Delta: Variant pervasive, but hospitalizations and deaths are still very rare
As COVID19 cases climb across California, socalled breakthrough infections among people who are fully vaccinated also are increasing, raising concerns that the highly contagious delta variant — now the dominant strain — may be better able than other strains to evade vaccines.
Many infectious disease experts say, however, that the data so far does not support the notion that delta is breaking through more often. The vaccines, they say, are holding up as well as ever. And even if delta proves better able to infect vaccinated people, all evidence shows the
All evidence shows the vaccines remain powerfully effective at preventing serious illness and death.
vaccines remain powerfully effective at preventing serious illness and death.
Even as cases climb among the vaccinated and unvaccinated alike, those who have not gotten shots make up well over 95% of hospitalizations and deaths in California and the U.S. When fully vaccinated people end up hospitalized or dying of COVID19, they are almost always older — over age 80 — and have multiple underlying health problems, public health officials say.
Fully vaccinated people who test positive often are asymptomatic, their cases caught through routine screening, or they have mild illness not much worse than the common cold. It’s possible, some experts say, that the delta variant is leading to more of those cases. A small, notyetpeer reviewed study released this week suggested that the Johnson & Johnson vaccine in particular may be less effective against delta than the Pfizer and Moderna shots.
Anecdotal reports of such breakthroughs are increasing in frequency, though that’s at least partly because with most pandemic restrictions now dropped, people are interacting more and no longer taking precautions like wearing masks.
This week a senior staff member to House Speaker Nancy Pelosi tested positive, along with a White House official. Both were fully vaccinated, and their cases were asymptomatic or mild. Earlier this month, the California Capitol reinstated a mask mandate after nine legislative staff members tested positive, including four who were vaccinated.
“Some of what we’re seeing is that people get screened, and they have (the coronavirus) but they’re not really sick,” said Dr. Julie Parsonnet, a Stanford epidemiologist. “The vaccine is doing its job of preventing the virus from getting into your body and making you really sick. We should still feel confident about the vaccines.”
In California, the delta variant is thought to make up more than half of all cases now, and is reported at much higher levels in some counties. Nationally, the variant makes up more than 80% of new cases, according to the Centers for Disease Control and Prevention.
The variant is thought to be up to 100% more infectious than the original coronavirus strain, and it’s devastating some parts of the country where vaccination rates are around 30%, or lower. California is in a much stronger position, with higher vaccination rates than the national average. But cases are still climbing here, too — daily new cases have nearly tripled since the start of the month statewide.
Eight of nine Bay Area counties have recommended all people resume wearing face coverings in indoor public spaces due to climbing case rates, and Los Angeles issued a new mask mandate last week. The masks are meant mostly to protect the unvaccinated, who may have stopped wearing face coverings despite orders to keep them on.
But public health officials said that with the virus now circulating widely in many places, masks will protect fully vaccinated people too — either from the rare case of serious illness or death, or from transmitting the virus to others who may be vulnerable, like children not yet eligible for vaccination or people who are immune compromised.
As of Wednesday, 14,365 postvaccination cases had been identified in California. Of those, at least 843 were hospitalized and 88 died, though within those groups, some people may have tested positive but their deaths or illness were not due to COVID19. Bay Area counties report that unvaccinated people make up 80% to 100% of all COVID19 hospitalizations, and close to 100% of all deaths.
California does not publicly report daily case rates among vaccinated versus unvaccinated individuals, but some counties do. In the Bay Area, case rates are vastly higher among unvaccinated residents.
In Marin County, for example, the case rate is 2.5 per 100,000 vaccinated residents, while the rate among unvaccinated people is 12.2 cases per 100,000; in San Francisco, it’s 5.8 cases per 100,000 vaccinated residents and 15 cases per 100,000 unvaccinated. Those unvaccinated rates would have set both counties deep into the purple tier under the state’s retired pandemic blueprint.
“We’re seeing increased cases related to the delta variant. And one in four of our cases are fully vaccinated,” said Dr. Matt Willis, the Marin County health officer. “But we’ve had 177 total breakthrough cases, and of those, three have been hospitalized. And no one who was vaccinated has died.”
Similarly, San Francisco has not reported any deaths among vaccinated residents. “The vaccines are meant to prevent the severest consequences of COVID and they’re doing a great job with that,” said Dr. Naveena Bobba, San Francisco’s deputy director of health.
Scientists don’t fully understand why some people test positive despite being vaccinated. In many cases, it’s likely that the virus infects them superficially, in the nose or other part of the upper respiratory tract, in large enough amounts that it shows up on a sensitive test. They’re technically infected, and may be able to transmit the virus, but they’re not sick.
The delta variant may be better able to cause that kind of infection, scientists say, perhaps by hitting people with much higher viral doses than earlier variants, which may be enough to overwhelm the vaccines’ antibody response. But vaccines induce immunity with more than just antibodies; other immune functions like Tcells, which are less likely to be weakened by a variant, may prevent more serious illness.
Another important factor leading to increased cases among the vaccinated is simple math: More vaccinated people means more breakthrough cases. Ironically, in places like the Bay Area with overall high vaccination rates, it’s expected that vaccinated people would make up a higher proportion of cases than in places with low vaccination rates.
The key point is that they won’t get as sick. So even as cases climb dramatically — they’ve more than doubled in Bay Area counties since reopening of the economy — hospitalizations aren’t rising nearly as quickly, and deaths shouldn’t either.
“This is why we got vaccinated — so we can feel free to move around and go about our lives, and if you encounter the virus, you’re protected from serious disease,” said Dr. Jay Levy, a UCSF infectious disease expert. “If anything, getting exposed to the virus boosts the immune system.”
Still, the cases among vaccinated people can be disconcerting, especially among those who are breakthrough cases.
Victor Bolan of Oakland said he was frustrated to get sick months after being fully vaccinated. He’d been so cautious for a year and a half, wearing a mask any time he was around others, but he dropped his face covering one weekend after the state reopened and went to work at a bar, plus a couple of parties with friends and a wedding.
“The one weekend you can take your mask off, and you get sick,” Bolan said. “I got sick around the third week of June. I couldn’t go back to work until last week. That’s three weeks of missing work. I’m just going to stick with my mask at this point.”
Sarah Feldstein said she was similarly upset when she tested positive long after being fully vaccinated. But she was grateful, too, because her symptoms were mild and no one around her got sick. That leads her to believe the vaccine was working.
“At first I was kind of like, how did this happen? I can’t believe it,” said Feldstein, who lives in San Francisco. “Then you realize of course there are going to be breakthrough cases, it’s inevitable, and the symptoms are mild. The vaccine did what it was supposed to do.”