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By the time June 15 arrived and San Francisco and the rest of California emerged from the extended pandemic shutdown, Peter Johnston was fully vaccinated and ready to have one of the best summers of his life.
He frequented the bars and clubs in the Castro every Friday and Saturday, and a few weekday evenings in between. He rents a house in Carmel with friends, then goes up to Guerneville with another group. “It was definitely a Roaring Twenties sort of thing,” said Johnston, 29, who said he found himself linked to the celebrations following the end of the 1918-19 pandemic and World War I.
But the party ended abruptly two weeks ago, when Johnston woke up on a Monday feeling sick. He developed a bad cough, followed by fever, chills and body aches. He tested positive for the coronavirus a week later.
“I would definitely say I thought the pandemic was over, or at least firmly in the rearview mirror,” Johnston said from his home in Castro, where he is still recovering. “I knew there was a possibility of contracting COVID after being vaccinated, but I didn’t think that would happen to me.”
There is mounting evidence that post-vaccination breakthrough cases like Johnston’s are not as rare as previously thought, or perhaps hoped for. And the culprit appears to be the highly contagious Delta variant that now dominates San Francisco and pretty much everywhere else in the United States.
Let’s be clear: vaccines hold up when it comes to preventing the most serious consequences, especially hospitalization, intensive care requiring ventilation, and death. They are also still very good at preventing infection. Vaccines remain the best protection against COVID-19 and are essential to ending the pandemic.
Peter Johnston, who lives in the Castro district of San Francisco, was infected with the delta variant after being fully vaccinated against COVID-19. “I knew there was a possibility of contracting COVID after being vaccinated, but I didn’t think that would happen to me.”
Nick Otto / The Chronicle SpecialBut delta is proving to be the first variant to test the strength of vaccines, especially when it comes to stopping transmission. And that, in turn, has resulted in disheartening setbacks in the public health response as cases rise faster now than at any time during the pandemic and health officials consider new warrants to mask and d ‘other measures to stop the spread of the disease.
“It’s COVID on steroids. In many ways, this is a different virus than the one we faced earlier this year, ”said Dr. Grant Colfax, director of the San Francisco Department of Public Health, during a briefing. press Friday during which he implored people who are not. vaccinated to receive the vaccines now.
Vaccine and immunology experts say breakthrough infections, while disappointing, are not unexpected and do not mean COVID vaccines are failing. Indeed, post-vaccination case studies and better data on why they can occur, underscore that the vaccine-induced immune response is robust and multi-layered.
Growing evidence suggests that delta is so easily transmitted largely because it replicates much faster than previous variants and exposes people to a much higher viral load.
This larger viral dose can crush the antibody response the first time in people who have been vaccinated, who were better able to get rid of previous variants and remain symptom-free. It can also mean that they are infectious and able to transmit the virus to others, perhaps as easily as those who are not vaccinated – a particularly disheartening finding, health experts have said.
But antibodies aren’t the immune system’s only tool to fend off the coronavirus. And so far, it seems the top-level response – namely T cells and B cells that clear the virus capable of escaping antibodies – is doing its job well and preventing serious illness.
“The vaccines maintained complete protection against serious and critical illness, even with the delta,” said Dr Catherine Blish, an infectious disease expert at Stanford. “Most of these (post-vaccination) cases that we see are mild or sometimes moderate illnesses, and that means the vaccine gives people a head start to clear the virus, but it’s not quite. enough to prevent infection in the first place. But at least it keeps them from going to the hospital.
When the vaccines were initially rolled out, although health experts noted that revolutionary infections would occur, it was understood that they would be rare and, in most cases, would cause asymptomatic or very mild illness. And that seemed to hold up for a while, as vaccination rates skyrocketed in the spring and cases plummeted. At the time, two variants dominated California, both more infectious than the original viral strain – but each, it is now believed, half as infectious as delta.
