal.”



By Korea Herald (koreaherald@heraldcorp.com)