The delta variant is already the most dominant strain of the virus in some U.S. states, and that’s putting some Americans easing back into “normal” life on edge.
This variant, which was first identified in India in December, now makes up nearly half of COVID-19 cases in some regions and one-quarter of cases in the U.S., based on virus samples that have been sequenced, according to remarks made Thursday by Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.
Delta’s takeover in the U.S. is inevitable, but it’s still unknown how the more transmissible strain will impact a country with vaccination rates that fluctuate wildly depending on the region.
About 47% of people in the U.S. are fully vaccinated, but at least 1,000 counties, primarily in southeastern and midwestern U.S. states, have vaccination rates below 30%.
“In some of these areas we are already seeing increasing rates of disease,” Walensky said.
Do all vaccines provide protection against the delta variant?
The emergence of the delta variant has raised questions for some of the 12 million or so Americans who got the Johnson & Johnson JNJ, +1.82% shot. A few people are asking if they should get a mRNA shot as a kind of off-label booster against the virus.
“That is being decided on an individual clinician level with their patient,” said Dr. Edward Stenehjem, an infectious-disease doctor at Intermountain Healthcare hospital system in Utah. “That’s not something that I’m very comfortable with — the fact that we’ve seen zero data in terms of the benefits or the risks of mixing and matching vaccines.”
Until Thursday night, there were no direct clinical-trial data looking at how J&J’s vaccine performs against the delta variant. But then the company announced that blood samples from eight people participating in the Phase 3 clinical trial demonstrated that the shot provided neutralizing antibody activity against delta. The full data set has not yet been published.
“ ‘If it were me, and I had gotten the J&J, and I lived in California, as I do, I would not get another shot. I’m going to figure that I’m partly protected against it and fairly well protected against getting super sick and dying. I’m also going to reflect on the fact that I’m living in a state with a high vaccination rate.’ ”
Prior to that announcement, the only data supporting J&J’s shot were inferred, based on what we know about AstraZeneca’s AZN, +0.80% AZN, -1.15% vaccine, which is not authorized in the U.S. but uses similar technology to the J&J shot.
That vaccine has an effectiveness rate of 92% against hospitalizations caused by delta infections, according to a preprint published in June that analyzed real-world data from the U.K.’s public health department.
“Since these vaccines — the AZ and the J&J — are based on very similar platforms, one could anticipate and make a reasonable assumption that the results against the delta variant would be at least similar, perhaps even better,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and President Joe Biden’s chief medical adviser, told reporters on Thursday.
The same research out of the U.K. found that Pfizer Inc.’s PFE, +0.43% vaccine, developed with German biotech company BioNTech 22UA, -0.80% BNTX, , is 96% effective against hospitalizations caused by the variant. Moderna Inc. MRNA, -0.34% this week said its shot provides neutralizing antibody titers against delta, based on a study examining the sera from eight people in the Phase 1 clinical trial.
The case for or against vaccine mixing and matching
Several physicians told MarketWatch this week that they are hearing chatter about whether to recommend so-called booster shots to some patients.
This is an idea that has already gained traction in other countries. Canada said on June 1 that people there who got a first dose of AstraZeneca’s vaccine could get an mRNA vaccine for their second dose. This decision was based on concerns about rare blood clots associated with the AstraZeneca shot, as well as the desired immune response.
So-called mix-and-match data out of the U.K. have suggested that mixing vaccines can increase some of the side effects, though it is generally considered safe. The U.S. launched its first federal mix-and-match clinical trial for COVID-19 vaccines a month ago.
One caveat to consider for all mix-and-match studies is that much of the research so far is based on a small number of participants. The J&J and Moderna research examined sera in eight patients, while the U.K. study has about 800 participants.
“Whether or not we can definitively say is always going to be caveated by the fact that a lot of these studies, just given the pressure under which they’re being conducted, are pretty small,” said Dr. Amit Phull, an emergency-room physician and vice president of strategy and insights at Doximity Inc. DOCS, -5.53%, a social platform for physicians.
Still, getting another shot is allowed, legally, even with the Food and Drug Administration and other federal health officials not expected to issue recommendations, especially without strong clinical data.
“We still need to remember that in fact the J&J vaccine is a highly effective vaccine,” Fauci said. “There’s no real fundamental scientific reason to do that right now. When those data become available, you will see recommendations change according to the data.”
“If it were me, and I had gotten the J&J, and I lived in California, as I do, I would not get another shot,” said Dr. Bob Wachter, chairman of the department of medicine at the University of California, San Francisco. “I’m going to figure that I’m partly protected against it and fairly well-protected against getting supersick and dying. I’m also going to reflect on the fact that I’m living in a state with a high vaccination rate.”
As of Friday, California’s full vaccination rate sits at nearly 60%. In San Francisco, it’s higher, at 67%.
The delta variant is responsible for renewed mitigation measures
Even in California, there is growing concern about the variant. Los Angeles County on Monday began urging people to wear masks in shared indoor places even if they are vaccinated, and Illinois Gov. J.B. Pritzker this week told people in the state to carry a mask with them when they leave home.
“I would encourage everybody whether you’re vaccinated or not to bring your mask with you,” Pritzker said Monday.
That said, the idea that mitigation measures like wearing masks in shared indoor spaces or social-distancing standards could come back is likely to meet opposition in some parts of the country due to the politicization of the pandemic.
“If we start seeing a very large uptick in cases, and particularly if there’s a large uptick in hospitalizations, you’ll see the red-blue divide play itself out, and you’ll see states like California and New York go back to some more vigorous requirements,” Wachter said. “But, even there, I think they’re going to be hesitant to do that.”
Elsewhere, the World Health Organization this week also told people to continue masking, with Dr. Mike Ryan, executive director of the WHO’s Health Emergencies Programme, summing up the delta variant as the “most able and fastest and fittest of those viruses” on June 21.
The rise of the delta variant is behind new lockdown measures in Israel, Portugal, Australia, Malaysia and the U.K.
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