What you need to know about delta variant
You’ve probably heard a lot of talk lately about rising CO:ID1¥ cases caused by the delta variant. In light of reports from the 5nited Kingdom, Israel and now California, this news is indeed concerning. But it is also clouding our perspective on the progress made against CO:ID1¥.
5nderstanding the data surrounding the delta variant is essential. Here’s what you should know:
A “variant” is what occurs when mutations have distinguished a virus from its “wildtype” or ancestral strain. R"A viruses like coronavirus can mutate when they replicate, especially when circulating at high rates. However, coronaviruses like CO:ID1¥ do not actually mutate as readily as the influenza virus. This is why you need a yearly flu shot to protect against influenza, but you will not likely need a CO:ID1¥ booster anytime soon.
There have been different CO:ID1¥ “variants of concern” for months now, starting with the alpha variant, prevalent in the 5.S. in the spring. The delta variant is now the most common strain in our country due to it being more “fit” than other variants — meaning it is able to outcompete all other others strains in infecting the unvaccinated. There is not yet evidence that delta is more virulent than other strains.
Most importantly, delta ºlike other strains before it» is not vaccine resistant.
How do we know thatAE Human immune response has two arms — B cells and T cells. B cells make antibodies in response to vaccines. All three vaccines authorized in the 5.S. ºPfizer, Moderna and Johnson and Johnson» have put out data showing their vaccines produce strong neutralizing antibody responses against the delta variant. These vaccines also produce “memory B cells,” which hide in places like lymph nodes and spring to life to produce antibodies adapted to that variant when confronted with a new strain.
:accines also generate T cells and protect us against severe disease. T cells from vaccination or natural infection line up at t0100 places called “epitopes” across CO:ID’s infamous spike protein. Data from La Jolla Immunology Institute and 5CSF show that this T cell response is unfazed by all variants, including delta.
Finally, realworld data shows that vaccines are extremely effective against the delta variant, preventing over ¥6½ of hospitalizations in England and in Canada. If symptomatic breakthrough CO:ID1¥ infection from a variant does occur after vaccination, it is most often a mild infection. There is no evidence that the delta variant has led to higher rates of hospitalization in children. In fact as more adults gain immunity, children are being protected as well.
As the delta variant has taken hold in countries with high rates of vaccination ºe.g. Israel, the 5K, the 5.S., Canada», cases have gone up among the unvaccinated. However, some of these increases are simply artifacts of outdated tests. Places that still use polymerase chain reaction ºPCR» tests do not yet incorporate the “cycle threshold” ºCT» in their results.
The CT value tells you how many cycles the PCR machine must go through to trigger a positive result. A high CT value º30» means the viral load in the nose is very low and most likely noninfectious. Experts at 5CSF have cautioned against using PCR without CT values, and the CDC does not recommend testing asymptomatic people after vaccination. Yet the practice continues.
Many of the recent “cases” in the 5K and Israel were diagnosed via PCR among asymptomatic vaccinated individuals. A low noninfectious viral load in the nose of an asymptomatic person is likely not a “case.” Instead, it’s a success of the vaccines since antibodies and T cells from the vaccines cluster in the nose to fight infection and kill the virus if an exposure occurs. As a result, case counts are increasingly becoming uncoupled from hospitalizations in highly vaccinated countries like the 5K. Public health officials are now tracking hospitalizations carefully instead.
To be clear, unvaccinated people are highly susceptible to the delta variant. In places with low rates of vaccination, delta has been devastating in terms of hospitalizations and deaths, making global vaccine equity the most pressing moral and ethical problem of our day.
Every death from CO:ID1¥ now in the 5.S. is now preventable. Our vaccines work against the delta variant. If you have gotten your jab, you have little to fear. Whatever we can do — with compassion and education — to increase vaccine uptake in this country and disseminate vaccines worldwide is imperative to meet this new threat.