In the delta phase of the pandemic, breakthrough infections remain rare, but they are hardly uncommon. The UCSF has reported 140 cases of coronavirus among its 35,000 employees since mid-June – and 80% of those infections were in people who were fully vaccinated. Similar scenarios have occurred across the country, including at a homeless shelter in Santa Rosa.
Friday’s report from the Centers for Disease Control and Prevention focused on 469 cases associated with rallies in one county in Massachusetts; About three-quarters of the cases were in fully vaccinated people, and 79% of these had symptomatic illness. Of particular concern to health experts: The viral load was about the same between those who were vaccinated and those who were not, suggesting that they may also pass the virus on to others.
This report, along with other evidence around the world, prompted the CDC to recommend that even people who have been vaccinated resume wearing masks.
“This does not bode well for the concept of collective immunity to the delta,” Nadia Roan, a researcher at the Gladstone Institutes in San Francisco, said of the CDC report. She said it is possible that those vaccinated could carry a “dead” virus that is not able to infect others – which would not necessarily be apparent in the type of testing performed by the CDC. “Nonetheless, these data are worrying,” she said.
Scientists are still trying to determine how much more infectious the Delta is and why. Dr Charles Chiu, who heads UCSF-Abbott Viral Diagnostics and Discovery Center, said the delta had several mutations that were already associated with increased infectivity and resistance to vaccines, including the L452R mutation found in the variant. said Californian discovered by Chiu in January.
“It’s like a super L452R because of the way it’s developed,” Chiu said. “It’s probably the combination of these mutations that gives all of these benefits to delta.”
Its main benefits appear to be a rapid replication cycle – how quickly it can take hold of cells and establish infection – and the high viral load it delivers on exposure. People are contagious over a longer period of time with delta than with other variants, and they have many more viruses in their nose and the rest of their upper respiratory tract.
A preprint article published last week by scientists at Helix – a San Carlos genomic sequencing company that has performed coronavirus testing across the United States – found evidence that the viral load with delta may be three times higher than with alpha. Another study in China found a thousand-fold increase in viral load with delta compared to the original strain of the coronavirus.
“The threefold difference in our data is probably big enough that even if you are fully vaccinated, if you are infected you may not get seriously ill, but you could still pass it to someone. other, “said William Lee, vice president. for science at Helix.
COVID vaccines induce a significant antibody response – in fact, far more than what is needed to fend off infection with the original coronavirus strain and most variants. But the antibodies decrease, often a few months after vaccination. Studies in Israel have shown a drop in vaccine effectiveness within six to ten months, although some experts question the data.
The delta variant is probably able to overcome the antibody response to some extent. This is why even people who have been vaccinated can become infected and have mild to moderate illness. But vaccines also induce a cellular response, which takes longer to rally than antibodies but is more potent. This response is probably what keeps the infection from spreading beyond the upper respiratory tract and into the lungs of people who have been vaccinated.
“The vaccine, while it cannot prevent all cells from being infected, it can prevent the virus from deepening and causing disease,” Blish said.
Johnston, who has been battling symptoms of COVID for almost two weeks, said it was the worst he had felt since having a pneumonia attack at the age of 13. , I would be in the hospital right now, ”he said.
“Overall, I am a very healthy person. I didn’t really expect to have a hard time with COVID if I got it, ”Johnston said. Two fully vaccinated friends who he was with the night he believed he was infected also tested positive, but their symptoms were much milder, he said.
Johnston was so eager to get the shot that he drove four hours to Tulare County for his first injection in April, at a time when demand still far exceeded supply. Falling ill, even with a rather embarrassing illness, made him more pro-vaccination.
“I had some frustration, some anger, especially with the low vaccine uptake,” he said. “Vaccination is for the public good. Most of the benefits accrue to others, not to yourself. But I guess in order to get people vaccinated you basically have to mandate him. “
San Francisco Chronicle editors Catherine Ho and Danielle Echeverria contributed to this report.
Erin Allday is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @erinallday
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